WO2014175191A1

WO2014175191A1 - Composite compound, lithium-containing composite oxide, and methods respectively for producing said products

Info

Publication number: WO2014175191A1
Application number: PCT/JP2014/061081
Authority: WO
Inventors: 河里　健; 昌彦田村
Original assignee: 旭硝子株式会社
Priority date: 2013-04-25
Filing date: 2014-04-18
Publication date: 2014-10-30
Also published as: JP6510402B2; JPWO2014175191A1

Abstract

Provided are: a composite compound which is useful as a precursor of a lithium-containing composite oxide that can achieve a high electrode density even when the pressing pressure applied during production is low, has an excellent electrical discharge capacity per unit area and excellent rate properties and also has extremely superior cycle properties; and others. A composite compound which contains nickel and manganese, and has a ratio of the diameter of 90% cumulative volume (D₉₀) to the diameter of 10% cumulative volume (D₁₀) (i.e., D₉₀/D₁₀) of 2.00 or less in a laser scattering particle size distribution measurement, a tap density of 1.9 g/cm³ or more and an average circularity degree of 0.960 or more.

Description

Composite compound, lithium-containing composite oxide, and production method thereof

The present invention relates to a composite compound useful as a precursor of a lithium-containing composite oxide, and a method for producing the same, a lithium-containing composite oxide, and a method for producing the same, a method for producing a positive electrode for a lithium ion secondary battery, and a lithium ion secondary The present invention relates to a battery manufacturing method.

Lithium ion secondary batteries are widely used in portable electronic devices such as mobile phones and notebook computers. Examples of the positive electrode active material for the lithium ion secondary battery include composite oxides of lithium and transition metals such as LiCoO ₂ , LiNiO ₂ , LiNi _0.8 Co _0.2 O ₂ , and LiMn ₂ O ₄ (hereinafter, "Sometimes referred to as" lithium-containing composite oxide ").

In recent years, lithium ion secondary batteries used for portable electronic devices, in-vehicle use, and the like are required to be smaller and lighter, and to be usable for a long time. Therefore, the positive electrode active material has a further improvement in the discharge capacity per unit volume and the characteristics that the discharge capacity does not decrease after repeated charge / discharge cycles (hereinafter, sometimes referred to as “cycle characteristics”), and safety. There is a need for compatibility with sex. In particular, if the cycle characteristics are insufficient, for example, in a portable electronic device, the usable time in one charge decreases with time, so the commercial value of the portable electronic device decreases. Therefore, improvement in cycle characteristics is strongly demanded.

The discharge capacity per unit volume is determined by the discharge capacity per unit mass and the packing density of the positive electrode active material. Therefore, in order to improve the packing density of the positive electrode active material in the positive electrode (hereinafter sometimes referred to as “electrode density”), it has been studied to control the particle size and particle size distribution of the positive electrode active material. In addition, in order to improve the packing density of the positive electrode active material in the positive electrode, it has been studied to control the shape of the positive electrode active material particles into a spherical shape or a plate shape.

Patent Document 1 proposes a technique for improving the press density by setting the ratio of particles of 10 μm or less to 26 to 60% by volume in the volume-based particle size distribution of the positive electrode active material. However, this proposed technique has a problem that the average particle size of the positive electrode active material is large, so that the diffusion of lithium is delayed, the rate characteristics are lowered, and the proportion of fine particles is increased, so that the safety is lowered.

Patent Document 2 proposes a technique for mixing large and small positive electrode active material particles having different compositions and particle sizes. However, this proposed technique requires a step of individually synthesizing two kinds of positive electrode active materials and a step of mixing them, and there is a problem that the manufacturing process is complicated.

Patent Document 3 discloses that a positive electrode is obtained by thermally decomposing particles having a ratio of a short axis particle diameter to a long axis particle diameter (short axis particle diameter / long axis particle diameter) in the range of 0.5 to 1.0. A technique has been proposed in which crystallites and particles in an active material are three-dimensionally approximately isotropic. However, this proposed technique has a problem that the obtained particles are not sufficiently spherical and a sufficient packing density cannot be obtained.

Patent Document 4 proposes a technique for improving the filling properties by including particles having a positive correlation between the particle diameter of the positive electrode active material and the average circularity. However, in this proposed technique, particles with a high average circularity and particles with a low average circularity coexist, so the volume change due to lithium insertion / extraction is not isotropic. There is a problem in the cycle characteristics such as the occurrence. Furthermore, the presence of small particles having a large specific surface area increases the reactivity, which poses a safety problem.

As another method for improving the packing density of the positive electrode active material in the positive electrode, for example, there is a method of applying a high pressure when manufacturing the positive electrode. However, this method requires a robust manufacturing facility that can withstand high pressures. In addition, the manufactured positive electrode is easily cut off, and there is a problem that the yield is lowered and the safety is lowered when used for a lithium ion secondary battery.

Japanese Unexamined Patent Publication No. 2012-121805 Japanese Unexamined Patent Publication No. 2012-74246 Japanese Unexamined Patent Publication No. 2003-346809 Japanese Unexamined Patent Publication No. 2009-283353

The present invention is capable of producing a high-density electrode even when the pressing pressure when forming the positive electrode active material-containing layer is low, and is excellent in discharge capacity per unit volume, rate characteristics, and extremely excellent cycle characteristics. It is an object of the present invention to provide a composite compound that is useful as a precursor of a contained composite oxide, and a production method thereof. Moreover, this invention makes it a subject to provide the lithium containing complex oxide using the said complex compound, and its manufacturing method. Furthermore, this invention makes it a subject to provide the manufacturing method of the positive electrode for lithium ion secondary batteries using the said lithium containing complex oxide, and the manufacturing method of a lithium ion secondary battery using the said positive electrode.

As a result of intensive studies to solve the above problems, the present inventors have found that the shape and particle size distribution of the lithium-containing composite oxide are greatly different from the shape and particle size distribution of the composite compound that is a precursor of the lithium-containing composite oxide. Found to be affected.
The present invention provides a composite compound having the following configuration, a method for producing the same, a lithium-containing composite oxide, a method for producing the same, a method for producing a positive electrode for a lithium ion secondary battery, and a method for producing a lithium ion secondary battery. To do.

[1] It contains nickel and manganese, and the ratio (D ₉₀ / D ₁₀ ) of volume-based cumulative 90% diameter (D ₉₀ ) and volume-based cumulative 10% diameter (D ₁₀ ) in laser scattering particle size distribution measurement is 2. A composite compound characterized by having a tap density of 1.9 g / cm ³ or more and an average circularity of 0.960 or more.
[2] The composite compound according to [1], which is a hydroxide.
[3] The composite compound according to the above [1] or [2], wherein the volume-based cumulative 50% diameter (D ₅₀ ) is 5.0 to 13.0 μm.
[4] The composite compound according to any one of [1] to [3], further containing cobalt.
[5] The content of nickel in the composite compound is 44 to 68 mol%, the content of manganese is 22 to 44 mol%, and the content of cobalt is 4 to 28 mol based on the total of nickel, manganese and cobalt. % Of the composite compound according to the above [4].
[6] A method for producing a composite compound according to any one of [1] to [5] above,
An aqueous solution containing nickel and manganese and an alkali are continuously added to the first reaction vessel to precipitate the core particles, and a core particle-containing liquid preparation step for obtaining a core particle-containing liquid containing the core particles;
A moving step of continuously transferring a part of the core particle-containing liquid in the first reaction vessel from the first reaction vessel to the second reaction vessel;
To the second reaction vessel containing the core particle-containing liquid, an aqueous solution containing nickel and manganese and an alkali are continuously added to grow the core particles, and a part of water is obtained from the obtained reaction liquid. A method for producing a composite compound, comprising a particle growth step to be removed.
[7] The method for producing a complex compound according to the above [6], wherein the transfer step is a step of transferring the core particle-containing liquid overflowing from the first reaction vessel to the second reaction vessel.
[8] A mixing step of mixing the lithium compound and the composite compound according to any one of [1] to [5] to obtain a mixture;
A method for producing a lithium-containing composite oxide, comprising a firing step of firing the mixture.
[9] The method for producing a lithium-containing composite oxide according to the above [8], wherein the lithium-containing composite oxide is a compound represented by the following general formula (1).
_{_{_{_{Li a Ni x Mn y Co z}}}} Me b O c F d ··· formula (1)
However, in the general formula (1), 1.02 ≦ a ≦ 1.12, 0 <x ≦ 1.0, 0 <y ≦ 1.0, 0 ≦ z ≦ 1.0, 0 ≦ b ≦ 0. 3, 0.90 ≦ x + y + z + b ≦ 1.05, 1.9 ≦ c ≦ 2.1, and 0 ≦ d ≦ 0.03, and Me is composed of Mg, Ca, Sr, Ba, Al, and Zr It is at least one selected from the group.
[10] A lithium-containing composite oxide obtained by the method for producing a lithium-containing composite oxide according to [8] or [9].
[11] The lithium-containing composite oxide according to the above [10], wherein the tap density is 1.9 g / cm ³ to 3.0 g / cm ³ and the average circularity is 0.950 or more.
[12] A coating solution containing the lithium-containing composite oxide according to the above [10] or [11], a binder, a conductive material, and a solvent is applied onto the positive electrode current collector, and the lithium-containing composite A method for producing a positive electrode for a lithium ion secondary battery, comprising forming a positive electrode active material-containing layer containing an oxide, a binder, and a conductive material.
[13] The method for producing a positive electrode for a lithium ion secondary battery according to the above [12], comprising a pressurizing step of applying a pressure of 1 t / cm or less to the positive electrode active material-containing layer.
[14] A positive electrode manufacturing step of manufacturing a positive electrode;
A laminate production step of producing a laminate by laminating the positive electrode, the separator, and the negative electrode;
Including a nonaqueous electrolyte application step of containing a nonaqueous electrolyte in the laminate,
The method for producing a lithium ion secondary battery, wherein the positive electrode preparation step is the method for producing a positive electrode for a lithium ion secondary battery according to the above [12] or [13].

According to the present invention, the conventional problems can be solved, and even when the press pressure when forming the positive electrode active material-containing layer is low, a high-density electrode can be produced, the discharge capacity per unit volume, and It is possible to provide a composite compound useful as a precursor of a lithium-containing composite oxide that has excellent rate characteristics and extremely excellent cycle characteristics, and a method for producing the same. Moreover, according to this invention, the lithium containing complex oxide using the said complex compound and its manufacturing method can be provided. Furthermore, according to this invention, the manufacturing method of the positive electrode for lithium ion secondary batteries using the said lithium containing complex oxide and the manufacturing method of a lithium ion secondary battery using the said positive electrode can be provided.

1 is a volume particle size distribution curve of the composite compound of Example 1 and Comparative Example 1. FIG. FIG. 2 is a graph showing the relationship between the tap density of the composite compound in Examples 1 to 5 and Comparative Examples 1 to 6 and the tap density of the lithium-containing composite oxide.

In the present specification, the “precursor” refers to a compound capable of obtaining a lithium-containing composite oxide by mixing and baking with a lithium compound described later.
(Composite compound)
The composite compound of the present invention (hereinafter referred to as the present composite compound) contains at least nickel (Ni) and manganese (Mn), and further contains other components as necessary.
This composite compound has a ratio (D ₉₀ / D ₁₀ ) of a volume-based cumulative 90% diameter (D ₉₀ ) and a volume-based cumulative 10% diameter (D ₁₀ ) in laser scattering particle size distribution measurement of 2.00 or less, The tap density is 1.9 g / cm ³ or more, and the average circularity is 0.960 or more.
In addition, this composite compound is a precursor of lithium containing composite oxide, Comprising: It is a compound which does not contain lithium.
The molar ratio of Ni and Mn (Ni / Mn) in the composite compound is preferably 1.5 to 3.0, and more preferably 1.65 to 2.05.

The composite compound preferably further contains cobalt (Co) in order to improve rate characteristics.
In this composite compound, the greater the amount of Ni, the greater the capacity of the lithium-containing composite oxide obtained using this, but the safety is reduced. Therefore, the content of Ni is preferably 44 to 68 mol% and more preferably 48 to 58 mol% with respect to the total of Ni, Mn and Co in the composite compound.
In this composite compound, Mn does not contribute to the charge / discharge capacity, but maintains a layered structure. Therefore, the content of Mn is preferably 22 to 44 mol% and more preferably 26 to 36 mol% with respect to the total of Ni, Mn and Co of the present composite compound.
In this composite compound, when a small amount of Co is present, the rate characteristics of the lithium-containing composite oxide obtained by using it are improved. Therefore, the Co content is preferably 4 to 28 mol% and more preferably 16 to 24 mol% with respect to the total of Ni, Mn and Co in the present composite compound.

The contents of Ni, Mn and Co in the composite compound can be measured, for example, by dissolving the composite compound in an acid and measuring the obtained liquid by ICP (high frequency inductively coupled plasma).
The other component contained in the composite oxide is at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), aluminum (Al), and zirconium (Zr). Is preferred.
Examples of the composite compound include carbonates, acetates, hydroxides, oxyhydroxides, and mixtures thereof. The composite compound is preferably a hydroxide because the tap density can be increased.

As this composite compound, Mn _0.5 Ni _0.5 (OH) ₂ , Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ , Ni _0.6 Co _0.2 Mn _0.2 (OH ₂ ) and the like.
(D ₉₀ / D ₁₀ ) of the composite compound is 2.00 or less, preferably 1.70 to 1.98, more preferably 1.80 to 1.95. Of the complex compound _{(D 90 /} D _10), since it is 2.00 or less, a lithium-containing composite oxide obtained using the complex compound is excellent in cycle characteristics. If (D ₉₀ / D ₁₀ ) is within the above preferred range, it is advantageous because the electrode density can be increased.
The volume-based cumulative 50% diameter (D ₅₀ ) in the laser scattering particle size distribution measurement of the composite compound is preferably 5.0 to 13.0 μm, more preferably 6.0 to 12.0 μm, from the viewpoint of rate characteristics. A thickness of 0.0 to 10.0 μm is particularly preferable.

Here, D ₁₀ , D ₅₀ , and D ₉₀ are particle size distributions obtained on a volume basis, and in the cumulative curve with the total volume of 100%, the cumulative curve is 10%, 50%, And the particle diameter at the point of 90%.
D _{10, D} _50, and D ₉₀ are, for example, can be determined using the frequency distribution and cumulative volume distribution curve measured by a laser scattering particle size distribution measuring apparatus. The measurement is performed by sufficiently dispersing the powder in an aqueous medium by ultrasonic treatment or the like. Examples of the device include a laser diffraction / scattering particle size distribution measuring device (device name: MT-3300EX) manufactured by Nikkiso Co., Ltd., a laser diffraction / scattering particle size distribution measuring device Partica LA-950VII manufactured by Horiba, Ltd., Nikkiso For example, Microtrac HRA (X-100) manufactured by KK

The tap density of the composite compound is 1.9 g / cm ³ or more, preferably 1.9 ~ 2.8g / cm ^3, more preferably ^{2.0 ~ 2.4g / cm 3, 2.0} ~ 2 .2 g / cm ³ is particularly preferred. Since this composite compound has a tap density of 1.9 g / cm ³ or more, the lithium-containing composite oxide obtained using this composite oxide is excellent in cycle characteristics. It is advantageous that the tap density is within the above-described preferable range because the electrode density can be increased.
The tap density can be obtained by dividing the mass of the sample filled in the container by the volume of the sample after tapping a predetermined number of times. The tap density is obtained by tapping 700 times, for example. The tap density can be measured using, for example, a tap denser KYT-4000 manufactured by Seishin Enterprise Co., Ltd.

The average circularity of the composite compound is 0.960 or more, preferably 0.960 to 0.990, and more preferably 0.960 to 0.980. Since this composite compound has an average circularity of 0.960 or more, the lithium-containing composite oxide obtained using this composite compound is excellent in cycle characteristics. If the average circularity is within the above-described preferable range, it is advantageous because the electrode density can be increased.
The circularity is obtained by photographing a particle and dividing the circumference of a circle equivalent to the projected particle projection area by the circumference of the photographed particle image. The average circularity is an average value of circularity of photographed particles. The average circularity is measured, for example, by dispersing the particles in an aqueous medium by ultrasonic treatment or the like, and irradiating the particles passing through the flow cell with stroboscopic light so that the particles are photographed as a still image and analyzed. Is done. The average circularity can be obtained, for example, by analyzing a particle image obtained using a flow type particle image analyzer (manufactured by Malvern, FPIA-3000).

The specific surface area of the complex compound is preferably 3.0 ~ 12.0m ² / g, more preferably 4.0 ~ 10.0m ² / g, particularly preferably 5.0 ~ 8.0m ² / g. If the specific surface area is 3.0 m ² / g or more, the capacity per mass is excellent, and if it is 12.0 m ² / g or less, the electrode density can be increased. When the specific surface area is within the above-mentioned preferable range, it is advantageous in that the rate characteristics are excellent.
The specific surface area can be measured by, for example, the BET method using nitrogen gas.

(Production method of composite compound)
The method for producing a composite compound of the present invention (hereinafter referred to as the present production method) includes at least a core particle-containing liquid preparation step, a transfer step, and a particle growth step, and further includes other steps as necessary.

<Nucleic particle-containing liquid preparation process>
In the core particle-containing liquid preparation step, an aqueous solution containing Ni and Mn (hereinafter referred to as an aqueous solution (1)) and an alkali are continuously added to the first reaction vessel to precipitate the core particles, Is a step of obtaining a core particle-containing liquid containing
In the core particle-containing liquid preparation step, Ni, Mn, and Co have different solubility when the pH is changed, and thus may segregate when the core particles are precipitated. In the core particle-containing liquid preparation step, it is preferable to continuously add a complexing agent that stabilizes metal ions in order to uniformly precipitate a plurality of metal elements having different solubilities.
Examples of a method for continuously adding the aqueous solution (1) and the alkali to the first reaction vessel include dropping and a method of pumping from a pipe inserted into the reaction solution.

The aqueous solution (1) is further preferably an aqueous solution containing Co.
The aqueous solution (1) can be obtained by dissolving a nickel compound and a manganese compound, and preferably a cobalt compound, in an aqueous medium. The aqueous medium may contain only water or components other than water in addition to water. Examples of components other than water include methanol, ethanol, 1-propanol, 2-propanol, and polyol. Examples of the polyol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, butanediol, glycerin and the like.

Components other than water are preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 1% by mass or less, and most preferably not contained with respect to the aqueous medium. If there are few ratios of components other than water, it is excellent in terms of an environment, handleability, and cost.
Examples of the nickel compound, manganese compound, and cobalt compound include inorganic salts, oxides, hydroxides, and organic compounds containing each element. Examples of inorganic salts include sulfates, nitrates, and carbonates. Examples of the oxide include NiO, Mn ₃ O ₄ , Mn ₂ O ₃ , MnO ₂ , CoO, Co ₂ O ₃ , and Co ₃ O ₄ . Examples of the hydroxide include Ni (OH) ₂ , Mn (OH) ₂ , and Co (OH) ₂ . Examples of the organic compound include fatty acid nickel, manganese citrate, fatty acid manganese, Co (OAc) _{2 and the} like. Among these, sulfate is preferable because of its high solubility and low corrosiveness to equipment.

The nickel compound, manganese compound, and cobalt compound may be the same type of compound or different types of compounds.
The content of the nickel compound in the aqueous solution (1) is preferably 1.0 to 4.0 mol / L, more preferably 1.5 to 3.5 mol / L, and particularly preferably 2.0 to 3.0 mol / L. .

The manganese compound content in the aqueous solution (1) is preferably 0.3 to 2.0 mol / L, more preferably 0.5 to 1.5 mol / L, and particularly preferably 0.7 to 1.3 mol / L. .

When the aqueous solution (1) contains Co, the content of the cobalt compound in the aqueous solution (1) is preferably 0.5 to 3.0 mol / L, more preferably 1.0 to 2.5 mol / L. 2 to 2.0 mol / L is particularly preferable.

The addition amount when the aqueous solution (1) is continuously added to the first reaction vessel is preferably 0.1 to 3.0 L / hour, more preferably 0.5 to 2.0 L / hour. Particularly preferred is 0 to 1.5 L / hour.

Examples of the alkali include a hydroxide or carbonate containing an alkali metal element. Specific examples include sodium hydroxide, lithium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate and the like. The alkali is preferably used in the form of an aqueous solution, that is, as an alkaline aqueous solution.
The concentration of the alkaline aqueous solution is preferably 1 to 12 mol / kg, more preferably 6 to 12 mol / kg.

The amount of alkali added continuously to the first reaction vessel is preferably 0.01 to 0.5 L / hour, more preferably 0.02 to 0.1 L / hour as an aqueous alkali solution.

As the complex-forming agent, any compound that forms a complex with Ni and Mn may be used, and examples thereof include ammonia, ammonium sulfate, ammonium bicarbonate, and ammonium bicarbonate. The amount (molar ratio) of the complexing agent with respect to the total amount of Ni, Co, Mn and the other components is preferably 0.01 to 10, and preferably 0.1 to 1 in order to suppress segregation of the metal in the particles. More preferred.

The core particle-containing liquid preparation step is preferably performed while maintaining the pH in the first reaction vessel at 11.0 to 13.5, and more preferably at 12.0 to 13.0. If the pH in the reaction vessel is maintained at 11.0 to 13.5, the contact between the aqueous solution (1) and the alkali occurs quickly, and the generation of core particles is dominant, which is preferable. The core particles are preferably hydroxides.

The core particle-containing liquid preparation step is preferably performed at a temperature in the first reaction vessel of 45 to 70 ° C.

In the core particle-containing liquid preparation step, water may be placed in the first reaction vessel before the aqueous solution (1) and alkali are continuously added to the first reaction vessel. Examples of water include ion exchange water.

<Transfer process>
The moving step is a step of continuously transferring a part of the core particle-containing liquid in the first reaction vessel from the first reaction vessel to the second reaction vessel. As a specific method of the transfer step, a method of transferring the nuclear particle-containing liquid overflowing from the first reaction vessel to the second reaction vessel, a pipe is provided in the upper part of the first reaction vessel, and the nucleus is passed through the pipe. Examples thereof include a method of transferring the particle-containing liquid to the second reaction vessel. Among these, the method of transferring the core particle-containing liquid overflowing from the first reaction vessel to the second reaction vessel is preferable because it is simple.

<Particle growth process>
In the particle growth step, an aqueous solution containing Ni and Mn (hereinafter referred to as aqueous solution (2)) and an alkali are continuously added to a second reaction vessel containing the nuclear particle-containing liquid to grow the nuclear particles. Meanwhile, this is a step of removing a part of the supernatant from the obtained reaction solution. Also in the particle growth step, it is preferable to continuously add a complexing agent for the same reason as in the core particle-containing liquid preparation step.

The aqueous solution (2) may be the same aqueous solution as the aqueous solution (1) used in the core particle-containing liquid preparation step. The method and amount of continuous addition are the same.

The alkali is the same as the alkali used in the core particle-containing liquid preparation step, and the method and amount of continuous addition are also the same.

The complexing agent is the same as the complexing agent used in the core particle-containing liquid preparation step.

The aqueous solution (2) and alkali are continuously added to the second reaction vessel to grow the core particles.

In the particle growth process, a part of water is removed from the obtained reaction liquid while growing the core particles. Examples of the method for removing water include filtration.

The particle growth step is preferably performed while maintaining the pH in the second reaction vessel at 9.0 to 11.5, and more preferably at 9.5 to 10.5. If the pH in the reaction vessel is maintained at 9.0 to 11.5, it is preferable that the particle growth reaction proceeds easily.

The particle growth step is preferably performed at a temperature in the second reaction vessel of 20 to 40 ° C.
There is no restriction | limiting in particular in the reaction time in a particle growth process, According to the magnitude | size of the target particle | grain, it can select suitably.

In the manufacturing method of the composite compound, in the core particle-containing liquid preparation step, the growth of the formed core particles is suppressed, and the solid content concentration of the core particle-containing liquid is set to the core particle in order to suppress the bonding between the core particles. It is maintained to such an extent that bonding between them can be suppressed.
In the particle growth process, the supernatant liquid is partially removed from the reaction liquid to gradually increase the solid content concentration of the reaction liquid to increase the average circularity of the particles, and the particle size is uniform and has a sharp particle size distribution. Particles of the composite compound of the invention can be obtained.

(Lithium-containing composite oxide and method for producing lithium-containing composite oxide)
The method for producing a lithium-containing composite oxide of the present invention includes at least a mixing step and a firing step.
The lithium-containing composite oxide of the present invention is obtained by the method for producing a lithium-containing composite oxide of the present invention.
The lithium-containing composite oxide is a composite oxide that can be used as a positive electrode active material of a lithium ion secondary battery.

The lithium-containing composite oxide obtained by the method for producing a lithium-containing composite oxide of the present invention is manufactured using this composite compound. Since this composite compound has a large tap density and a high average circularity of the particles, the lithium-containing composite oxide has a high tap density and an average circularity. As a result, the coating slurry containing the lithium-containing composite oxide has a low viscosity. Therefore, handling is easy and the solid content concentration in the slurry can be increased. Furthermore, a battery having a large electrode density formed on a current collector substrate and a large capacity per unit volume can be produced. Furthermore, since the average circularity is high and the particle size is uniform, the expansion and contraction of the electrode during charging and discharging is isotropic, so that the conductive path is not easily cut off and peeled off from the current collector. In addition to excellent properties, the cycle characteristics are very excellent.

<Mixing process>
The mixing step is a step of obtaining a mixture by mixing the lithium compound and the present composite compound.

The lithium compound serves as a lithium source for the lithium-containing composite oxide, and lithium hydroxide, lithium carbonate, lithium nitrate, and the like can be used.
The lithium compound used in the mixing step is a compound different from the lithium-containing composite oxide.

There is no restriction | limiting in particular as a mixing method, According to the objective, it can select suitably.
The amount of the lithium compound in the mixing is such that the molar ratio of lithium (Li) contained in the lithium compound (Li / Ni + Mn + Co) is 1.02 to 1.12 with respect to the total of Ni, Mn and Co contained in the composite compound. Is preferable, and an amount of 1.03 to 1.07 is more preferable.

<Baking process>
A baking process is a process of baking the said mixture.
The firing temperature is preferably 870 to 970 ° C, more preferably 890 to 940 ° C.
The firing atmosphere is preferably an oxygen-containing atmosphere. Examples of the oxygen-containing atmosphere include an air atmosphere.

<Lithium-containing composite oxide>
The lithium-containing composite oxide is preferably a compound represented by the following general formula (1).
_{_{_{_{Li a Ni x Mn y Co z}}}} Me b O c F d ··· formula (1)
However, in the general formula (1), 1.02 ≦ a ≦ 1.12, 0 <x ≦ 1.0, 0 <y ≦ 1.0, 0 ≦ z ≦ 1.0, 0 ≦ b ≦ 0. 3, 0.90 ≦ x + y + z + b ≦ 1.05, 1.9 ≦ c ≦ 2.1, and 0 ≦ d ≦ 0.03, and Me is composed of Mg, Ca, Sr, Ba, Al, and Zr It is at least one selected from the group.

Examples of the lithium-containing composite oxide include LiMn _0.5 Ni _0.5 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , Li _{_{_{_{1.02 Ni 0.49 Co 0.196 Mn 0.294 O}}}} 2, Li 1.04 Ni 0.480 Co 0.192 Mn 0.288 O 2, LiNi 0.6 Co 0.2 Mn 0.2 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O _1.99 F _{0.01 and the} like.

The kind and ratio of the metal element in the lithium-containing composite oxide can be measured, for example, by ICP measurement in the same manner as the composite compound.

The volume-based cumulative 50% diameter (D ₅₀ ) in laser scattering particle size distribution measurement of the lithium-containing composite oxide is preferably 5 to 20 μm, more preferably 6 to 13 μm, and particularly preferably 7 to 10 μm. D ₅₀ is equal to or 5μm or more, the electrode density is sufficiently high, if 20μm or less, it is advantageous from the viewpoint of excellent charge-discharge efficiency and rate characteristics.

The ratio (D ₉₀ / D ₁₀ ) of the volume-based cumulative 90% diameter (D ₉₀ ) and the volume-based cumulative 10% diameter (D ₁₀ ) in the laser scattering particle size distribution measurement of the lithium-containing composite oxide is 2.10 or less. Preferably, 2.00 or less is more preferable. If (D ₉₀ / D ₁₀ ) of the lithium-containing composite oxide is 2.10 or less, it is advantageous in that the tap density is improved and the filling property is improved.

The tap density of the lithium-containing composite oxide is preferably 1.9 ~ 3.0g / cm ^3, more preferably 2.0 ~ 2.7g / cm ^3. If the tap density is 1.9 g / cm ³ or more, the electrode density is sufficiently high, and if the tap density is 3.0 g / cm ³ or less, the electrolyte easily penetrates into the particles, and battery characteristics such as rate characteristics are obtained. This is advantageous in terms of improvement.

The average circularity of the lithium-containing composite oxide is preferably 0.950 or more, and more preferably 0.960 or more. If the average circularity is 0.950 or more, it is advantageous in that the tap density is excellent, the filling property, and the expansion and contraction of the electrode are isotropic.

The specific surface area of the lithium-containing composite oxide is preferably 0.10 ~ ^10m 2 / g, more preferably 0.20 ~ 1.0m ² / g. If the specific surface area is within a preferred range, it is advantageous in that a high positive electrode active material-containing layer having a high discharge capacity is obtained and cycle characteristics are excellent.

The residual alkali amount of the lithium-containing composite oxide is preferably 1.50 mol% or less, and more preferably 1.30 mol% or less. If the residual alkali amount is 1.50 mol% or less, it is advantageous in that gelation of the slurry can be suppressed during electrode coating.
The residual alkali amount is a value (mol%) representing the amount of alkali eluted in water from 1 mol of Li in the lithium-containing composite oxide when the lithium-containing composite oxide is dispersed in water.

(Method for producing positive electrode for lithium ion secondary battery)
The manufacturing method of the positive electrode for lithium ion secondary batteries of this invention contains a positive electrode active material content layer formation process at least, Preferably a pressurization process is included.

<Positive electrode active material-containing layer forming step>
The positive electrode active material-containing layer forming step is a step of forming a positive electrode active material-containing layer containing a lithium-containing composite oxide, a binder, and a conductive material. Specifically, there is a method in which a coating liquid containing a lithium-containing composite oxide, a binder, a conductive material, and a solvent is applied onto the positive electrode current collector.

Examples of the binder include fluororesins, polyolefins, polymers and copolymers having an unsaturated bond, acrylic acid polymers and copolymers, and the like. Examples of the fluororesin include polyvinylidene fluoride and polytetrafluoroethylene. Examples of the polyolefin include polyethylene and polypropylene. Examples of the polymer having an unsaturated bond include styrene / butadiene rubber, isoprene rubber, and butadiene rubber. Examples of acrylic acid polymers include acrylic acid polymers and methacrylic acid polymers.

Examples of the conductive material include carbon black, graphite, and carbon fiber. Examples of the carbon black include acetylene black and ketjen black.

Examples of the solvent in the coating solution include N-methylpyrrolidone.

Examples of the material of the positive electrode current collector include stainless steel, aluminum, aluminum alloy, copper, and nickel.

Application methods include doctor blade coating.

The thickness of the positive electrode active material-containing layer is preferably 20 to 80 μm, more preferably 30 to 50 μm.

<Pressurization process>
The pressurizing step is a step of pressurizing the positive electrode active material-containing layer formed on the positive electrode current collector with a roll press or the like in the positive electrode active material-containing layer forming step. The pressurizing pressure is preferably 1 t (ton) / cm or less, and more preferably 0.5 t / cm or less. The pressurizing pressure is preferably 0.1 t / cm or more.

The lithium-containing composite oxide of the present invention provides a positive electrode active material-containing layer having a high electrode density even when the pressure applied is low in the production of the positive electrode. Since the pressurizing pressure is low, a strong manufacturing facility that can withstand the high pressure is unnecessary. Moreover, it is thought that the decrease in the yield due to the damage of the positive electrode when manufacturing the positive electrode can be suppressed and the decrease in the safety when used for the lithium ion secondary battery can be suppressed because the pressurization pressure is low. .

(Method for producing lithium ion secondary battery)
The method for producing a lithium ion secondary battery of the present invention includes at least a positive electrode preparation step, a laminate preparation step, and a nonaqueous electrolyte application step.

<Positive electrode fabrication process>
A positive electrode preparation process is a process of producing a positive electrode, and is a manufacturing method of the positive electrode for lithium ion secondary batteries of this invention.

<Laminate production process>
The laminate production step is not particularly limited as long as it is a step of producing a laminate by laminating the positive electrode, the separator, and the negative electrode, and can be appropriately selected according to the purpose.

Examples of the material for the separator include paper, cellophane, polyolefin nonwoven fabric, polyamide nonwoven fabric, glass fiber nonwoven fabric, and porous polypropylene. Examples of the paper include kraft paper, vinylon mixed paper, and synthetic pulp mixed paper.
The shape of the separator is a sheet shape. The structure of the separator may be a single layer structure or a laminated structure.

The negative electrode contains at least a negative electrode current collector and a negative electrode active material-containing layer.

Examples of the material of the negative electrode current collector include nickel, copper, and stainless steel.

The negative electrode active material-containing layer contains at least a negative electrode active material. Furthermore, a binder is contained as necessary.

The negative electrode active material may be any material that can occlude and release lithium ions, such as lithium metal, lithium alloy, lithium compound, carbon material, silicon carbide compound, silicon oxide compound, titanium sulfide, boron carbide compound, or silicon. , Tin, or an alloy mainly composed of cobalt.

Examples of carbon materials include non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, activated carbon, carbon blacks, etc. Can be mentioned. Examples of the cokes include pitch coke, needle coke, and petroleum coke. Examples of the fired organic polymer compound include those obtained by firing and carbonizing a phenol resin, a furan resin, or the like at an appropriate temperature.

Other materials that can occlude and release lithium ions at a relatively low potential include, for example, iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, tin oxide, and Li _2.6 Co _0.4 N. Can also be used as the negative electrode active material.
The binder is the same as the binder used in the positive electrode active material-containing layer forming step.

As a method for forming a negative electrode active material-containing layer, a slurry is prepared by mixing a negative electrode active material, a binder, and a solvent, and the prepared slurry is applied onto a negative electrode current collector, followed by drying and then pressing. The method etc. are mentioned.

<Nonaqueous electrolyte application process>
As a nonaqueous electrolyte provision process, what is necessary is just the process of making the said laminate contain a nonaqueous electrolyte, The method of inject | pouring a nonaqueous electrolyte into a laminate, the method of immersing a laminate in a nonaqueous electrolyte, etc. are mentioned.

Examples of the non-aqueous electrolyte include a non-aqueous electrolyte, an inorganic solid electrolyte, and a solid or gel polymer electrolyte in which an electrolyte salt is mixed or dissolved.

Examples of the non-aqueous electrolyte include those prepared by appropriately combining an organic solvent and an electrolyte salt.
Organic solvents include cyclic carbonate, chain carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, diglyme, triglyme, γ-butyrolactone, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, acetate ester, butyrate ester And propionic acid esters. Examples of the cyclic carbonate include propylene carbonate and ethylene carbonate. Examples of the chain carbonate include diethyl carbonate and dimethyl carbonate. Among these, from the viewpoint of voltage stability, cyclic carbonates and chain carbonates are preferable, and propylene carbonate, dimethyl carbonate, and diethyl carbonate are more preferable. These may be used individually by 1 type and may use 2 or more types together.
Examples of the electrolyte salt contained in the non-aqueous electrolyte include LiClO ₄ , LiPF ₆ , LiBF ₄ , CF ₃ SO ₃ Li, LiCl, and LiBr.

Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide.
Examples of the polymer compound used in the solid polymer electrolyte in which the electrolyte salt is mixed or dissolved include polyethylene oxide, polypropylene oxide, polyphosphazene, polyaziridine, polyethylene sulfide, polyvinyl alcohol, polyvinylidene fluoride, polyhexafluoropropylene, And their derivatives, mixtures, and complexes.

Examples of the polymer compound used in the gel polymer electrolyte in which the electrolyte salt is mixed or dissolved include a fluorine polymer compound, polyacrylonitrile, a copolymer of polyacrylonitrile, polyethylene oxide, a copolymer of polyethylene oxide, and the like. Can be mentioned. Examples of the fluorine-based polymer compound include poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene).
The matrix of the gel electrolyte is preferably a fluorine-based polymer compound from the viewpoint of stability against redox reaction.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

<Particle size distribution measurement>
The composite compound or lithium-containing composite oxide is dispersed in water using ultrasonic waves, and measured with a laser diffraction / scattering particle size distribution measurement device (device name: MT-3300EX) manufactured by Nikkiso Co., Ltd., frequency distribution and accumulation A volume distribution curve was obtained. From the obtained cumulative volume distribution curve, D ₁₀ , D ₅₀ , and D ₉₀ were calculated to obtain D ₉₀ / D ₁₀ .

<Specific surface area (SSA)>
The specific surface area (SSA) of the composite compound and the lithium-containing composite oxide was measured using a BET (Brunauer Emmet Teller) method with a specific surface area measuring device (device name: HM model-1208) manufactured by Mountec.

<Tap density>
The tap density of the composite compound and the lithium-containing composite oxide was measured using a tap density measuring device (device name: Tap Denser KYT-4000K) manufactured by Seishin Enterprise Co., Ltd. The positive electrode active material was filled in a 20 mL plastic tapping cell, and the tap density was calculated from the volume after tapping 700 times with a stroke of 20 mm.

<Measurement method of remaining (free) alkali amount>
1 g of lithium-containing composite oxide was weighed into a 30 mL screw tube bottle, 50 g of pure water was added, and the mixture was stirred for 30 minutes with a stirrer and then filtered. Using a Hiranuma automatic titration apparatus (COM-1750, manufactured by Hitachi High-Tech Co., Ltd.), the obtained filtrate was subjected to neutralization titration with 0.02 mol / L hydrochloric acid to an end point of pH 4.0. Then, the residual alkali amount (mol%) in water per 1 mol of Li contained in the positive electrode active material was calculated from the titration amount.

<Average circularity>
The average circularity of the composite compound and the lithium-containing composite oxide was measured using a flow type particle image analyzer (FPIA-3000, manufactured by Malvern).

(Example 1)
<Production of complex compound>
Nickel sulfate (nickel sulfate (II) hexahydrate, manufactured by Wako Pure Chemical Industries, Ltd.), cobalt sulfate (cobalt sulfate (II) heptahydrate, manufactured by Wako Pure Chemical Industries, Ltd.), and manganese sulfate (manganese sulfate (II The solution obtained by dissolving pentahydrate, manufactured by Wako Pure Chemical Industries, Ltd.) in ion-exchanged water is filtered to obtain 2.5 mol / L nickel sulfate, 1.0 mol / L cobalt sulfate and 1.5 mol. An aqueous solution (1) containing / L manganese sulfate was prepared.

Next, 500 g of ion-exchanged water was put into a first reaction tank having a capacity of 1 L, and stirred at 400 rpm while being kept at 60 ° C. while bubbling with nitrogen gas. In this ion-exchanged water, the aqueous solution (1) was continuously supplied at a rate of 1.2 L / hour and a 28% by mass aqueous ammonia solution at a rate of 0.03 L / hour at the same time. The pH in the reaction vessel was maintained at 12.5.

The core particle-containing liquid obtained in the first reaction tank was stored in the second reaction tank (capacity: 2 L) until the volume reached 80% due to overflow from the first reaction tank.

Next, the core particle-containing liquid was stirred at 400 rpm while being kept at 30 ° C. while bubbling with nitrogen gas in the second reaction tank. To this solution, the aqueous solution (1) was continuously added at 1.2 L / hour and a 28% by weight aqueous ammonia solution at 0.03 L / hour at the same time, while the 18 mol / L aqueous sodium hydroxide solution was used. The pH in the second reaction tank was kept at 10. The supernatant liquid was extracted from the reaction liquid by suction filtration through a filter, the amount of liquid in the reaction system was adjusted, and particles were grown at 30 ° C. for 72 hours. Thereafter, the reaction solution was filtered and then washed with water to obtain a composite compound.

Further, the obtained composite compound was dried at 120 ° C. for 12 hours to obtain a composite compound powder.
The composition of the metal component of the obtained composite compound powder was Ni: Co: Mn = 50.2: 20.0: 29.8 (molar ratio).
Table 1 shows the particle size distribution (D ₁₀ , D ₅₀ , D ₉₀ , D ₉₀ / D ₁₀ ), specific surface area, tap density, and average circularity of this composite compound.
FIG. 1 shows the particle size distribution of this composite compound.

<Production of lithium-containing composite oxide>
200.00 g of the composite compound and 83.67 g of lithium carbonate (Li ₂ CO ₃ , manufactured by SQM) having a Li content of 26.96 mol / kg are mixed and fired at 910 ° C. for 8 hours in an air atmosphere. A lithium-containing composite oxide having a composition of Li _1.014 Ni _0.495 Co _0.197 Mn _0.294 O ₂ was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.

Table 2 shows the particle size distribution (D ₁₀ , D ₅₀ , D ₉₀ , D ₉₀ / D ₁₀ ), specific surface area, tap density, and average circularity of the obtained lithium-containing composite oxide powder.

(Example 2)
<Production of lithium-containing composite oxide>
200.00 g of the composite compound obtained in the same manner as in the method described in Example 1, 83.59 g of lithium carbonate (Li ₂ CO ₃ , manufactured by SQM) having a Li content of 26.96 mol / kg, lithium fluoride ( (LiF, manufactured by Wako Pure Chemical Industries, Ltd.) and 0.06 g were mixed, and charged composition Li _1.014 Ni _{0.495 in the same} manner as in Example 1 except that the mixture was baked at 910 ° C. for 8 hours in the air atmosphere. A lithium-containing composite oxide of Co _0.197 Mn _0.294 O _1.999 F _0.001 was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 2.

(Example 3)
<Production of complex compound>
In Example 1, a composite compound was obtained in the same manner as in Example 1 except that the conditions of the particle growth step in the second reaction vessel were changed to 30 hours at 96C.
About the obtained composite compound, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 1.

<Production of lithium-containing composite oxide>
In Example 1, the lithium-containing composite oxidation of Li _1.014 Ni _0.491 Co _0.198 Mn _0.297 O ₂ was performed in the same manner as in Example 1 except that the composite compound obtained above was used. I got a thing. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 2.

Example 4
<Production of complex compound>
In Example 1, a composite compound was obtained in the same manner as in Example 1 except that the conditions of the particle growth step in the second reaction tank were changed to 30 hours at 120 ° C.
About the obtained composite compound, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 1.

<Production of lithium-containing composite oxide>
200 g of the obtained composite compound, 83.92 g of lithium carbonate (Li ₂ CO ₃ , manufactured by SQM) having a Li content of 26.96 mol / kg, and 0.81 g of zirconium oxide (PCS, manufactured by Nippon Electric Works) were mixed. The charged composition Li _1.014 Ni _0.489 Co _0.197 Mn _0.297 Zr _0.003 O ₂ was carried out in the same manner as in Example 1 except that it was fired at 910 ° C. for 8 hours in the air atmosphere. Lithium-containing composite oxide was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 2.

(Example 5)
<Production of complex compound>
In Example 1, the holding temperature of the first reaction vessel was changed to 70 ° C., and the conditions of the particle growth step in the second reaction vessel were changed to 30 hours at 60 ° C., and in the same manner as in Example 1. A composite compound was obtained.
About the obtained composite compound, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 1.

<Production of lithium-containing composite oxide>
In Example 1, the lithium-containing composite oxidation of Li _1.014 Ni _0.493 Co _0.198 Mn _0.295 O ₂ was performed in the same manner as in Example 1 except that the composite compound obtained above was used. I got a thing. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 2.

(Comparative Example 1)
<Production of complex compound>
Nickel sulfate (nickel sulfate (II) hexahydrate, manufactured by Wako Pure Chemical Industries, Ltd.), cobalt sulfate (cobalt sulfate (II) heptahydrate, manufactured by Wako Pure Chemical Industries, Ltd.) and manganese sulfate (manganese sulfate (II)) A solution obtained by dissolving pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in ion-exchanged water is filtered to obtain 2.5 mol / L nickel sulfate, 1.0 mol / L cobalt sulfate and 1.5 mol / An aqueous solution (1) containing L manganese sulfate was prepared.

Next, 500 g of ion-exchanged water was put into the reaction vessel, and stirred at 400 rpm while being kept at 60 ° C. while bubbling with nitrogen gas. In this ion-exchanged water, the aqueous solution (1) was continuously supplied at a rate of 1.2 L / hour and a 28% by mass aqueous ammonia solution at a rate of 0.03 L / hour simultaneously, while 18 mol / L aqueous sodium hydroxide solution was used. The pH in the reaction vessel was maintained at 12.5. The supernatant liquid was removed from the reaction solution by suction filtration through a filter to adjust the amount of liquid in the reaction system, and particles were grown at 60 ° C. for 72 hours. Thereafter, the obtained reaction solution was filtered and then washed with water to obtain a composite compound.

Further, the obtained composite compound was dried at 120 ° C. for 12 hours to obtain composite compound powder.
The composition of the metal component of the obtained composite compound was Ni: Co: Mn = 50.0: 20.1: 29.9 (molar ratio).
The particle size distribution of the composite compound was measured in an aqueous solvent. The results are shown in Table 1.
FIG. 1 shows the particle size distribution of this composite compound.
The tap density, specific surface area, and average circularity of the composite compound were measured. The results are shown in Table 1.

<Production of lithium-containing composite oxide>
200.00 g of the composite compound and 83.67 g of lithium carbonate (Li ₂ CO ₃ , manufactured by SQM) having a Li content of 26.96 mol / kg are mixed, and the mixture is baked at 910 ° C. for 8 hours in an air atmosphere. A lithium-containing composite oxide having a composition of Li _1.014 Ni _0.493 Co _0.198 Mn _0.295 O ₂ was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Table 2.

(Comparative Example 2)
<Production of composite compound and lithium-containing composite oxide>
A composite compound was obtained in the same manner as in Comparative Example 1 except that the reaction conditions in Comparative Example 1 were changed to 72 hours at pH 10.0 and 30 ° C. Furthermore, a lithium-containing composite oxide having a charging composition Li _1.014 Ni _0.493 Co _0.196 Mn _0.297 O ₂ was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained complex compound and lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Tables 1 and 2.

(Comparative Example 3)
<Production of composite compound and lithium-containing composite oxide>
In Comparative Example 1, a composite compound was obtained in the same manner as in Comparative Example 1 except that the conditions of the particle growth process were changed to 30 ° C. for 60 hours. Furthermore, a lithium-containing composite oxide having a charging composition Li _1.014 Ni _0.495 Co _0.197 Mn _0.294 O ₂ was obtained. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained complex compound and lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Tables 1 and 2.

(Comparative Example 4)
<Production of composite compound and lithium-containing composite oxide>
A composite compound was obtained in the same manner as in Comparative Example 1 except that the reaction conditions in Comparative Example 1 were changed to 60 hours at 60 ° C. Furthermore, to obtain a lithium-containing composite oxide of the charge composition _{_{_{_{Li 1.014 Ni 0.496 Co 0.197 Mn 0.293}}}} O 2. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained complex compound and lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Tables 1 and 2.

(Comparative Example 5)
<Production of composite compound and lithium-containing composite oxide>
A composite compound was obtained in the same manner as in Comparative Example 1 except that the reaction conditions in Comparative Example 1 were changed to pH 10.0 and 50 ° C. for 60 hours. Furthermore, to obtain a lithium-containing composite oxide of the charge composition _{_{_{_{Li 1.014 Ni 0.496 Co 0.197 Mn 0.293}}}} O 2. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained complex compound and lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Tables 1 and 2.

(Comparative Example 6)
<Production of composite compound and lithium-containing composite oxide>
A composite compound was obtained in the same manner as in Comparative Example 1, except that the reaction conditions in Comparative Example 1 were changed to 120 hours at pH 12.5 and 60 ° C. Furthermore, to obtain a lithium-containing composite oxide of the charge composition _{_{_{_{Li 1.014 Ni 0.496 Co 0.197 Mn 0.293}}}} O 2. The composition ratio of the obtained lithium-containing composite oxide coincided with the preparation ratio.
About the obtained complex compound and lithium containing complex oxide, it carried out similarly to Example 1, and evaluated various characteristics. The results are shown in Tables 1 and 2.

(Manufacture of positive electrode)
As positive electrode active materials, positive electrode active materials (lithium-containing composite oxides) of Examples 1 to 5 and Comparative Examples 1 to 6, respectively, and acetylene black (conductive material, trade name: Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) And a polyvinylidene fluoride solution (solvent: N-methylpyrrolidone) containing 12.1% by mass of polyvinylidene fluoride (binder, trade name: KFL # 1120, manufactured by Kureha Chemical Industry Co., Ltd.), and N-methylpyrrolidone Addition to make a slurry. The ratio of the positive electrode active material, acetylene black, and polyvinylidene fluoride during mixing was 90/5/5 in mass ratio (positive electrode active material / acetylene black / polyvinylidene fluoride). The slurry was applied to one side of an aluminum foil having an average thickness of 20 μm (positive electrode current collector, trade name: E-FOIL, manufactured by Toyo Aluminum Co., Ltd.) using a doctor blade. It dried at 120 degreeC and produced the positive electrode sheet by performing roll press rolling (0.3t / cm) twice. The positive electrode sheets obtained from the positive electrode active materials of Examples 1 to 5 were respectively positive electrode sheets 1 to 5 and the positive electrode sheets obtained from the positive electrode active materials of Comparative Examples 1 to 6 were respectively positive electrode sheets 6 to 11. And

(Manufacture of batteries)
Using the positive electrode sheets 1 to 11 manufactured as described above as the positive electrode, a stainless steel simple sealed cell type lithium ion secondary battery was assembled in an argon glove box.
Other materials are as follows.
・ Negative electrode: Lithium foil with an average thickness of 500 μm (lithium foil, manufactured by Honjo Chemical Co., Ltd.)
Negative electrode current collector: Stainless steel plate with an average thickness of 1 mm Separator: Porous polypropylene with an average thickness of 25 μm (Celguard # 2500, manufactured by Celgard)
Electrolyte: LiPF ₆ / EC (ethylene carbonate) + DEC (diethyl carbonate) (1: 1) solution (concentration 1 mol / dm ³ ) (volume ratio of EC and DEC containing LiPF ₆ as a solute (EC: DEC = 1: It means the mixed solution of 1).)
Lithium ion secondary batteries using the positive electrode sheets 1 to 11 are referred to as lithium batteries 1 to 11, respectively.

(Battery characteristics evaluation)
The obtained lithium batteries 1 to 11 were evaluated for the following battery characteristics. The results are shown in Table 3. In addition, evaluation was performed at 25 degreeC.

<Initial characteristics>
The following evaluation was performed using the lithium batteries 1 to 11 manufactured above.
That is, it charged to 4.3V with the load current of 192mA per 1g of positive electrode active materials, and discharged to 2.75V with the load current of 32mA per 1g of positive electrode active materials. The discharge capacity at 4.3 V to 2.75 V was used as the initial capacity, and the measurement was performed using a TOSCAT-3000 (manufactured by Toyo System Co., Ltd.).
Further, the initial efficiency was determined by the initial discharge capacity / initial charge capacity.
Moreover, the initial voltage was calculated | required by the first average discharge voltage.
The results are shown in Table 3.

<Rate characteristics>
The following evaluation was performed using the lithium batteries 1 to 11 manufactured above.
That is, it charged to 4.3V with the load current of 192mA per 1g of positive electrode active materials, and discharged to 2.75V with the load current of 32mA per 1g of positive electrode active materials. Then, it charged to 4.3V with the load current of 192mA per 1g of positive electrode active materials, and discharged to 2.75V with the load current (1C rate) of 480mA per 1g of positive electrode active materials. Furthermore, it charged to 4.3V with the load current of 192mA / g positive electrode active material, and discharged to 2.75V with the load current (5C rate) of 800mA / g positive electrode active material. The capacity with respect to the initial capacity at this time was obtained as a rate characteristic. The results are shown in Table 3.

<Electrode density>
The electrode density is measured by punching an electrode coated on an aluminum foil into a disk having a diameter of 1.8 cm, measuring the mass with an electronic balance, and measuring the thickness with a micrometer. Next, an aluminum foil not coated with an electrode is punched out to a diameter of 1.8 cm, and the mass and thickness are similarly measured. The electrode density was calculated by the following formula (2).
(Thickness of coated electrode−thickness of aluminum foil) × 0.9 ² × π (circumferential ratio) / (mass of coated electrode−mass of aluminum foil) Formula (2)

<Cycle characteristics>
The following evaluation was performed using the lithium batteries 1 to 11 manufactured above.
That is, it charged to 4.3V with the load current of 192mA per 1g of positive electrode active materials, and discharged to 2.75V with the load current of 32mA per 1g of positive electrode active materials. Then, it charged to 4.3V with the load current of 192mA per 1g of positive electrode active materials, and discharged to 2.75V with the load current of 480mA per 1g of positive electrode active materials. Furthermore, it charged to 4.3V with the load current of 192mA / g positive electrode active material, and discharged to 2.75V with the load current of 800mA / g positive electrode active material.
Next, a charge / discharge cycle of charging to 4.3 V at a load current of 192 mA per 1 g of the positive electrode active material and discharging to 2.75 V at a load current of 160 mA per 1 g of the positive electrode active material was repeated 50 times. The value obtained by dividing the discharge capacity at the 50th cycle of the 4.3V charge / discharge cycle by the initial capacity of 4.3V is defined as the cycle maintenance ratio.

In Examples 1 to 5, even if the press pressure for forming the positive electrode active material-containing layer is low, a higher electrode density than Comparative Examples 1 to 6 can be obtained, and good initial characteristics, rate characteristics, and cycle characteristics can be obtained. It was.
The initial capacity, initial efficiency, initial voltage, and rate characteristics of Examples 1 to 5 were excellent results together with Comparative Examples 1 to 6.

On the other hand, the cycle characteristics of Examples 1 to 5 were 1.0% or more superior to the cycle characteristics of 93.1% of Comparative Example 5 that showed the best results among the comparative examples.
In this example, since the Li negative electrode used for the negative electrode deteriorates, long-term cycle evaluation cannot be performed, and the number of repetitions of cycle characteristics is 50. However, the cycle characteristics empirically tend to be proportional to the half power of the number of cycles. When the above result is converted into 1,000 cycles, 94.0% in 50 cycles is 73.0%, and 93.0% in 50 cycles is 69.0%. Furthermore, in terms of 5,000 cycles, 94.0% in 50 cycles is 40%, and 93.0% is 30%.
Therefore, it was confirmed that Examples 1 to 5 were very excellent in terms of cycle characteristics as compared with Comparative Examples 1 to 6. In particular, in Example 1, the cycle characteristic was 96.4%, which was a very good result.

The composite compound of the present invention can obtain a high electrode density even when the pressing pressure during production is low, has high safety, is excellent in discharge capacity per unit volume, and rate characteristics, and is very excellent in cycle characteristics. It can be suitably used as a precursor of a lithium-containing composite oxide.
The lithium-containing composite oxide of the present invention can obtain a high electrode density even when the pressing pressure during production is low, has high safety, excellent discharge capacity per unit volume, and rate characteristics, and further has cycle characteristics. Since it is very excellent, it can be suitably used for a lithium ion secondary battery.
It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2013-092486 filed on April 25, 2013 are cited here as disclosure of the specification of the present invention. Incorporated.

Claims

It contains nickel and manganese, and the ratio (D 90 / D 10 ) of volume-based cumulative 90% diameter (D 90 ) and volume-based cumulative 10% diameter (D 10 ) in laser scattering particle size distribution measurement is 2.00 or less. A composite compound having a tap density of 1.9 g / cm 3 or more and an average circularity of 0.960 or more.
The composite compound according to claim 1, which is a hydroxide.
The composite compound according to claim 1 or 2, wherein the volume-based cumulative 50% diameter (D 50 ) is 5.0 to 13.0 µm.
The composite compound according to any one of claims 1 to 3, further comprising cobalt.
The content of nickel in the composite compound is 44 to 68 mol%, the content of manganese is 22 to 44 mol%, and the content of cobalt is 4 to 28 mol% with respect to the total of nickel, manganese and cobalt. The composite compound according to claim 4.
A method for producing the composite compound according to any one of claims 1 to 5,
An aqueous solution containing nickel and manganese and an alkali are continuously added to the first reaction vessel to precipitate the core particles, thereby obtaining a core particle-containing liquid preparation step for obtaining a core particle-containing liquid containing the core particles;
A moving step of continuously transferring a part of the nuclear particle-containing liquid in the first reaction vessel from the first reaction vessel to the second reaction vessel;
Part of the supernatant from the reaction solution obtained while growing the core particles by continuously adding an aqueous solution containing nickel and manganese and an alkali to the second reaction vessel containing the core particle-containing solution. A method of producing a composite compound, comprising: a particle growth step of removing particles.
The method for producing a complex compound according to claim 6, wherein the moving step is a step of transferring the core particle-containing liquid overflowing from the first reaction vessel to the second reaction vessel.
A mixing step of mixing a lithium compound and the composite compound according to any one of claims 1 to 5 to obtain a mixture;
A method for producing a lithium-containing composite oxide, comprising a firing step of firing the mixture.
The method for producing a lithium-containing composite oxide according to claim 8, wherein the lithium-containing composite oxide is a compound represented by the following general formula (1).
Li a Ni x Mn y Co z Me b O c F d ··· formula (1)
However, in the general formula (1), 1.02 ≦ a ≦ 1.12, 0 <x ≦ 1.0, 0 <y ≦ 1.0, 0 ≦ z ≦ 1.0, 0 ≦ b ≦ 0. 3, 0.90 ≦ x + y + z + b ≦ 1.05, 1.9 ≦ c ≦ 2.1, and 0 ≦ d ≦ 0.03, and Me is composed of Mg, Ca, Sr, Ba, Al, and Zr It is at least one selected from the group.
A lithium-containing composite oxide obtained by the method for producing a lithium-containing composite oxide according to claim 8 or 9.
The lithium-containing composite oxide according to claim 10, wherein the tap density is 1.9 g / cm 3 to 3.0 g / cm 3 and the average circularity is 0.950 or more.
A lithium-containing composite oxide according to claim 10 or 11, a coating liquid containing a binder, a conductive material, and a solvent is applied onto a positive electrode current collector, the lithium-containing composite oxide, a binder, A method for producing a positive electrode for a lithium ion secondary battery, comprising forming a positive electrode active material-containing layer containing a conductive material.
The manufacturing method of the positive electrode for lithium ion secondary batteries of Claim 12 including the pressurization process which applies the pressure of 1 t / cm or less to a positive electrode active material content layer.
A positive electrode manufacturing step of manufacturing a positive electrode;
A laminate production step of producing a laminate by laminating the positive electrode, the separator, and the negative electrode;
Including a nonaqueous electrolyte application step of containing a nonaqueous electrolyte in the laminate,
The method for producing a lithium ion secondary battery, wherein the positive electrode preparation step is the method for producing a positive electrode for a lithium ion secondary battery according to claim 12 or 13.