JP2018172255A - Method for producing lithium-nickel composite oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a lithium-nickel composite oxide having high output at a high current rate with high voltage.SOLUTION: There is provided a method for producing a lithium-nickel composite oxide represented by the general formula (I), which comprises: a mixing step of mixing a lithium compound and a composite metal compound containing at least nickel to obtain a mixture; a calcination step of calcining the mixture to obtain a calcined product; and a post-treatment step including a washing step of washing the calcined product, in which a step comprises performing the mixing so that the molar ratio (Li/Me) between lithium contained in the lithium compound and metal elements in the composite metal compound containing at least nickel exceeds 1 and treating the mixture so that the total amount of the residual sulfuric acid radical and residual lithium carbonate in the lithium-nickel composite oxide obtained after the post-treatment step is 0.3 mass% or less and the content of sodium is 50 ppm or less.SELECTED DRAWING: None

Description

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

  Lithium nickel composite oxide is used as a positive electrode active material for lithium secondary batteries (hereinafter sometimes referred to as “positive electrode active material”). Lithium secondary batteries have already been put into practical use not only for small power sources for mobile phones and laptop computers, but also for medium and large power sources for automobiles and power storage.

  As a method for producing a lithium nickel composite oxide, a method comprising a production process of a lithium nickel composite oxide precursor, a mixing step of lithium and the precursor, a firing step, and a cleaning step after the firing step is known ( For example, Patent Documents 1 to 3).

International Publication No. 2013/015007 International Publication No. 2014/115380 International Publication No. 2014/189108

The cleaning step after the firing step is a step aimed at removing impurities. However, depending on the cleaning method, the output at a high current rate at a high voltage may decrease. For example, impurities are left in the case of insufficient cleaning, and lithium is eluted in the case of excessive cleaning, resulting in a problem that battery characteristics are deteriorated.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the manufacturing method of lithium nickel complex oxide with a high output in the high current rate in a high voltage.

That is, the present invention includes the following [1] to [9].
[1] A method for producing a lithium nickel composite oxide represented by the following general formula (I), comprising mixing a lithium compound and a composite metal compound containing at least nickel to obtain a mixture; And a post-treatment step including a firing step for firing and obtaining a fired product, and a cleaning step for washing the fired product, wherein the mixing step includes lithium contained in the lithium compound and a composite metal compound containing at least nickel The metal element in the mixture is mixed so that the molar ratio (Li / Me) exceeds 1, and the residual sulfate group and the residual lithium carbonate in the lithium nickel composite oxide obtained after the post-treatment step. Lithium nickel composite oxide characterized by including a step of treating so that the total amount is 0.3 mass% or less and the sodium content is 50 ppm or less Manufacturing method.
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(In formula (I), 0 <x ≦ 0.2, 0 <y ≦ 0.5, 0 <z ≦ 0.8, 0 ≦ w ≦ 0.1, y + z + w <1, M is Fe, Cu, Ti Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, and V represent one or more metals selected from the group consisting of V.)
[2] The method for producing a lithium nickel composite oxide according to [1], wherein y + z + w ≦ 0.3 in the general formula (I).
[3] The method for producing a lithium nickel composite oxide according to [1] or [2], wherein the firing temperature is 300 ° C. or higher and 1000 ° C. or lower in the firing step.
[4] The lithium nickel composite oxide according to any one of [1] to [3], including a drying step of drying the obtained lithium nickel composite oxide after the cleaning step in the post-treatment step. Production method.
[5] The lithium nickel composite oxidation according to any one of [1] to [3], including a refiring step of refiring the obtained lithium nickel composite oxide after the cleaning step in the post-treatment step. Manufacturing method.
[6] The method for producing a lithium nickel composite oxide according to [4], wherein the post-treatment step includes a refiring step of refiring the obtained lithium nickel composite oxide after the drying step.
[7] The post-treatment step includes a coating step of mixing the obtained lithium nickel composite oxide and the aluminum compound after the cleaning step and coating the surface of the lithium nickel composite oxide with the aluminum compound. [3] The method for producing a lithium nickel composite oxide according to any one of [3].
[8] The above post-treatment step includes a coating step in which, after the drying step, the obtained lithium nickel composite oxide and an aluminum compound are mixed and the surface of the lithium nickel composite oxide is coated with the aluminum compound. The manufacturing method of lithium nickel complex oxide of description.
[9] In the post-treatment step, the total amount of residual sulfate radical and residual lithium carbonate in the lithium nickel composite oxide obtained after the drying step is 0.6% by mass or less, and the content of sodium is 50 ppm or less. The method for producing a lithium nickel composite oxide according to [6] or [8], wherein the treatment is performed so that

  According to the present invention, it is possible to provide a method for producing a lithium nickel composite oxide having a high output at a high current rate at a high voltage.

It is a schematic block diagram which shows an example of a lithium ion secondary battery.

<Method for producing lithium nickel composite oxide>
The present invention is a method for producing a lithium nickel composite oxide represented by the following general formula (I). This embodiment includes a mixing step of mixing a lithium compound and a composite metal compound containing at least nickel to obtain a mixture, a firing step of firing the mixture to obtain a fired product, and a cleaning step of washing the fired product. A post-processing step.
In this embodiment, a mixing process mixes so that the molar ratio (Li / Me) of the lithium contained in a lithium compound and the metal element in the composite metal compound containing at least nickel may exceed 1.
According to the manufacturing method of the present embodiment, the total amount of residual sulfate radical and residual lithium carbonate in the lithium nickel composite oxide obtained after the post-treatment step is 0.3 mass% or less, and the content of sodium is 50 ppm. The process of processing to become the following is included.

_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(In formula (I), 0 <x ≦ 0.2, 0 <y ≦ 0.5, 0 <z ≦ 0.8, 0 ≦ w ≦ 0.1, y + z + w <1, M is Fe, Cu, Ti Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, and V represent one or more metals selected from the group consisting of V.)
Hereinafter, preferred embodiments of the method for producing a lithium nickel composite oxide of the present invention will be described.

<< First Embodiment >>
1st Embodiment is a manufacturing method of the lithium nickel composite oxide represented by general formula (I), Comprising: The mixing process which mixes a lithium compound and the composite metal compound containing at least nickel, and obtains this mixture, A firing process for firing the mixture to obtain a fired product, and a post-treatment process including a cleaning process for washing the fired product are provided in this order.
Hereinafter, each step will be described.

[Mixing process]
The mixing step is a step of obtaining a mixture by mixing a lithium compound and a composite metal compound containing at least nickel. In this step, first, a metal other than the lithium compound, that is, an essential metal composed of Ni, Co, and Mn, and Fe, Cu, Ti, Mg, Al, W, B, Mo, Nb, Zn, Sn, It is preferable to prepare a metal composite compound containing one or more arbitrary metals of Zr, Ga and V, and to fire the metal composite compound with an appropriate lithium salt. As a metal complex compound, a metal complex hydroxide or a metal complex oxide is preferable. Below, a mixing process is divided and demonstrated to the manufacturing process of a nickel containing complex metal compound, and the manufacturing process of a lithium metal complex oxide.

(Manufacturing process of nickel-containing composite metal compound)
The nickel-containing composite metal compound can be produced by a generally known batch coprecipitation method or continuous coprecipitation method. Hereinafter, the manufacturing method will be described in detail by taking a metal composite hydroxide containing nickel, cobalt, and manganese as an example.

First, a nickel salt solution, a cobalt salt solution, a manganese salt solution, and a complexing agent are reacted by a coprecipitation method, in particular, a continuous method described in JP-A-2002-201028, and Ni _x Co _y Mn _z (OH). ₂ A metal composite hydroxide represented by the formula (where x + y + z = 1) is produced.

Although it does not specifically limit as nickel salt which is the solute of the said nickel salt solution, For example, any one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate can be used. As the cobalt salt that is the solute of the cobalt salt solution, for example, any one of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate can be used. As the manganese salt that is the solute of the manganese salt solution, for example, any of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate can be used. The above metal salt is used in a proportion corresponding to the composition ratio of Ni _x Co _y Mn _z (OH) ₂ . Moreover, water is used as a solvent.

  The complexing agent can form a complex with nickel, cobalt, and manganese ions in an aqueous solution. For example, an ammonium ion supplier (ammonium hydroxide, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, etc.) ), Hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracil diacetic acid, and glycine.

  During the precipitation, an alkali metal hydroxide (for example, sodium hydroxide or potassium hydroxide) is added if necessary to adjust the pH value of the aqueous solution.

When the complexing agent is continuously supplied to the reaction vessel in addition to the nickel salt solution, the cobalt salt solution, and the manganese salt solution, nickel, cobalt, and manganese react to form Ni _x Co _y Mn _z (OH) _2. Is manufactured. During the reaction, the temperature of the reaction vessel is controlled within a range of, for example, 20 ° C. or more and 80 ° C. or less, preferably 30 to 70 ° C., and the pH value in the reaction vessel is, for example, pH 9 or more and pH 13 or less, preferably pH 11 or more and pH 13 or less. The substance in the reaction vessel is appropriately stirred while being controlled within the range. The reaction vessel is of a type that causes the formed reaction precipitate to overflow for separation.

  Since the reaction conditions depend on the size of the reaction tank used, the reaction conditions may be optimized while monitoring various physical properties of the finally obtained lithium nickel composite oxide.

  After the above reaction, the obtained reaction precipitate is washed with water and then dried to isolate nickel cobalt manganese hydroxide as a nickel cobalt manganese composite compound. Moreover, you may wash | clean with the alkaline solution containing weak acid water, sodium hydroxide, or potassium hydroxide as needed. In the above example, nickel cobalt manganese composite hydroxide is manufactured, but nickel cobalt manganese composite oxide may be prepared.

(Production process of lithium metal composite oxide)
The nickel-containing composite metal compound or nickel-containing composite metal hydroxide is dried and then mixed with a lithium salt. The drying conditions are not particularly limited. For example, the nickel-containing composite metal compound or the nickel-containing composite metal hydroxide is not oxidized or reduced (the oxide is maintained as an oxide, the hydroxide is a hydroxide). Maintained), conditions under which nickel-containing composite metal hydroxide is oxidized (hydroxide is oxidized to oxide), conditions under which nickel-containing composite metal compound is reduced (oxide is reduced to hydroxide) Any of the conditions). An inert gas such as nitrogen, helium and argon may be used for conditions where oxidation / reduction is not performed, and oxygen or air may be used for conditions where the nickel-containing composite metal hydroxide is oxidized. In addition, as a condition for reducing the nickel-containing composite metal compound, a reducing agent such as hydrazine or sodium sulfite may be used in an inert gas atmosphere. As the lithium salt, any one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, and lithium oxide, or a mixture of two or more can be used.
Classification may be appropriately performed after drying the nickel-containing composite metal compound or the nickel-containing composite metal hydroxide. The lithium compound and the nickel-containing composite metal compound are mixed so that the molar ratio (Li / Me) between lithium in the lithium compound and the metal element in the composite metal compound containing at least nickel exceeds 1. .

[Baking process]
By firing a mixture of a nickel-containing composite metal compound and a lithium salt, a lithium-nickel cobalt manganese composite oxide is obtained. For the firing, dry air, an oxygen atmosphere, an inert atmosphere, or the like is used according to a desired composition, and a plurality of heating steps are performed if necessary.

The firing temperature of the nickel-containing composite metal compound or the nickel-containing composite metal hydroxide and a lithium compound such as lithium hydroxide or lithium carbonate is not particularly limited, but from the viewpoint of preventing a reduction in charge capacity, 300 Preferably, the temperature is higher than 350 ° C, more preferably higher than 350 ° C, and even more preferably higher than 400 ° C. Moreover, although there is no restriction | limiting in particular, it is preferable that it is 1000 degrees C or less, and it is more preferable that it is 950 degrees C or less from a viewpoint which can prevent volatilization of Li and obtain the lithium nickel composite oxide of the target composition.
The volatilization of Li can be controlled by the firing temperature.
The upper limit value and the lower limit value of the firing temperature can be arbitrarily combined.

The firing time is preferably 1 hour or more and 30 hours or less for the total time from the start of raising the temperature to the end of temperature holding. When the total time is 30 hours or less, the volatilization of Li can be prevented and the battery performance can be prevented from deteriorating.
When the total time is 1 hour or more, the development of crystals proceeds well, and the battery performance can be improved.
In addition, it is also effective to perform temporary baking before the above baking. The temperature for such preliminary firing is preferably in the range of 300 to 850 ° C. for 1 to 10 hours. By performing the preliminary firing, the firing time may be shortened.

  By performing the firing step under the above conditions, volatilization of lithium can be suppressed. Thereby, a lithium nickel composite metal oxide having a high output at a high current rate at a high voltage can be obtained.

[Post-processing process]
The post-treatment step includes a washing step for washing the fired product obtained in the firing step, and the total of the residual sulfate radical and the residual lithium carbonate of the lithium nickel composite oxide obtained after the post-treatment step is 0.3% by mass or less, And it is the process of post-processing so that sodium may be 50 ppm or less.

[Washing process]
In the washing step, the washing liquid and the fired product are mixed to form a slurry, and the slurry is stirred to wash the fired product powder. At that time, the concentration (slurry concentration) of the slurry in which the cleaning liquid and the fired powder are mixed is not particularly limited, but is preferably adjusted to 50 g / L or more from the viewpoint of suppressing Li elution, to 100 g / L or more. It is more preferable to adjust. Moreover, from the viewpoint of providing sufficient handling properties, the concentration of the slurry (slurry concentration) in which the cleaning liquid and the fired powder are mixed is preferably adjusted to 2000 g / L or less, and more preferably adjusted to 1000 g / L or less. preferable.
When Li is eluted by the washing step, Li / Me of the lithium nickel composite oxide, that is, the molar ratio of lithium (the molar ratio of lithium to the total amount of metal elements excluding lithium) is lowered, but by adjusting the slurry concentration The decrease in Li / Me can be controlled.

Examples of the cleaning liquid used in the cleaning process include water and an alkaline solution. In the present embodiment, water is preferable.
Although the washing time is not particularly limited, it is preferably 1 minute or more, more preferably 5 minutes or more from the viewpoint of sufficiently removing impurities. Moreover, from a viewpoint of improving productivity, 60 minutes or less are preferable and 30 minutes or less are more preferable.

  By performing the washing step under the above conditions, impurities can be sufficiently removed and lithium can be prevented from being eluted into the slurry. Thereby, a lithium nickel composite metal oxide having a high output at a high current rate at a high voltage can be obtained.

In this embodiment, “impurities” are used to control sulfur-containing compounds (residual sulfate radicals) such as SO ₄ remaining on the surface of particles contained in the lithium nickel composite oxide after the firing step, residual lithium carbonate, and pH control. And the like in which alkali metal coprecipitation residues remain.
When sulfate is used as the transition metal, sulfate radicals resulting from this may remain. In the present embodiment, the source of the residual sulfate radical as an impurity is not particularly limited. For example, even when a sulfate is not used, a sulfur-containing compound remaining on the particle surface due to various materials used. Etc. are also included in the impurities.
Further, as the lithium carbonate as an impurity, when lithium carbonate is used as a lithium source, residual lithium carbonate resulting from this can be mentioned. Further, even when a lithium source other than lithium carbonate is used, lithium carbonate that can be generated by reacting with carbon dioxide in the air is also included in the “impurities”.

In the present embodiment, the post-treatment is preferably performed so that the total of the residual sulfate group and the residual lithium carbonate of the lithium nickel composite oxide obtained after the post-treatment step is 0.27% by mass or less, and 0.24% by mass. It is more preferable to carry out post-processing so that
Moreover, it is preferable to post-process sodium so that it may become 25 ppm or less, and it is more preferable to post-process so that it may become 15 ppm or less.

<< Second Embodiment >>
The present embodiment further includes a drying step after the cleaning step in the post-processing step of the first embodiment. That is, it has a mixing process, a baking process, and a post-processing process (cleaning process and drying process) in this order. The temperature and method for drying the lithium nickel composite oxide in the drying step are not particularly limited, but the drying temperature is preferably 30 ° C. or higher and more preferably 40 ° C. or higher from the viewpoint of sufficiently removing moisture. Preferably, it is 50 ° C. or higher. Further, from the viewpoint of preventing the formation of a heterogeneous phase on the surface, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower.

«Third embodiment»
The present embodiment further includes a re-baking step after the cleaning step in the post-processing step of the first embodiment. That is, it has a mixing process, a baking process, and a post-processing process (cleaning process and re-baking process) in this order. The description regarding the mixing step, the firing step, and the cleaning step in the present embodiment is the same as the description in the first embodiment.

[Refiring process]
The firing temperature in the re-firing step of the lithium nickel composite oxide is not particularly limited, but is preferably 300 ° C. or higher, more preferably 350 ° C. or higher, from the viewpoint of preventing a reduction in charge capacity. More preferably, it is 400 ° C. or higher. Moreover, although there is no restriction | limiting in particular, it is preferable that it is 1000 degrees C or less, and it is more preferable that it is 950 degrees C or less from a viewpoint which can prevent volatilization of Li and obtain the lithium nickel composite oxide of the target composition.
The volatilization of Li can be controlled by the firing temperature.
The upper limit value and the lower limit value of the firing temperature can be arbitrarily combined.

The re-baking time is preferably 1 hour or more and 30 hours or less for the total time from the start of raising the temperature to the end of temperature holding. When the total time is 30 hours or less, the volatilization of Li can be prevented and the battery performance can be prevented from deteriorating.
When the total time is 1 hour or more, the development of crystals proceeds well, and the battery performance can be improved.
In addition, it is also effective to perform temporary baking before the above baking. The temperature for such preliminary firing is preferably in the range of 300 to 850 ° C. for 1 to 10 hours.

  Moreover, impurities can be reduced by performing the re-baking step under the above conditions.

  In the post-treatment process having a washing process and a re-baking process, impurities can be sufficiently removed by performing the washing process and the re-baking process under the above-described conditions, and in the slurry in the washing process. Lithium can be prevented from eluting. Thereby, a lithium nickel composite metal oxide having a high output at a high current rate at a high voltage can be obtained.

<< Fourth Embodiment >>
The present embodiment further includes a refiring step after the drying step in the post-processing step of the second embodiment. That is, 4th Embodiment has a mixing process, a baking process, and a post-processing process (a washing | cleaning process, a drying process, and a rebaking process) in this order.
The description regarding the mixing process, baking process, washing process, drying process, and re-baking process in the present embodiment is the same as the description in the above-described embodiment.

«Fifth embodiment»
The present embodiment further includes a coating step after the cleaning step in the post-processing step of the first embodiment. That is, it has a mixing process, a baking process, and a post-processing process (cleaning process and coating process) in this order. The description regarding the mixing step, the firing step, and the cleaning step in the present embodiment is the same as the description in the first embodiment.

[Coating process]
A cathode active material for a lithium secondary battery is formed by mixing a coating material raw material and a lithium nickel composite metal oxide and forming a coating layer on the surface of secondary particles of the lithium nickel composite metal oxide by heat treatment as necessary. Is obtained.
As the coating material raw material, oxides, hydroxides, carbonates, nitrates, sulfates, halides, oxalates or alkoxides can be used, and oxides are preferable.
Since the coating material raw material is efficiently coated on the surface of the lithium nickel composite metal oxide, the coating material raw material is preferably finer than the secondary particles of the lithium nickel composite metal oxide. Specifically, the average secondary particle diameter of the coating material is preferably 1 μm or less, and more preferably 0.1 μm or less.

  The mixing of the coating material raw material and the lithium nickel composite metal oxide may be performed in the same manner as the mixing at the time of producing the lithium nickel composite metal oxide. A method of mixing using a mixing apparatus that does not include mixing media such as balls and does not involve strong pulverization, such as a method of mixing using a powder mixer equipped with a stirring blade inside, is preferable. Further, the coating layer can be more firmly attached to the surface of the lithium nickel composite metal oxide by being held in an atmosphere containing water after mixing.

  The heat treatment conditions (temperature, holding time) in the heat treatment performed as necessary after mixing the coating material and the lithium nickel composite metal oxide may differ depending on the type of the coating material. The heat treatment temperature is preferably set in the range of 300 to 850 ° C., and is preferably a temperature equal to or lower than the firing temperature of the lithium nickel composite metal oxide. When the temperature is higher than the firing temperature of the lithium nickel composite metal oxide, the coating material raw material may be dissolved in the lithium nickel composite metal oxide and the coating layer may not be formed. The holding time in the heat treatment is preferably set shorter than the holding time at the time of firing. As an atmosphere in the heat treatment, an atmosphere gas similar to that in the above-described firing can be given.

  Further, impurities can be reduced by performing the heat treatment under the above conditions.

  By using a technique such as sputtering, CVD, or vapor deposition, a positive electrode active material for a lithium secondary battery can be obtained by forming a coating layer on the surface of the lithium nickel composite metal oxide.

  Moreover, the positive electrode active material for lithium secondary batteries may be obtained by mixing and baking the said (lithium nickel composite metal oxide), lithium salt, and coating | covering material raw material.

  In the post-treatment process having the cleaning process and the coating process, the impurities can be sufficiently removed by performing the cleaning process and the coating process under the above-described conditions, and lithium is contained in the slurry in the cleaning process. Elution can be suppressed. Thereby, a lithium nickel composite metal oxide having a high output at a high current rate at a high voltage can be obtained.

<< Sixth Embodiment >>
The present embodiment further includes a coating step after the drying step in the post-processing step of the second embodiment. That is, 6th Embodiment has a mixing process, a baking process, and a post-processing process (a washing process, a drying process, and a coating process) in this order. The description regarding the mixing process, the baking process, the cleaning process, the drying process, and the coating process in the present embodiment is the same as the description in the above embodiment.

  In the post-treatment step of the fourth embodiment and the sixth embodiment, the total of residual sulfate radical and residual lithium carbonate of the lithium nickel composite oxide obtained after the drying step is 0.6 mass% or less, and sodium is 50 ppm or less. It is the process of processing to become.

  In the present invention, the second embodiment to the sixth embodiment are preferable, the fourth embodiment to the sixth embodiment are more preferable, and the fourth embodiment or the sixth embodiment is particularly preferable.

<Lithium nickel composite oxide>
The lithium nickel composite oxide produced by the method for producing a lithium nickel composite oxide of the present invention is represented by the general formula (I).
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(In formula (I), 0 <x ≦ 0.2, 0 <y ≦ 0.5, 0 <z ≦ 0.8, 0 ≦ w ≦ 0.1, y + z + w <1, M is Fe, Cu, Ti Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, and V represent one or more metals selected from the group consisting of V.)

From the viewpoint of obtaining a lithium secondary battery with higher initial Coulomb efficiency, x in the general formula (I) is more preferably 0.005 or more, and particularly preferably 0.01 or more. Further, from the viewpoint of obtaining a lithium secondary battery having a higher capacity retention rate, x in the general formula (I) is preferably 0.15 or less, more preferably 0.12 or less, and 0.09. It is particularly preferred that By setting x in the above range, a lithium secondary battery having high initial coulomb efficiency and high capacity retention can be obtained. When x is 0 or less, the capacity may decrease.
The upper limit value and the lower limit value of x can be arbitrarily combined.

Further, from the viewpoint of obtaining a lithium secondary battery having high cycle characteristics, y in the general formula (I) is preferably 0.005 or more, more preferably 0.01 or more, and 0.05 or more. It is particularly preferred. Further, from the viewpoint of obtaining a lithium secondary battery having high thermal stability, y in the general formula (I) is preferably 0.4 or less, more preferably 0.35 or less, and 0.33. It is particularly preferred that
The upper limit value and the lower limit value of y can be arbitrarily combined.

Further, from the viewpoint of obtaining a lithium secondary battery having high cycle characteristics, z in the general formula (I) is preferably 0.005 or more, more preferably 0.01 or more, and 0.015 or more. It is particularly preferred. Further, from the viewpoint of obtaining a lithium secondary battery having high storage characteristics at a high temperature (for example, in an environment of 60 ° C.), z in the general formula (I) is preferably 0.4 or less, and 0.38 or less. Is more preferable, and it is especially preferable that it is 0.35 or less.
The upper limit value and lower limit value of z can be arbitrarily combined.

In the general formula (I), w is preferably more than 0, more preferably 0.0005 or more, and particularly preferably 0.001 or more. In the general formula (I), w is preferably 0.09 or less, more preferably 0.08 or less, and particularly preferably 0.07 or less.
The upper limit value and the lower limit value of w can be arbitrarily combined.

  In the general formula (I), it is preferable that y + z + w ≦ 0.3.

  M in the general formula (I) represents one or more metals selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga and V. .

  Further, from the viewpoint of obtaining a lithium secondary battery having high cycle characteristics, M in the general formula (I) is preferably at least one selected from the group consisting of Ti, Mg, Al, W, B, and Zr. From the viewpoint of obtaining a lithium secondary battery with high thermal stability, it is preferably at least one selected from the group consisting of Al, W, B, and Zr.

The lithium nickel composite oxide produced by the method for producing a lithium nickel composite oxide of the present invention may have a coating layer.
Coating layer comprises a metal composite oxide of Li and M ^2. M ² is at least one selected from Al, Ti, Zr, and W, and is preferably Al. Furthermore, the coating layer is preferably lithium aluminate, more preferably α-lithium aluminate.
In the present embodiment, the coating layer may contain one or more metals selected from the group consisting of Mn, Fe, Co, and Ni.
In this embodiment, the composition of the coating layer can be confirmed by using STEM-EDX element line analysis, inductively coupled plasma emission analysis, electron beam microanalyzer analysis, etc. of the secondary particle cross section. The crystal structure of the coating layer can be confirmed using powder X-ray diffraction or electron beam diffraction.

(Layered structure)
The crystal structure of the lithium nickel composite oxide is a layered structure, and more preferably a hexagonal crystal structure or a monoclinic crystal structure.

The hexagonal crystal structures are P3, P3 ₁ , P3 ₂ , R3, P-3, R-3, P312, P321, P3 ₁ 12, P3 ₁ 21, P3 ₂ 12, P3 ₂ 21, R32, P3m1, P31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P6 ₁ , P6 ₅ , P6 ₂ , P6 ₄ , P6 ₃ , P-6, P6 / m, P6 ₃ / m, P622, P6 ₁ 22, P6 ₅ 22, P6 ₂ 22, P6 ₄ 22, P6 ₃ 22, P6 mm, P6 cc, P6 ₃ cm, P6 ₃ mc, P- It belongs to any one space group selected from the group consisting of 6m2, P-6c2, P-62m, P-62c, P6 / mmm, P6 / mcc, P6 ₃ / mcm, and P6 ₃ / mmc.

The monoclinic crystal structure is P2, P2 ₁ , C2, Pm, Pc, Cm, Cc, P2 / m, P2 ₁ / m, C2 / m, P2 / c, P2 ₁ / c, C2 / It belongs to any one space group selected from the group consisting of c.

  Among these, from the viewpoint of obtaining a lithium secondary battery having a high discharge capacity, the crystal structure is a hexagonal crystal structure belonging to the space group R-3m, or a monoclinic crystal belonging to C2 / m. A crystal structure is particularly preferred.

The lithium compound used in the present invention is not particularly limited as long as it satisfies the above formula (1), and is lithium carbonate, lithium nitrate, lithium sulfate, lithium acetate, lithium hydroxide, lithium oxide, lithium chloride, or lithium fluoride. Any one of them or a mixture of two or more can be used. In these, any one or both of lithium hydroxide and lithium carbonate are preferable.
From the viewpoint of improving the handleability of the positive electrode active material for a lithium secondary battery, the lithium carbonate component contained in the lithium metal composite oxide powder is preferably 0.4% by mass or less, and 0.39% by mass or less. Is more preferable, and it is especially preferable that it is 0.38 mass% or less.
In addition, from the viewpoint of improving the handleability of the positive electrode active material for a lithium secondary battery, the lithium hydroxide component contained in the lithium metal composite oxide powder is preferably 0.4% by mass or less, and 0.39% by mass or less. It is more preferable that it is 0.38 mass% or less.

<Lithium secondary battery>
Next, while explaining the configuration of the lithium secondary battery, a positive electrode active material for a lithium secondary battery using the lithium nickel composite oxide produced by the method for producing a lithium nickel composite oxide of the present invention is used as the lithium secondary battery. A positive electrode used as a positive electrode active material and a lithium secondary battery having the positive electrode will be described.

  An example of the lithium secondary battery of the present embodiment includes a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolyte solution disposed between the positive electrode and the negative electrode.

  FIG. 1 is a schematic diagram showing an example of the lithium secondary battery of the present embodiment. The cylindrical lithium secondary battery 10 of this embodiment is manufactured as follows.

  First, as shown in FIG. 1 (a), a pair of separators 1 having a strip shape, a strip-like positive electrode 2 having a positive electrode lead 21 at one end, and a strip-like negative electrode 3 having a negative electrode lead 31 at one end, 2, separator 1, and negative electrode 3 are laminated in this order and wound to form electrode group 4.

  Next, as shown in FIG. 1B, after the electrode group 4 and an insulator (not shown) are accommodated in the battery can 5, the bottom of the can is sealed, and the electrode group 4 is impregnated with the electrolytic solution 6, An electrolyte is disposed between the negative electrode 3 and the negative electrode 3. Furthermore, the lithium secondary battery 10 can be manufactured by sealing the upper part of the battery can 5 with the top insulator 7 and the sealing body 8.

  As the shape of the electrode group 4, for example, a columnar shape in which the cross-sectional shape when the electrode group 4 is cut in a direction perpendicular to the winding axis is a circle, an ellipse, a rectangle, or a rectangle with rounded corners. Can be mentioned.

  Moreover, as a shape of the lithium secondary battery having such an electrode group 4, a shape defined by IEC 60086 or JIS C 8500, which is a standard for a battery defined by the International Electrotechnical Commission (IEC), can be adopted. . For example, cylindrical shape, square shape, etc. can be mentioned.

  Furthermore, the lithium secondary battery is not limited to the above-described wound type configuration, and may have a stacked type configuration in which a stacked structure of a positive electrode, a separator, a negative electrode, and a separator is repeatedly stacked. Examples of the stacked lithium secondary battery include so-called coin-type batteries, button-type batteries, and paper-type (or sheet-type) batteries.

Hereafter, each structure is demonstrated in order.
(Positive electrode)
The positive electrode of the present embodiment can be produced by first adjusting a positive electrode mixture containing a positive electrode active material, a conductive material and a binder, and supporting the positive electrode mixture on a positive electrode current collector.

(Conductive material)
As the conductive material included in the positive electrode of the present embodiment, a carbon material can be used. Examples of the carbon material include graphite powder, carbon black (for example, acetylene black), and a fibrous carbon material. Since carbon black is fine and has a large surface area, adding a small amount to the positive electrode mixture can improve the conductivity inside the positive electrode and improve the charge / discharge efficiency and output characteristics. Both the binding force between the positive electrode mixture and the positive electrode current collector and the binding force inside the positive electrode mixture are reduced, which causes an increase in internal resistance.

  The proportion of the conductive material in the positive electrode mixture is preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. When a fibrous carbon material such as graphitized carbon fiber or carbon nanotube is used as the conductive material, this ratio can be lowered.

(binder)
As the binder included in the positive electrode of the present embodiment, a thermoplastic resin can be used. Examples of the thermoplastic resin include polyvinylidene fluoride (hereinafter sometimes referred to as PVdF), polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. And fluororesins such as copolymers, propylene hexafluoride / vinylidene fluoride copolymers, tetrafluoroethylene / perfluorovinyl ether copolymers; polyolefin resins such as polyethylene and polypropylene.

  These thermoplastic resins may be used as a mixture of two or more. By using a fluororesin and a polyolefin resin as a binder, the ratio of the fluororesin to the whole positive electrode mixture is 1% by mass or more and 10% by mass or less, and the ratio of the polyolefin resin is 0.1% by mass or more and 2% by mass or less. A positive electrode mixture having both high adhesion to the current collector and high bonding strength inside the positive electrode mixture can be obtained.

(Positive electrode current collector)
As the positive electrode current collector included in the positive electrode of the present embodiment, a band-shaped member made of a metal material such as Al, Ni, and stainless steel can be used. Among these, a material that is made of Al and formed into a thin film is preferable because it is easy to process and inexpensive.

  Examples of the method of supporting the positive electrode mixture on the positive electrode current collector include a method of pressure-molding the positive electrode mixture on the positive electrode current collector. Also, the positive electrode mixture is made into a paste using an organic solvent, and the resulting positive electrode mixture paste is applied to at least one surface side of the positive electrode current collector, dried, pressed and fixed, whereby the positive electrode current collector is bonded to the positive electrode current collector. A mixture may be supported.

  When the positive electrode mixture is made into a paste, usable organic solvents include amine solvents such as N, N-dimethylaminopropylamine and diethylenetriamine; ether solvents such as tetrahydrofuran; ketone solvents such as methyl ethyl ketone; methyl acetate And amide solvents such as dimethylacetamide and N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP).

  Examples of the method of applying the positive electrode mixture paste to the positive electrode current collector include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method.

A positive electrode can be manufactured by the method mentioned above.
(Negative electrode)
The negative electrode included in the lithium secondary battery of this embodiment is only required to be able to dope and dedope lithium ions at a lower potential than the positive electrode, and the negative electrode mixture containing the negative electrode active material is supported on the negative electrode current collector. And an electrode made of a negative electrode active material alone.

(Negative electrode active material)
Examples of the negative electrode active material possessed by the negative electrode include carbon materials, chalcogen compounds (oxides, sulfides, etc.), nitrides, metals, and alloys that can be doped and dedoped with lithium ions at a lower potential than the positive electrode. It is done.

  Examples of carbon materials that can be used as the negative electrode active material include graphites such as natural graphite and artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and organic polymer compound fired bodies.

The oxide can be used as an anode active _material, (wherein, x represents a positive real number) SiO 2, SiO, etc. formula SiO _x oxides of silicon represented _by; TiO 2, TiO, etc. formula TiO _x (wherein , X is a positive real number); oxide of titanium represented by formula VO _x (where x is a positive real number) such as V ₂ O ₅ and VO ₂ ; Fe ₃ O ₄ , Fe ₂ O ₃ , FeO, etc. Iron oxide represented by the formula FeO _x (where x is a positive real number); SnO ₂ , SnO, etc. represented by the formula SnO _x (where x is a positive real number) Oxide of tin; tungsten oxide represented by general formula WO _x (where x is a positive real number) such as WO ₃ and WO ₂ ; lithium and titanium such as Li ₄ Ti ₅ O ₁₂ and LiVO ₂ Or a metal composite oxide containing vanadium. It is possible.

Examples of sulfides that can be used as the negative electrode active material include titanium sulfides represented by the formula TiS _x (where x is a positive real number) such as Ti ₂ S ₃ , TiS ₂ , and TiS; V ₃ S ₄ , VS _2, VS and other vanadium sulfides represented by the formula VS _x (where x is a positive real number); Fe ₃ S ₄ , FeS ₂ , FeS and other formulas FeS _x (where x is a positive real number) Iron sulfide represented; Mo ₂ S ₃ , MoS _{2 and the} like MoS _x (where x is a positive real number) Molybdenum sulfide; SnS _2, SnS and other formula SnS _x (where, a sulfide of tin represented by x is a positive real number; a sulfide of tungsten represented by a formula WS _x (where x is a positive real number) such as WS ₂ ; a formula SbS _x such as Sb ₂ S ₃ (here And x is a positive real number) antimony sulfide; Se ₅ S ₃ , selenium sulfide represented by the formula SeS _x (where x is a positive real number) such as SeS ₂ and SeS.

Examples of the nitride that can be used as the negative electrode active material include Li ₃ N and Li _3-x A _x N (where A is one or both of Ni and Co, and 0 <x <3). And lithium-containing nitrides.

  These carbon materials, oxides, sulfides and nitrides may be used alone or in combination of two or more. These carbon materials, oxides, sulfides and nitrides may be crystalline or amorphous.

  Examples of the metal that can be used as the negative electrode active material include lithium metal, silicon metal, and tin metal.

Examples of alloys that can be used as the negative electrode active material include lithium alloys such as Li—Al, Li—Ni, Li—Si, Li—Sn, and Li—Sn—Ni; silicon alloys such as Si—Zn; Sn—Mn and Sn. It can also be mentioned; -Co, Sn-Ni, Sn -Cu, tin alloys such as _Sn-La; Cu 2 _Sb, alloys such as La 3 _Ni 2 Sn _7.

  These metals and alloys are mainly used alone as electrodes after being processed into a foil shape, for example.

  Among the negative electrode active materials, the potential of the negative electrode hardly changes from the uncharged state to the fully charged state at the time of charging (potential flatness is good), the average discharge potential is low, and the capacity retention rate when repeatedly charged and discharged is For reasons such as high (good cycle characteristics), carbon materials containing graphite as a main component, such as natural graphite and artificial graphite, are preferably used. The shape of the carbon material may be any of a flake shape such as natural graphite, a spherical shape such as mesocarbon microbeads, a fibrous shape such as graphitized carbon fiber, or an aggregate of fine powder.

  The negative electrode mixture may contain a binder as necessary. Examples of the binder include thermoplastic resins, and specific examples include PVdF, thermoplastic polyimide, carboxymethyl cellulose, polyethylene, and polypropylene.

(Negative electrode current collector)
Examples of the negative electrode current collector of the negative electrode include a band-shaped member made of a metal material such as Cu, Ni, and stainless steel. In particular, it is preferable to use Cu as a forming material and process it into a thin film from the viewpoint that it is difficult to make an alloy with lithium and it is easy to process.

  As a method of supporting the negative electrode mixture on such a negative electrode current collector, as in the case of the positive electrode, a method using pressure molding, pasting with a solvent, etc., applying to the negative electrode current collector, drying and pressing. The method of crimping is mentioned.

(Separator)
Examples of the separator included in the lithium secondary battery of the present embodiment include a porous film, a nonwoven fabric, a woven fabric, and the like made of a material such as a polyolefin resin such as polyethylene and polypropylene, a fluororesin, and a nitrogen-containing aromatic polymer. A material having the following can be used. Moreover, a separator may be formed by using two or more of these materials, or a separator may be formed by laminating these materials.

  In the present embodiment, the separator allows the electrolyte to permeate well when the battery is used (during charging / discharging). Therefore, the air resistance according to the Gurley method defined in JIS P 8117 is 50 seconds / 100 cc or more, 300 seconds / 100 cc. Or less, more preferably 50 seconds / 100 cc or more and 200 seconds / 100 cc or less.

  Moreover, the porosity of the separator is preferably 30% by volume or more and 80% by volume or less, more preferably 40% by volume or more and 70% by volume or less. The separator may be a laminate of separators having different porosity.

(Electrolyte)
The electrolyte solution included in the lithium secondary battery of this embodiment contains an electrolyte and an organic solvent.

The electrolyte contained in the electrolyte includes LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (COCF ₃ ), Li (C ₄ F ₉ SO ₃ ), LiC (SO ₂ CF ₃ ) ₃ , Li ₂ B ₁₀ Cl ₁₀ , LiBOB (where BOB is bis (oxalato) borate LiFSI (here, FSI is bis (fluorosulfonyl) imide), lithium salt such as lower aliphatic carboxylic acid lithium salt, LiAlCl _4, and a mixture of two or more of these May be used. Among them, the electrolyte is at least selected from the group consisting of LiPF ₆ containing fluorine, LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ and LiC (SO ₂ CF ₃ ) _3. It is preferable to use one containing one kind.

  Examples of the organic solvent contained in the electrolyte include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, and 1,2-di- Carbonates such as (methoxycarbonyloxy) ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, 2- Ethers such as methyltetrahydrofuran; Esters such as methyl formate, methyl acetate and γ-butyrolactone; Nitriles such as acetonitrile and butyronitrile; N, N-dimethylformamide, N, N-dimethylacetate Amides such as amides; carbamates such as 3-methyl-2-oxazolidone; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide and 1,3-propane sultone, or those obtained by further introducing a fluoro group into these organic solvents ( One obtained by substituting one or more hydrogen atoms in the organic solvent with fluorine atoms can be used.

  As the organic solvent, it is preferable to use a mixture of two or more of these. Among them, a mixed solvent containing carbonates is preferable, and a mixed solvent of cyclic carbonate and acyclic carbonate and a mixed solvent of cyclic carbonate and ether are more preferable. As a mixed solvent of cyclic carbonate and acyclic carbonate, a mixed solvent containing ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is preferable. The electrolyte using such a mixed solvent has a wide operating temperature range, hardly deteriorates even when charged and discharged at a high current rate, hardly deteriorates even when used for a long time, and natural graphite as an active material of the negative electrode. Even when a graphite material such as artificial graphite is used, it has many features that it is hardly decomposable.

Further, as the electrolytic solution, it is preferable to use an electrolytic solution containing a lithium salt containing fluorine such as LiPF ₆ and an organic solvent having a fluorine substituent because the safety of the obtained lithium secondary battery is increased. A mixed solvent containing dimethyl carbonate and ethers having fluorine substituents such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether is capable of capacity even when charging / discharging at a high current rate. Since the maintenance rate is high, it is more preferable.

A solid electrolyte may be used instead of the above electrolytic solution. As the solid electrolyte, for example, an organic polymer electrolyte such as a polyethylene oxide polymer compound, a polymer compound containing at least one of a polyorganosiloxane chain or a polyoxyalkylene chain can be used. Moreover, what is called a gel type which hold | maintained the non-aqueous electrolyte in the high molecular compound can also be used. The _{Li 2 S-SiS 2, Li} 2 S-GeS 2, Li 2 S-P 2 S 5, Li 2 S-B 2 S 3, Li 2 S-SiS 2 -Li 3 PO 4, Li 2 S-SiS _{2 -Li 2 SO 4, Li 2} S-GeS 2 -P 2 S 5 inorganic solid electrolytes containing a sulfide, and the like, may be used a mixture of two or more thereof. By using these solid electrolytes, the safety of the lithium secondary battery may be further improved.

  In the lithium secondary battery of the present embodiment, when a solid electrolyte is used, the solid electrolyte may serve as a separator, and in that case, the separator may not be required.

  Since the positive electrode active material having the above-described configuration uses the above-described lithium metal composite oxide of the present embodiment, the life of the lithium secondary battery using the positive electrode active material can be extended.

  Moreover, since the positive electrode having the above-described configuration has the above-described positive electrode active material for a lithium secondary battery according to this embodiment, the life of the lithium secondary battery can be extended.

  Furthermore, since the lithium secondary battery having the above-described configuration has the above-described positive electrode, the lithium secondary battery has a longer life than the conventional one.

    Next, the present invention will be described in more detail with reference to examples.

In this example, evaluation of a positive electrode active material for a lithium secondary battery and production evaluation of a positive electrode for a lithium secondary battery and a lithium secondary battery were performed as follows.
(1) Evaluation of positive electrode active material for lithium secondary battery 1 Composition analysis of lithium-containing composite metal oxide, measurement of residual sulfate radical and residual lithium sulfate present in lithium-containing composite metal oxide Lithium produced by the method described later Analysis of the composition of the metal-containing composite metal oxide and measurement of the residual sulfate radical and residual lithium sulfate present in the lithium-containing composite metal oxide are obtained by dissolving the obtained lithium-containing composite metal oxide powder in hydrochloric acid and then inductively coupling The measurement was performed using a plasma emission analyzer (manufactured by SII Nanotechnology Inc., SPS3000).

2 Measurement of metal elements present in lithium-containing composite metal oxide An inductively coupled plasma emission analyzer (SPS3000, manufactured by SII Nanotechnology Inc.) was used for analysis by inductively coupled plasma emission spectrometry.

(2) Production of positive electrode for lithium secondary battery A positive electrode active material for lithium secondary battery, a conductive material (acetylene black), and a binder (PVdF) obtained by the production method described later are used as a positive electrode active material for lithium secondary battery: A paste-like positive electrode mixture was prepared by adding and kneading so that the composition of conductive material: binder = 92: 5: 3 (mass ratio) was obtained. When preparing the positive electrode mixture, N-methyl-2-pyrrolidone was used as the organic solvent.

The obtained positive electrode mixture was applied to a 15 μm thick Al foil serving as a current collector and vacuum dried at 60 ° C. for 3 hours to obtain a positive electrode for a lithium secondary battery. The electrode area of the positive electrode for the lithium secondary battery was 1.65 cm ² .

(3) Production of lithium secondary battery (coin type half cell) The following operation was performed in a glove box in a dry air atmosphere.
Place the positive electrode for the lithium secondary battery prepared in “(2) Preparation of the positive electrode for the lithium secondary battery” with the aluminum foil surface facing downward on the lower lid of the part for the coin-type battery R2032 (manufactured by Hosen Co., Ltd.). Then, a laminated film separator (a heat-resistant porous layer laminated on a polyethylene porous film (thickness: 16 μm)) was placed thereon. 300 μl of electrolyte was injected here. The electrolytic solution was ethylene carbonate (hereinafter sometimes referred to as EC), dimethyl carbonate (hereinafter sometimes referred to as DMC), and ethyl methyl carbonate (hereinafter sometimes referred to as EMC) 30:35. : 35 (volume ratio) a mixture of LiPF ₆ dissolved to 1.0 mol / l (hereinafter sometimes referred to as LiPF ₆ / EC + DMC + EMC) was used.
Next, using lithium metal as the negative electrode, the negative electrode is placed on the upper side of the laminated film separator, covered with a gasket, and then caulked with a caulking machine to form a lithium secondary battery (coin type half cell R2032, hereinafter "half cell"). Was prepared.

(4) Discharge capacity Using the half cell produced in "(3) Production of lithium secondary battery (coin-type half cell)", a charge / discharge test was performed under the following conditions.
<Discharge test>
Using the half cell produced in <Preparation of lithium secondary battery (coin-type half cell)>, a discharge rate test was performed under the following conditions. In the discharge rate test, the 3CA discharge capacity retention rate was determined as follows.

<Discharge rate test>
Test temperature 25 ° C
Charge maximum voltage 4.45V, charge time 8 hours, charge current 0.2CA constant current constant voltage charge discharge capacity when discharged at constant current with minimum voltage 2.5V, constant current discharge 0.2CA and discharge at 3CA The 3CA discharge capacity maintenance rate calculated | required by the following formula | equation was calculated | required by calculating | requiring the discharge capacity when letting it be made. A higher 3CA discharge capacity retention rate means higher output.
<3CA discharge capacity maintenance rate>
3CA discharge capacity maintenance rate (%)
= Discharge capacity at 3 CA / discharge capacity at 0.2 CA x 100

Example 1
[Mixing process]
1. Production of lithium nickel composite oxide 1
Fine nickel cobalt manganese aluminum composite hydroxide 1 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 1 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Then, it stood to cool to room temperature, and obtained nickel cobalt manganese aluminum complex oxide 1.
Nickel cobalt manganese aluminum composite oxide 1 and lithium hydroxide powder were weighed and mixed so that Li / (Ni + Co + Mn + Al) = 1.10.

[Baking process]
Then, it baked at 760 degreeC under oxygen atmosphere for 5 hours, and the baked product 1 was obtained.

[Post-processing process]
Then, the post-processing process which has the following washing | cleaning process, a drying process, and a coating process was implemented.

Washing step The fired product 1 was washed with water 11 times as much as the fired product 1.

-Drying process Then, the baked product 1 was dried at 150 degreeC for 12 hours, and the washing | cleaning dry powder 1 was obtained.

・ Coating process Washed and dried powder 1 and aluminum oxide (Alumina C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm, content of Ni, Co, Mn and Al in washed and dried powder 1 is 1 mol. In other words, the ratio of the Al atomic ratio of aluminum oxide to the sum of the atomic ratios of Ni, Co, Mn, and Al in the washed dry powder 1 is 1.5 mol%.) Dry mixing was performed to obtain a mixed powder. The obtained powder was baked at 760 ° C. for 10 hours in an oxygen atmosphere to obtain lithium nickel composite oxide 1.

2. Evaluation of Washed Dry Powder 1 and Lithium Nickel Composite Oxide 1 When composition analysis of washed dry powder 1 was performed and made to correspond to the general formula (1), x = 0.006, y = 0.093, z = 0. 020, w = 0.09.
When the composition analysis of the lithium nickel composite oxide 1 was performed and made to correspond to the general formula (1), x = 0.001, y = 0.093, z = 0.020, and w = 0.022.

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 1 was 85.4%.

(Example 2)
[Mixing process]
1. Production of lithium nickel composite oxide 2
Fine nickel cobalt manganese aluminum composite hydroxide 2 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared as a nickel-containing metal composite compound by a continuous coprecipitation method. . The obtained nickel cobalt manganese aluminum composite hydroxide 2 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 2 was obtained.
Nickel cobalt manganese aluminum composite oxide 2 and lithium hydroxide powder were weighed and mixed so that Li / (Ni + Co + Mn + Al) = 1.10.

[Baking process]
Then, it baked at 760 degreeC under oxygen atmosphere for 5 hours, and the baked product 2 was obtained.

[Post-processing process]
Then, the post-processing process which has the following washing | cleaning process, a drying process, and a rebaking process was implemented.

-Washing process The fired product 2 was washed with 11 times as much water as the fired product 2.

-Drying process Then, the baked product 2 was dried at 150 degreeC for 12 hours, and the washing | cleaning dry powder 2 was obtained.

-Rebaking process Then, the washing | cleaning dry powder 2 was baked at 760 degreeC in oxygen atmosphere for 10 hours, and the lithium nickel composite oxide 2 was obtained.

2. Evaluation of washed dry powder 2 and lithium nickel composite oxide 2
The composition analysis of the washed dry powder 2 was performed and was made to correspond to the general formula (1). As a result, x = 0.007, y = 0.093, z = 0.020, and w = 0.0099.
The composition analysis of the lithium nickel composite oxide 2 was performed, and when it was made to correspond to the general formula (1), x = 0.007, y = 0.094, z = 0.020, and w = 0.09.

  The 3CA discharge capacity retention rate of lithium nickel composite oxide 2 at 4.45 V was 76.4%.

(Example 3)
[Mixing process]
1. Production of lithium nickel composite oxide 3
Fine nickel cobalt manganese aluminum composite hydroxide 3 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 3 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 3 was obtained.
The nickel cobalt manganese aluminum composite oxide 3 and the lithium hydroxide powder were weighed and mixed so that Li / (Ni + Co + Mn + Al) = 1.15.

[Baking process]
Then, it baked at 720 degreeC for 10 hours under oxygen atmosphere, and the baked product 3 was obtained.

[Post-processing process]
Then, the post-processing process which has the following washing | cleaning process, a drying process, and a coating process was implemented.

-Washing process The fired product 3 was washed with water 12 times as much as the fired product 3.

-Drying process Then, the baked product 3 was dried at 150 degreeC for 12 hours, and the washing | cleaning dry powder 3 was obtained.

・ Coating process Washed dry powder 3 and aluminum oxide (Alumina C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm, Ni in the washed dry powder 3, Al content of Al is 1 mol) In other words, the ratio of the atomic ratio of Al in aluminum oxide to the sum of the atomic ratios of Ni, Co, Mn and Al in the washed dry powder 3 is 1.5 mol%.) Dry mixing was performed to obtain a mixed powder. The obtained powder was baked at 760 ° C. for 10 hours in an oxygen atmosphere to obtain a lithium nickel composite oxide 3.

2. Evaluation of washed dry powder 3 and lithium nickel composite oxide 3
The composition analysis of the washed dry powder 3 was performed and was made to correspond to the general formula (1). As a result, x = 0.030, y = 0.094, z = 0.020, and w = 0.0099.
The composition analysis of the lithium nickel composite oxide 3 was performed and made to correspond to the general formula (1). As a result, x = 0.199, y = 0.092, z = 0.020, and w = 0.024.

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 3 was 78.9%.

(Comparative Example 1)
[Mixing process]
1. Production of lithium nickel composite oxide 4
Fine nickel cobalt manganese aluminum composite hydroxide 4 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 4 was heated to 650 ° C. at a temperature rising rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 4 was obtained.
The nickel cobalt manganese aluminum composite oxide 4 and the lithium hydroxide powder were weighed and mixed so that Li / (Ni + Co + Mn + Al) = 1.02.

[Baking process]
Then, it baked at 760 degreeC under oxygen atmosphere for 5 hours, and the baked product 4 was obtained.

[Refiring process]
Thereafter, the fired product 4 was fired at 760 ° C. for 10 hours in an oxygen atmosphere to obtain a lithium nickel composite oxide 4.

2. Evaluation of lithium nickel composite oxide 4
The composition analysis of the lithium nickel composite oxide 4 was performed, and when it was made to correspond to the general formula (1), x = −0.002, y = 0.095, z = 0.020, w = 0.010. .

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 4 was 63.9%.

(Comparative Example 2)
[Mixing process]
1. Production of lithium nickel composite oxide 5
_Fine nickel cobalt manganese aluminum composite hydroxide 5 (Ni _0.855 Co _0.095 Mn _0.02 Al _0.03 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 5 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 5 was obtained.
Nickel cobalt manganese aluminum composite oxide 5 and lithium hydroxide powder were weighed and mixed so that Li / (Ni + Co + Mn + Al) = 1.05.

[Baking process]
Then, it baked at 770 degreeC under oxygen atmosphere for 5 hours, and the baked product 5 was obtained.

[Coating process]
Baked product 5 and aluminum oxide (Alumina C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm, Al content of Ni, Co, Mn and Al in fired product 5 is 0.020 mol of Al. That is, the ratio of the atomic ratio of Al of aluminum oxide to the sum of the atomic ratios of Ni, Co, Mn and Al in the fired product 5 is 2.0 mol%.) A powder was obtained. Then, the mixer atmosphere was controlled to 50 ° C. and relative humidity 100%, and left for 1 hour. The obtained powder was baked at 770 ° C. for 5 hours in an oxygen atmosphere to obtain a lithium nickel composite oxide 5.

2. Evaluation of lithium nickel composite oxide 5
When the composition analysis of the lithium nickel composite oxide 5 was performed and made to correspond to the general formula (1), x = 0.003, y = 0.092, z = 0.020, and w = 0.047.

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 5 was 65.1%.

(Comparative Example 3)
[Mixing process]
1. Production of lithium nickel composite oxide 6
Fine nickel cobalt manganese aluminum composite hydroxide 6 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 6 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 6 was obtained.
Nickel-cobalt-manganese-aluminum composite oxide 6 and lithium hydroxide powder were weighed so that Li / (Ni + Co + Mn + Al) = 1.10 and pulverized with a jet mill (Ni in lithium-nickel composite oxide 6) , Co, Mn, and Al content is 1 mol, and tungsten oxide W is 0.004 mol, that is, tungsten oxide W with respect to the sum of atomic ratios of Ni, Co, Mn, and Al in lithium nickel composite oxide 6. The ratio of the atomic ratio is 0.4 mol%.) Was weighed and mixed.

[Baking process]
Then, it baked at 760 degreeC under oxygen atmosphere for 5 hours, and the baked product 6 was obtained.

[Post-processing process]
Then, the post-processing process which has the following washing | cleaning process, a drying process, and a coating process was implemented.

-Washing process The fired product 6 was washed with water 12 times as much as the fired product 6.

-Drying process Then, the baked product 6 was dried at 150 degreeC for 12 hours, and the washing | cleaning dry powder 6 was obtained.

・ Coating process Washed dry powder 6 and aluminum oxide (Alumina C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm, Ni in the washed dry powder 6 and 1 mol of Al, Al in aluminum oxide is In other words, the ratio of the atomic ratio of Al in aluminum oxide to the sum of the atomic ratios of Ni, Co, Mn and Al in the washed dry powder 6 is 1.5 mol%.) Dry mixing was performed to obtain a mixed powder. The obtained powder was fired at 760 ° C. for 10 hours in an oxygen atmosphere to obtain lithium nickel composite oxide 6.

2. Evaluation of washed dry powder 6 and lithium nickel composite oxide 6
When the composition analysis of the washed dry powder 6 was performed and made to correspond to the general formula (1), x = −0.008, y = 0.093, z = 0.021, and w = 0.09.
The composition analysis of the lithium nickel composite oxide 6 was performed, and when it was made to correspond to the general formula (1), x = −0.016, y = 0.093, z = 0.021, w = 0.023. .

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 6 was 64.7%.

(Comparative Example 4)
[Mixing process]
1. Production of lithium nickel composite oxide 7
Fine nickel cobalt manganese aluminum composite hydroxide 7 (Ni _0.875 Co _0.095 Mn _0.02 Al _0.01 (OH) ₂ ) was prepared by a continuous coprecipitation method as a nickel-containing metal composite compound. . The obtained nickel cobalt manganese aluminum composite hydroxide 7 was heated to 650 ° C. at a heating rate of 100 ° C./hour in a dry air atmosphere using an electric furnace, and held at 650 ° C. for 5 hours. Thereafter, the mixture was allowed to cool to room temperature, and nickel cobalt manganese aluminum composite oxide 7 was obtained.
Nickel-cobalt-manganese-aluminum composite oxide 7 and lithium hydroxide powder were weighed so that Li / (Ni + Co + Mn + Al) = 1.10 and ground with a jet mill (Ni in lithium nickel composite oxide 7) , Co, Mn, and Al content of 1 mol, tungsten oxide W is 0.004 mol, that is, tungsten oxide W with respect to the sum of atomic ratios of Ni, Co, Mn, and Al in lithium nickel composite oxide 7. The ratio of the atomic ratio is 0.4 mol%.) Was weighed and mixed.

[Baking process]
Then, it baked at 760 degreeC under oxygen atmosphere for 5 hours, and the baked product 7 was obtained.

[Post-processing process]
Then, the post-processing process which has the following washing | cleaning process, a drying process, and a coating process was implemented.

-Washing process The fired product 7 was washed with water 22 times as much as the fired product 7.

-Drying process Then, the baked product 7 was dried at 150 degreeC for 12 hours, and the washing | cleaning dry powder 7 was obtained.

-Covering process The calcined product 7 and aluminum oxide (Alumina C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm, the content of Ni, Co, Mn and Al in the washed dry powder 7 is 1 mol, and Al in the aluminum oxide is 0. In other words, the ratio of the atomic ratio of Al in aluminum oxide to the sum of the atomic ratios of Ni, Co, Mn, and Al in the washed dry powder 7 is 1.5 mol%.) Mixed to obtain a mixed powder. The obtained powder was baked at 760 ° C. for 10 hours in an oxygen atmosphere to obtain lithium nickel composite oxide 7.

2. Evaluation of washed dry powder 7 and lithium nickel composite oxide 7
The composition analysis of the washed dry powder 7 was performed, and when it was made to correspond to the general formula (1), x = −0.011, y = 0.094, z = 0.021, and w = 0.09.
The composition analysis of the lithium nickel composite oxide 7 was performed, and when it was made to correspond to the general formula (1), x = −0.019, y = 0.093, z = 0.021, w = 0.024. .

  The 3CA discharge capacity retention rate at 4.45 V of the lithium nickel composite oxide 7 was 68.4%.

The results of Examples 1 to 3 and Comparative Examples 1 to 4 are collectively shown in Table 1. In Table 1 below, “Li / Me” is the molar ratio of lithium in the obtained lithium nickel composite oxide (the molar ratio of lithium to the total amount of nickel, cobalt, manganese, and aluminum). In Table 1 below, “after the drying step” means the analysis result of the washed dry powder after the drying step in the post-treatment step.
In Table 1 below, “after refiring or coating step” means the result of analyzing the lithium nickel composite oxides 1-7.

As shown in Table 1 above, according to Examples 1 to 3 to which the present invention was applied, a lithium nickel composite oxide having a high output at a high current rate at a high voltage could be produced.
On the other hand, the lithium nickel composite oxide manufactured by Comparative Examples 1 to 4 to which the present invention is not applied has a low output at a high current rate at a high voltage. Moreover, since the comparative examples 1-2 which did not perform the post-processing process including a washing | cleaning process have many impurities, it is guessed that the output in the high current rate with a high voltage fell. Although the comparative examples 3-4 performed the post-processing process including a washing | cleaning process, since lithium eluted by overwashing, it is guessed that the output in the high current rate with a high voltage fell.

  DESCRIPTION OF SYMBOLS 1 ... Separator, 2 ... Positive electrode, 3 ... Negative electrode, 4 ... Electrode group, 5 ... Battery can, 6 ... Electrolyte solution, 7 ... Top insulator, 8 ... Sealing body, 10 ... Lithium secondary battery, 21 ... Positive electrode lead, 31 ... Negative electrode lead

Claims (9)

A method for producing a lithium nickel composite oxide represented by the following general formula (I):
A mixing step of mixing a lithium compound and a composite metal compound containing at least nickel to obtain a mixture;
A firing step of firing the mixture to obtain a fired product;
A post-processing step including a cleaning step of cleaning the fired product,
In the mixing step, mixing is performed so that a molar ratio (Li / Me) of lithium contained in the lithium compound and a metal element in the composite metal compound containing at least nickel exceeds 1;
The lithium nickel composite oxide obtained after the post-treatment step is treated so that the total amount of residual sulfate radicals and residual lithium carbonate is 0.3% by mass or less and the sodium content is 50 ppm or less. A process for producing a lithium nickel composite oxide, comprising a step.
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(In formula (I), 0 <x ≦ 0.2, 0 <y ≦ 0.5, 0 <z ≦ 0.8, 0 ≦ w ≦ 0.1, y + z + w <1, M is Fe, Cu, Ti Mg, Al, W, B, Mo, Nb, Zn, Sn, Zr, Ga, and V represent one or more metals selected from the group consisting of V.)   The method for producing a lithium nickel composite oxide according to claim 1, wherein y + z + w ≦ 0.3 in the general formula (I).   The method for producing a lithium nickel composite oxide according to claim 1 or 2, wherein, in the firing step, a firing temperature is 300 ° C or higher and 1000 ° C or lower.   The method for producing a lithium nickel composite oxide according to any one of claims 1 to 3, further comprising a drying step of drying the obtained lithium nickel composite oxide after the cleaning step in the post-treatment step.   The method for producing a lithium nickel composite oxide according to any one of claims 1 to 3, further comprising a refiring step of refiring the obtained lithium nickel composite oxide after the cleaning step in the post-treatment step.   5. The method for producing a lithium nickel composite oxide according to claim 4, wherein the post-treatment step includes a refiring step of refiring the obtained lithium nickel composite oxide after the drying step.   4. The method according to claim 1, further comprising a coating step of mixing the obtained lithium nickel composite oxide and an aluminum compound and coating the surface of the lithium nickel composite oxide with the aluminum compound after the cleaning step. A method for producing the lithium nickel composite oxide according to claim 1.   5. The lithium according to claim 4, wherein the post-treatment step includes a coating step of mixing the obtained lithium nickel composite oxide and an aluminum compound after the drying step and coating the surface of the lithium nickel composite oxide with the aluminum compound. Method for producing nickel composite oxide.   In the post-treatment step, the total amount of residual sulfate radicals and residual lithium carbonate in the lithium nickel composite oxide obtained after the drying step is 0.6% by mass or less, and the sodium content is 50 ppm or less. The manufacturing method of the lithium nickel composite oxide of Claim 6 or 8 processed into.

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