JP2020100542A - Lithium composite metal oxide powder, positive electrode active material for lithium secondary batteries, positive electrode for lithium secondary batteries, and lithium secondary battery - Google Patents

Abstract

To provide a lithium composite metal oxide powder which has high cycle characteristics when used as a positive electrode active material for lithium secondary batteries.SOLUTION: The lithium composite metal oxide powder satisfies the requirements (1) and (2) in the following: (1) the ratio of the half width A of the diffraction peak within the range of 2θ=64.5±1° to the half width B of the diffraction peak within the range of 2θ=44.4±1°, namely, A/B, is from 1.39 to 1.75 inclusive, in powder X-ray diffractometry using a CuKα ray; and (2) the ratio of the volume-based 90% cumulative particle size (D90) to the volume-based 10% cumulative particle size (D10), namely, D90/D10, is 3 or more.SELECTED DRAWING: None

Description

The present invention relates to a lithium composite metal oxide powder, a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery.

The lithium composite metal oxide is used as a positive electrode active material for lithium secondary batteries. Lithium secondary batteries have already been put to practical use not only in small power sources such as mobile phone applications and notebook computer applications, but also in medium or large power sources such as automobile applications and power storage applications.

Various attempts have been made to improve the battery characteristics such as cycle characteristics of lithium secondary batteries. For example, Patent Document 1 describes an active material in which the ratio of the half widths of the (003) plane and the (104) plane in the powder X-ray diffraction diagram is 0.57 or less.

JP, 2013-206552, A

As the application field of lithium secondary batteries advances, the positive electrode active material of lithium secondary batteries is required to have further improved cycle characteristics.
The present invention has been made in view of the above circumstances, and includes a lithium composite metal oxide powder having high cycle characteristics when used as a positive electrode active material for a lithium secondary battery, a positive electrode active material for a lithium secondary battery, and a lithium secondary battery. An object is to provide a positive electrode for a secondary battery and a lithium secondary battery.

That is, the present invention includes the following inventions [1] to [11].
[1] A lithium composite metal oxide powder that satisfies the following requirements (1) and (2).
Requirement (1): in the powder X-ray diffraction measurement using CuKα ray, the full width at half maximum A of the diffraction peak within the range of 2θ=64.5±1° and the diffraction within the range of 2θ=44.4±1° The ratio (A/B) of the half width B of the peak is 1.39 or more and 1.75 or less.
Requirement (2): The ratio (D ₉₀ /D ₁₀ ) of 90% cumulative volume particle size (D ₉₀ ) determined by particle size distribution measurement to 10% cumulative volume particle size (D ₁₀ ) determined by particle size distribution measurement is 3 or more.
[2] The lithium mixed metal oxide powder according to [1], which satisfies the following requirement (1)-1.
Requirement (1)-1: The half width A is 0.200° or more and 0.350° or less.
[3] The lithium mixed metal oxide powder according to [1] or [2], which satisfies the following requirement (3).
Requirement (3): In powder X-ray diffraction measurement using CuKα ray, integrated intensity I ₁ of diffraction peak in the range of 2θ=64.5±1° and diffraction in the range of 2θ=18.5±1° The ratio I ₂ /I _{1 of the} peak integrated intensity I ₂ is 4.0 or more and 6.0 or less.
[4] The lithium mixed metal oxide powder according to any one of [1] to [3], which satisfies the following formula (I).
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(However, −0.1≦x≦0.2, 0≦y≦0.4, 0≦z≦0.4, 0≦w≦0.1, y+z+w<1, and M is Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, Represents one or more elements selected from the group consisting of In and Sn.)
[5] The lithium mixed metal oxide powder according to [4], wherein x in the formula (I) is 0<x≦0.2.
[6] The lithium composite metal oxide powder according to [4] or [5], wherein y+z+w in the formula (I) is 0<y+z+w≦0.3.
[7] The lithium composite metal oxide powder according to any one of [1] to [6], which has a 50% cumulative volume particle size (D ₅₀ ) of 500 nm or more and 9 μm or less obtained from particle size distribution measurement.
[8] A positive electrode active material for a lithium secondary battery, containing the lithium mixed metal oxide powder according to any one of [1] to [7].
[9] A positive electrode for a lithium secondary battery containing the positive electrode active material for a lithium secondary battery according to [8].
[10] A lithium secondary battery having the positive electrode for a lithium secondary battery according to [9].

According to the present invention, a lithium composite metal oxide powder having high cycle characteristics when used as a positive electrode active material for a lithium secondary battery, a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery. Can be provided.

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

<Lithium mixed metal oxide powder>
The lithium mixed metal oxide powder of this embodiment satisfies the following requirements (1) and (2).
Requirement (1): in the powder X-ray diffraction measurement using CuKα ray, the full width at half maximum A of the diffraction peak within the range of 2θ=64.5±1° and the diffraction within the range of 2θ=44.4±1° The ratio (A/B) of the half width B of the peak is 1.39 or more and 1.75 or less.
Requirement (2): 90% cumulative volume particle size _{(D 90)} and 10% cumulative volume particle size _{(D 10)} ratio of _(D 90 _{/ D 10)} is 3 or more.

By using the lithium mixed metal oxide powder of this embodiment, a positive electrode for a lithium battery having high cycle characteristics can be manufactured.
Here, "cycle characteristics" refers to the maintenance ratio of the discharge capacity after repeating the discharge cycle with respect to the initial discharge capacity.

≪Requirement (1)≫
The lithium mixed metal oxide powder of this embodiment satisfies the following requirement (1).
Requirement (1) In powder X-ray diffraction measurement using CuKα ray, the half-value width A of the diffraction peak within the range of 2θ=64.5±1° and the diffraction peak within the range of 2θ=44.4±1° The ratio (A/B) to the full width at half maximum B is 1.39 or more and 1.75 or less.

In the case of the lithium mixed metal oxide belonging to the space group R-3m, the peak existing in the range of the diffraction angle 2θ=64.5±1° is on the (110) plane of the unit lattice, which is the minimum unit in the crystal structure. It is the corresponding peak.
In the case of the lithium mixed metal oxide belonging to the space group R-3m, the peak existing in the range of the diffraction angle 2θ=44.4±1° is on the (104) plane of the unit lattice, which is the minimum unit in the crystal structure. It is the corresponding peak.

The lower limit of the ratio (A/B) is preferably 1.47, more preferably 1.50, and particularly preferably 1.53. The upper limit of the ratio (A/B) is preferably 1.70, more preferably 1.65, particularly preferably 1.60. The upper limit value and the lower limit value can be arbitrarily combined. Examples of combinations include 1.47 or more and 1.70 or less, 1.50 or more and 1.65 or less, and 1.53 or more and 1.60 or less.

A lithium mixed metal oxide satisfying the requirement (1) becomes a lithium mixed metal oxide having a crystallite with high isotropicity. If the crystallite is highly isotropic, the expansion and contraction of the crystallite, which occurs when lithium is desorbed during charging and when lithium is inserted during discharging, can relax between the crystallites. it can. If the crystallite has high anisotropy, the expansion and contraction of the crystallite that occurs during lithium desorption during charging and during lithium insertion during discharging can relax between the crystallites. This is not possible and causes cracks between crystallites during charge and discharge. It is presumed that high cycle characteristics can be achieved because there are few cracks between crystallites that can be the starting point of deterioration during charge and discharge and excellent stability during charge and discharge.

≪Requirement (1)-1≫
The lithium mixed metal oxide powder of the present embodiment preferably further satisfies the following requirement (1)-1.
Requirement (1)-1: In powder X-ray diffraction measurement using CuKα rays, the half-value width A of the diffraction peak in the range of 2θ=64.5±1° is 0.200° or more and 0.350° or less.
The half value width A is more preferably 0.210 or more, and particularly preferably 0.220 or more. The full width at half maximum A is more preferably 0.340 or less, and particularly preferably 0.330 or less. The upper limit value and the lower limit value can be arbitrarily combined. Examples of the combination include 0.210 or more and 0.340 or less, and 0.220 or more and 0.330 or less. When the full width at half maximum A is within the above range, the stability of the crystal structure during charging is excellent, and it is presumed that high cycle characteristics can be achieved.

≪Requirement (2)≫
The lithium mixed metal oxide powder of this embodiment satisfies the following requirement (2).
Requirement (2): 90% cumulative volume particle size _{(D 90)} and 10% cumulative volume particle size _{(D 10)} ratio of _(D 90 _{/ D 10)} is 3 or more.
In the present embodiment, D ₉₀ /D ₁₀ is preferably 8 or more, more preferably 10 or more, particularly preferably 12 or more. The upper limit of D ₉₀ /D ₁₀ is not particularly limited, but examples thereof include 40 or less, 30 or less, and 20 or less.
The upper limit and the lower limit of D ₉₀ /D ₁₀ can be arbitrarily combined. Examples of the combination include 8 or more and 40 or less, 10 or more and 30 or less, and 12 or more and 20 or less.

Cumulative volume particle size is measured by the laser diffraction scattering method.
First, 0.1 g of the lithium mixed metal oxide powder is put into 50 ml of a 0.2 mass% sodium hexametaphosphate aqueous solution to obtain a dispersion liquid in which the powder is dispersed.
Next, the particle size distribution of the obtained dispersion liquid is measured using Microtrac MT3300EXII (laser diffraction scattering particle size distribution measuring device) manufactured by Microtrac Bell KK to obtain a volume-based cumulative particle size distribution curve.
In the obtained cumulative particle size distribution curve, the value of the particle diameter at 10% accumulation from the fine particle side is 10% cumulative volume particle size (D ₁₀ ) (μm), and the value of the particle diameter at 90% accumulation from the fine particle side is 90% cumulative volume particle size (D ₉₀ ) (μm). Further, the value of the particle diameter at the time of 50% accumulation from the fine particle side is the 50% cumulative volume particle size (D ₅₀ ) (μm).

The lithium mixed metal oxide powder satisfying the requirement (2) has a wide particle size distribution. When the particle size distribution is wide, the electrode density can be increased when manufacturing the positive electrode. Specifically, coarse particles enter into large voids formed between particles, and minute particles enter into small spaces. Thereby, since the electrode density can be improved, the charge/discharge capacity per mass of the lithium mixed metal oxide powder is improved.

By satisfying the requirement (1), when the lithium mixed metal oxide powder of the present embodiment having a crystallite with high isotropic property is used, when the lithium battery is charged and discharged, a crack between crystallites becomes a starting point. It is possible to suppress deterioration during charging and discharging. On the other hand, even with a lithium composite metal oxide powder having a high regularity of unit cell connection, interparticle cracking during charging and discharging is likely to occur when a large number of voids exist between particles due to agglomeration of particles or the like. .. In the present embodiment, a positive electrode having a high electrode density can be manufactured by further satisfying the requirement (2), and thus high cycle characteristics can be obtained.

It is preferable that the lithium mixed metal oxide powder of the present embodiment further satisfy the following requirement (3).
Requirement (3): In powder X-ray diffraction measurement using CuKα ray, integrated intensity I ₁ of diffraction peak in the range of 2θ=64.5±1° and diffraction in the range of 2θ=18.5±1° The ratio I ₂ /I _{1 of the} peak integrated intensity I ₂ is 4.0 or more and 6.0 or less.

In the case of the lithium mixed metal oxide belonging to the space group R-3m, the peak existing in the range of the diffraction angle 2θ=18.5±1° is in the (003) plane of the unit lattice, which is the minimum unit in the crystal structure. It is the corresponding peak.

The ratio I ₂ /I ₁ is more preferably 4.3 or more and particularly preferably 4.5 or more. Further, the ratio I ₂ /I ₁ is more preferably 5.5 or less, and particularly preferably 5.0 or less. The upper limit value and the lower limit value can be arbitrarily combined. Examples of the combination include 4.3 to 5.5, and 4.5 to 5.0.
When the ratio I ₂ /I ₁ is within the above range, the ratio of the (110) plane where lithium is desorbed and inserted is large, and lithium can be desorbed and inserted, resulting in excellent cycle characteristics. It can be used as a positive electrode active material for a lithium secondary battery.

<<Compositional Formula (I)>>
The lithium mixed metal oxide powder of the present embodiment is preferably represented by the following composition formula (I).
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(However, −0.1≦x≦0.2, 0≦y≦0.4, 0≦z≦0.4, 0≦w≦0.1, y+z+w<1, and M is Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, Represents one or more elements selected from the group consisting of In and Sn.)

From the viewpoint of obtaining a lithium secondary battery having good cycle characteristics, x in the composition formula (I) is preferably more than 0, more preferably 0.01 or more, and further preferably 0.02 or more. .. Further, from the viewpoint of obtaining a lithium secondary battery having higher initial Coulombic efficiency, x in the composition formula (I) is preferably 0.1 or less, more preferably 0.08 or less, and 0.06. The following is more preferable.
The upper limit value and the lower limit value of x can be arbitrarily combined.
In this embodiment, 0<x≦0.2 is preferable, and 0<x≦0.1 is more preferable.

From the viewpoint of obtaining a lithium secondary battery having a high discharge capacity, in the composition formula (I), 0<y+z+w≦0.5 is preferable, 0<y+z+w≦0.25 is more preferable, and 0< More preferably, y+z+w≦0.2.

Further, from the viewpoint of obtaining a lithium secondary battery having a low internal resistance of the battery, y in the composition formula (I) is preferably 0.005 or more, more preferably 0.01 or more, and 0.05 It is more preferable that the above is satisfied. Further, from the viewpoint of obtaining a lithium secondary battery having high thermal stability, y in the composition formula (I) is more preferably 0.35 or less, and further preferably 0.33 or less.
The upper limit value and the lower limit value of y can be arbitrarily combined.
In this embodiment, it is preferable that 0<y≦0.4.

Further, from the viewpoint of obtaining a lithium secondary battery having high cycle characteristics, z in the composition formula (I) is preferably 0.01 or more, more preferably 0.02 or more, and 0.1 or more. It is more preferable that there is. Further, from the viewpoint of obtaining a lithium secondary battery having high storage stability at high temperatures (for example, in an environment of 60° C.), z in the composition formula (I) is preferably 0.39 or less, and 0.38 or less. It is more preferable, and it is still more preferable that it is 0.35 or less.
The upper limit value and the lower limit value of z can be arbitrarily combined.

From the viewpoint of obtaining a lithium secondary battery having a low internal resistance of the battery, w in the composition formula (I) is preferably more than 0, more preferably 0.0005 or more, and 0.001 or more. Is more preferable. From the viewpoint of obtaining a lithium secondary battery having a large discharge capacity at a high current rate, w in the composition formula (I) is preferably 0.09 or less, more preferably 0.08 or less, and 0 It is more preferably 0.07 or less.
The upper limit value and the lower limit value of w can be arbitrarily combined.

From the viewpoint of obtaining a lithium secondary battery having high cycle characteristics, M in the composition formula (I) is one selected from the group consisting of Mg, Ca, Zr, Al, Ti, Zn, Sr, W, and B. The above metals are preferable, and one or more metals selected from the group consisting of Al, W, B, and Zr are preferable from the viewpoint of obtaining a lithium secondary battery having high thermal stability.

Lithium mixed metal oxide powder of the present embodiment is preferably _{D 50} is 500nm or more 9μm or less, more preferably at least 8μm or less 1 [mu] m, particularly preferably 3μm or more 7μm or less.

(Layered structure)
In the present embodiment, the crystal structure of the lithium mixed metal oxide powder is a layered structure, more preferably a hexagonal crystal structure or a monoclinic crystal structure.

The hexagonal crystal structure has 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 , P6, P6 / m, P6} 3 / m, P622, P6 1 22, P6 5 22, P6 2 22, P6 4 22, P6 3 22, P6mm, P6cc, P6 3 cm, P6 3 mc, P- 6m2, P-6c2, P-62m, P-62c, P6/mmm, P6/mcc, P6 ₃ /mcm, P6 ₃ /mmc belonging to any one space group selected from the group consisting of.

Further, the monoclinic crystal structure has P2, P2 ₁ , C2, Pm, Pc, Cm, Cc, P2/m, P2 ₁ /m, C2/m, P2/c, P2 ₁ /c, C2/ Be assigned to any one space group selected from the group consisting of c.

Among these, in order to obtain 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 structure belonging to C2/m. The structure is particularly preferable.

<Method for producing lithium mixed metal oxide powder>
The method for producing the lithium mixed metal oxide powder of the present embodiment will be described.
The method for producing the lithium mixed metal oxide powder of the present embodiment is preferably a production method including the following (1), (2) and (3) in this order.
(1) Manufacturing process of precursor powder of positive electrode active material for lithium secondary battery.
(2) A mixing step of mixing the precursor powder and a lithium compound to obtain a mixture.
(3) A step of firing the mixture to obtain a lithium mixed metal oxide powder.

[Manufacturing process of precursor powder of positive electrode active material for lithium secondary battery]
First, a nickel-containing composite metal compound containing a metal other than lithium, that is, nickel as an essential metal and an arbitrary metal such as cobalt or manganese is prepared. The nickel-containing composite metal compound that is the precursor may be a nickel-containing composite metal hydroxide or a nickel-containing composite metal oxide.

The precursor can be produced by a commonly known batch coprecipitation method or continuous coprecipitation method. Hereinafter, a method for producing the metal will be described in detail by taking a nickel-containing composite metal hydroxide containing nickel, cobalt, and manganese (hereinafter sometimes referred to as “composite metal hydroxide”) as a metal.

First, is the continuous coprecipitation described in JP 2002-201028, nickel salt solution, cobalt salt solution, by reacting a manganese salt solution and a complexing _{agent, Ni s Co t Mn u (} OH) 2 ( In the formula, a composite metal hydroxide represented by s+t+u=1) is produced.

The nickel salt that is the solute of the nickel salt solution is not particularly limited, but any of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate can be used, for example.
As the cobalt salt which 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 solute of the manganese salt solution, for example, any one of manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate can be used.
More metal salts are used in proportions corresponding to the composition ratio of the _{Ni s Co t Mn u (OH} ) 2. That is, the amount of each metal salt is specified so that the molar ratio of nickel, cobalt, and manganese in the mixed solution containing the metal salt is s:t:u. Also, water is used as a solvent.

The complexing agent is one capable of forming a complex with nickel, cobalt and manganese ions in an aqueous solution, and examples thereof include ammonium ion donors (ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, etc.), hydrazine and ethylenediamine. Mention may be made of tetraacetic acid, nitrilotriacetic acid, uracil diacetic acid and glycine.

At the time of precipitation, in order to adjust the pH value of the aqueous solution, an alkaline aqueous solution (eg sodium hydroxide, potassium hydroxide) is added if necessary.

The reaction tank may have an inert atmosphere. In an inert atmosphere, it is possible to suppress the aggregation of elements that are more easily oxidized than nickel and to obtain a uniform composite metal hydroxide.

Further, the inside of the reaction tank may be in an appropriate atmosphere containing oxygen or in the presence of an oxidizing agent while maintaining an inert atmosphere. This is because the morphology of the composite metal hydroxide can be easily controlled by appropriately oxidizing the transition metal. The oxygen and the oxidant in the oxygen-containing gas need only have sufficient oxygen atoms to oxidize the transition metal. If a large amount of oxygen atoms are not introduced, the inert atmosphere in the reaction tank can be maintained. When controlling the atmosphere in the reaction tank with a gas species, a predetermined gas species may be aerated in the reaction vessel or the reaction solution may be directly bubbled.

After the above reaction, the obtained reaction precipitate is washed and dried to isolate the nickel-containing composite metal hydroxide as the nickel-containing composite metal compound.

For the isolation, a method of dehydrating a slurry containing a reaction precipitate (coprecipitate slurry) by centrifugation or suction filtration is preferably used.

The coprecipitate obtained by the dehydration is preferably washed with a washing liquid containing water or alkali. In the present embodiment, it is preferable to wash with a washing liquid containing alkali, and it is more preferable to wash with a sodium hydroxide solution.

The nickel-containing composite metal hydroxide can be obtained by drying the reaction precipitate after washing. The nickel-containing composite metal oxide may be obtained by performing heat treatment after drying. When preparing a nickel-containing composite metal oxide from a nickel-containing composite metal hydroxide, an oxidization step is carried out by firing at a temperature of 300° C. or higher and 800° C. or lower for 1 hour or longer and 10 hours or shorter. May be.

-Precursor powder crushing step In the present embodiment, there is a step of crushing the manufactured precursor. By crushing the precursor, a lithium mixed metal oxide powder satisfying the above requirements (1) and (2) can be produced.
The crushing step is preferably carried out using an airflow crusher, a collision crusher with a classification mechanism, a pin mill, a ball mill, a jet mill, a counter jet mill, or the like. Among them, crushing with a jet mill or counter jet mill can crush the agglomeration between primary particles.

Taking the pulverization step with a jet mill as an example, the lower limit of the pulverization pressure is preferably 0.2 MPa, more preferably 0.25 MPa, particularly preferably 0.3 MPa. The upper limit of the crushing pressure is preferably 0.7 MPa, more preferably 0.65 MPa, particularly preferably 0.6 MPa.
The upper limit value and the lower limit value can be arbitrarily combined.
Examples of the combination include 0.2 MPa or more and 0.7 MPa or less, 0.25 MPa or more and 0.65 MPa or less, and 0.3 MPa or more and 0.6 MPa or less.

When the crushing pressure is not more than the above upper limit value, it is possible to produce a lithium composite metal oxide powder that satisfies the requirements (1) and (2) while suppressing the destruction of the crystal structure. When the crushing pressure is at least the above lower limit value, it is possible to prevent the uncrushed coarse particles from remaining and to produce a lithium mixed metal oxide powder that satisfies the requirements (1) and (2).

Before and after the pulverization step, powder X-ray diffraction measurement using CuKα ray was performed on the precursor, and the integrated intensity α of the peak existing in the range of diffraction angle 2θ=19.2±1° and 2θ=33.5. The ratio (α/β) of the peak existing in the range of ±1° to the integrated intensity β is obtained.
In the present embodiment, the ratio (α/β) before the crushing process at this time is A, and the ratio (α/β) after the crushing process is B. In the present embodiment, the ratio of A to B (B/A) is preferably more than 1 and 2 or less, more preferably 1.2 or more and 1.8 or less, and 1.4 or more and 1.7 or less. Particularly preferred.

[Mixing process]
This step is a step of mixing a lithium compound and a precursor to obtain a mixture.

-Lithium compound The lithium compound used in the present invention is any one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, lithium oxide, lithium chloride and lithium fluoride, or a mixture of two or more thereof is used. can do. Of these, either one or both of lithium hydroxide and lithium carbonate is preferable.
When the lithium compound contains lithium carbonate as an impurity, the content of lithium carbonate in lithium hydroxide is preferably 5% by mass or less.

A method for mixing the precursor and the lithium compound will be described.
After the precursor is dried, it is mixed with a lithium compound. The drying conditions are not particularly limited, and examples thereof include any of the following drying conditions 1) to 3).
1) Conditions in which the precursor is not oxidized or reduced. Specifically, it is a condition for drying the oxides or the hydroxides.
2) Conditions under which the precursor is oxidized. Specifically, it is a drying condition that oxidizes a hydroxide to an oxide.
3) Conditions under which the precursor is reduced. Specifically, it is a drying condition for reducing the oxide to the hydroxide.

An inert gas such as nitrogen, helium, or argon may be used for the condition that the oxidation/reduction is not performed, and oxygen or air may be used under the condition that the hydroxide is oxidized.
As a condition for reducing the precursor, a reducing agent such as hydrazine and sodium sulfite may be used under an inert gas atmosphere.

After the precursor is dried, classification may be appropriately performed.

The above lithium compound and precursor are mixed in consideration of the composition ratio of the final target product. For example, a lithium salt is mixed so that the ratio of the number of lithium atoms to the number of metal atoms contained in the composite metal oxide or composite metal hydroxide is greater than 1.0. The ratio of the number of lithium atoms to the number of metal atoms is preferably 1.05 or more, more preferably 1.10 or more. The lithium mixed metal oxide is obtained by firing the mixture of the nickel-containing mixed metal hydroxide and the lithium compound in the subsequent firing step.

[Step of firing mixture to obtain lithium mixed metal oxide powder]
In the present embodiment, the mixture of the lithium compound and the precursor is fired in the presence of the inert melting agent.

The reaction of the mixture can be promoted by firing the mixture in the presence of an inert melting agent. The inert melting agent may remain in the lithium mixed metal oxide powder after firing, or may be removed by washing with a washing liquid after firing. In the present embodiment, it is preferable to wash the lithium mixed metal oxide powder after firing with pure water or an alkaline washing solution.

In the present embodiment, the setting of the firing temperature is not particularly limited, but from the viewpoint of increasing the charge capacity, it is preferably 600° C. or higher, and more preferably 650° C. or higher. The firing temperature is not particularly limited, but it is preferably 1100° C. or lower, and preferably 1050° C. or lower in the sense of preventing Li volatilization and obtaining a lithium composite metal oxide having a target composition. Is more preferable.
The above-mentioned upper limit value and lower limit value of the firing temperature can be arbitrarily combined.

The firing time is preferably 3 hours or more and 50 hours or less. If the firing time exceeds 50 hours, volatilization of lithium tends to substantially deteriorate the battery performance. If the firing time is less than 3 hours, the crystal growth is poor and the battery performance tends to be poor. It is also effective to perform calcination before the above calcination. The calcination temperature is preferably in the range of 300°C or higher and 850°C or lower for 1 to 10 hours.
When the total time is 1 hour or more, the crystal growth proceeds favorably and the battery performance can be improved.

In addition, air, dry air, oxygen atmosphere, inert atmosphere and the like are used for firing, depending on the desired composition, and if necessary, a plurality of heating steps are carried out.

The inert melting agent that can be used in this embodiment is not particularly limited as long as it is difficult to react with the mixture during firing. In the present embodiment, a fluoride of one or more elements (hereinafter referred to as “A”) selected from the group consisting of Na, K, Rb, Cs, Ca, Mg, Sr and Ba, and a chloride of A. , A carbonate, A sulfate, A nitrate, A phosphate, A hydroxide, A molybdate and A tungstate. ..

As the fluoride of A, NaF (melting point: 993° C.), KF (melting point: 858° C.), RbF (melting point: 795° C.), CsF (melting point: 682° C.), CaF ₂ (melting point: 1402° C.), MgF ₂ (Melting point: 1263° C.), SrF ₂ (melting point: 1473° C.) and BaF ₂ (melting point: 1355° C.).

As the chloride of A, NaCl (melting point: 801° C.), KCl (melting point: 770° C.), RbCl (melting point: 718° C.), CsCl (melting point: 645° C.), CaCl ₂ (melting point: 782° C.), MgCl ₂ (Melting point: 714° C.), SrCl ₂ (melting point: 857° C.) and BaCl ₂ (melting point: 963° C.).

As the carbonate of A, Na ₂ CO ₃ (melting point: 854° C.), K ₂ CO ₃ (melting point: 899° C.), Rb ₂ CO ₃ (melting point: 837° C.), Cs ₂ CO ₃ (melting point: 793° C.) , CaCO ₃ (melting point: 825° C.), MgCO ₃ (melting point: 990° C.), SrCO ₃ (melting point: 1497° C.) and BaCO ₃ (melting point: 1380° C.).

As the sulfate of A, Na ₂ SO ₄ (melting point: 884° C.), K ₂ SO ₄ (melting point: 1069° C.), Rb ₂ SO ₄ (melting point: 1066° C.), Cs ₂ SO ₄ (melting point: 1005° C.) , CaSO ₄ (melting point: 1460° C.), MgSO ₄ (melting point: 1137° C.), SrSO ₄ (melting point: 1605° C.) and BaSO ₄ (melting point: 1580° C.).

As the nitrate of A, NaNO ₃ (melting point: 310° C.), KNO ₃ (melting point: 337° C.), RbNO ₃ (melting point: 316° C.), CsNO ₃ (melting point: 417° C.), Ca(NO ₃ ) ₂ (melting point) : 561° C.), Mg(NO ₃ ) ₂ , Sr(NO ₃ ) ₂ (melting point: 645° C.) and Ba(NO ₃ ) ₂ (melting point: 596° C.).

Examples of the phosphate of A include Na ₃ PO ₄ , K ₃ PO ₄ (melting point: 1340° C.), Rb ₃ PO ₄ , Cs ₃ PO ₄ , Ca ₃ (PO ₄ ) ₂ , Mg ₃ (PO ₄ ) ₂ ( Melting point: 1184° C.), Sr ₃ (PO ₄ ) ₂ (melting point: 1727° C.) and Ba ₃ (PO ₄ ) ₂ (melting point: 1767° C.).

As the hydroxide of A, NaOH (melting point: 318° C.), KOH (melting point: 360° C.), RbOH (melting point: 301° C.), CsOH (melting point: 272° C.), Ca(OH) ₂ (melting point: 408° C.) ), Mg(OH) ₂ (melting point: 350° C.), Sr(OH) ₂ (melting point: 375° C.) and Ba(OH) ₂ (melting point: 853° C.).

The molybdate of A includes Na ₂ MoO ₄ (melting point: 698° C.), K ₂ MoO ₄ (melting point: 919° C.), Rb ₂ MoO ₄ (melting point: 958° C.), Cs ₂ MoO ₄ (melting point: 956° C.). ), CaMoO ₄ (melting point: 1520° C.), MgMoO ₄ (melting point: 1060° C.), SrMoO ₄ (melting point: 1040° C.) and BaMoO ₄ (melting point: 1460° C.).

Examples of the tungstate of A include Na ₂ WO ₄ (melting point: 687° C.), K ₂ WO ₄ , Rb ₂ WO ₄ , Cs ₂ WO ₄ , CaWO ₄ , MgWO ₄ , SrWO ₄ and BaWO _4. ..

In this embodiment, two or more of these inert melting agents may be used. When two or more kinds are used, the melting point may be lowered. Further, among these inert melting agents, as the inert melting agent for obtaining the lithium mixed metal oxide powder having higher crystallinity, any one of the carbonate and sulfate of A, the chloride of A or the It is preferably a combination. Further, A is preferably either or both of sodium (Na) and potassium (K). That is, among the above, a particularly preferable inert melting agent is selected from the group consisting of NaOH, KOH, NaCl, KCl, Na ₂ CO ₃ , K ₂ CO ₃ , Na ₂ SO ₄ and K ₂ SO _4. More than a seed.

In this embodiment, potassium sulfate or sodium sulfate is preferable as the inert melting agent.

Pure water or an alkaline cleaning liquid can be used for cleaning the inert melting agent remaining in the lithium mixed metal oxide powder after firing.
Examples of the alkaline cleaning liquid include LiOH (lithium hydroxide), NaOH (sodium hydroxide), KOH (potassium hydroxide), Li ₂ CO ₃ (lithium carbonate), Na ₂ CO ₃ (sodium carbonate), K ₂ CO ₃ An aqueous solution of one or more kinds of anhydrides selected from the group consisting of (potassium carbonate) and (NH ₄ ) ₂ CO ₃ (ammonium carbonate) and hydrates thereof can be mentioned. Ammonia can also be used as the alkali.

The temperature of the cleaning liquid used for cleaning is preferably 15°C or lower, more preferably 10°C or lower, and further preferably 8°C or lower. By controlling the temperature of the cleaning liquid to the above range within a range that does not freeze, excessive elution of lithium ions from the crystal structure of the lithium mixed metal oxide powder into the cleaning liquid during cleaning can be suppressed.

In the cleaning step, as a method of bringing the cleaning liquid and the lithium composite metal oxide powder into contact with each other, an aqueous solution of each cleaning liquid is charged with the lithium composite metal oxide powder and stirred, or an aqueous solution of each cleaning liquid is used as shower water. , A method of applying to the lithium composite metal oxide, or after adding the lithium composite metal oxide powder to the aqueous solution of the cleaning liquid and stirring, separate the lithium composite metal oxide powder from the aqueous solution of each cleaning liquid, then, A method in which an aqueous solution of the cleaning liquid is used as shower water and the separated lithium composite metal oxide powder is used.

The lithium mixed metal oxide obtained by firing is appropriately classified after pulverization and is used as a positive electrode active material for a lithium secondary battery applicable to a lithium secondary battery.

<Lithium secondary battery>
Then, while explaining the configuration of the lithium secondary battery, a positive electrode active material for a lithium secondary battery using the lithium composite metal compound produced by the present embodiment, a positive electrode using a positive electrode active material of the lithium secondary battery, A lithium secondary battery having this positive electrode will be described.

An example of the lithium secondary battery of the present embodiment has a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and an electrolytic solution arranged between the positive electrode and the negative electrode.

1A and 1B are schematic diagrams 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. 1A, a pair of separators 1 having a strip shape, a strip positive electrode 2 having a positive electrode lead 21 at one end, and a strip negative electrode 3 having a negative electrode lead 31 at one end are separated into a separator 1, a positive electrode 2, and a separator. 1 and the negative electrode 3 are stacked in this order and wound to form an electrode group 4.

Next, as shown in FIG. 1B, after accommodating the electrode group 4 and an insulator (not shown) in the battery can 5, the can bottom is sealed, the electrode group 4 is impregnated with the electrolytic solution 6, and the positive electrode 2 and the negative electrode 3 are formed. Place the electrolyte between. Further, by sealing the upper portion of the battery can 5 with the top insulator 7 and the sealing body 8, the lithium secondary battery 10 can be manufactured.

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

As the shape of the lithium secondary battery having such an electrode group 4, a shape defined by IEC60086 or JIS C 8500 which is a standard for a battery defined by the International Electrotechnical Commission (IEC) can be adopted. .. For example, a cylindrical shape and a rectangular shape can be mentioned.

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

Hereinafter, each configuration will be described in order.
(Positive electrode)
The positive electrode of the present embodiment can be manufactured by first preparing 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)
A carbon material can be used as the conductive material included in the positive electrode of the present embodiment. Examples of the carbon material include graphite powder, carbon black (for example, acetylene black), and fibrous carbon material. Since carbon black is a fine particle and has a large surface area, it is possible to enhance the conductivity inside the positive electrode and improve the charge and discharge efficiency and the output characteristics by adding a small amount to the positive electrode mixture, but if too much is added, it may be due to the binder. 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 ratio 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, it is possible to reduce this ratio.

(binder)
A thermoplastic resin can be used as the binder included in the positive electrode of the present embodiment.
The thermoplastic resin may be polyvinylidene fluoride (hereinafter, referred to as PVdF).
), polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride copolymer, propylene hexafluoride/vinylidene fluoride copolymer, tetrafluoride Fluorine resins such as ethylene oxide/perfluorovinyl ether copolymers; polyolefin resins such as polyethylene and polypropylene;

You may use these thermoplastic resins in mixture of 2 or more types. By using a fluororesin and a polyolefin resin as a binder, and the ratio of the fluororesin to the entire 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, the positive electrode It is possible to obtain a positive electrode mixture that has high adhesion to the current collector and high binding force inside the positive electrode mixture.

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

Examples of the method of supporting the positive electrode mixture on the positive electrode current collector include a method of press-molding the positive electrode mixture on the positive electrode current collector. Further, the positive electrode mixture is made into a paste by using an organic solvent, and the paste of the obtained positive electrode mixture is applied to at least one surface side of the positive electrode current collector, dried, and pressed to fix the positive electrode current collector to the positive electrode current collector. A mixture may be supported.

When the positive electrode mixture is formed into a paste, organic solvents that can be used 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 the like; amide-based solvents such as dimethylacetamide and N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP);

Examples of the method of applying the paste of the positive electrode mixture 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.

The positive electrode can be manufactured by the method described above.
(Negative electrode)
The negative electrode which the lithium secondary battery of the present embodiment has, as long as it is possible to dope and dedope lithium ions at a lower potential than the positive electrode, a negative electrode mixture containing a negative electrode active material is carried on the negative electrode current collector. And an electrode composed of the negative electrode active material alone.

(Negative electrode active material)
Examples of the negative electrode active material included in the negative electrode include carbon materials, chalcogen compounds (oxides, sulfides, etc.), nitrides, metals or alloys, and materials capable of doping and dedoping with lithium ions at a lower potential than the positive electrode. To be

Examples of the carbon material that can be used as the negative electrode active material include graphite such as natural graphite and artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fiber, and a fired body of an organic polymer compound.

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 titanium oxide represented by a positive real number; V ₂ O ₅ , VO _{2 and} other vanadium oxides represented by the formula VO _x (where x is a positive real number); Fe ₃ O ₄ , Fe ₂ O ₃ , FeO and other oxides represented by the formula FeO _x (where x is a positive real number); SnO ₂ , SnO and other formulas SnO _x (where x is a positive real number) Oxides of tin; oxides of tungsten represented by the 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 complex metal oxide containing vanadium;

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. Vanadium sulfide represented by the formula VS _x (where x is a positive real number) such as VS; and the formula FeS _x (where x is a positive real number) such as Fe ₃ S ₄ , FeS ₂ , and FeS. Molybdenum sulfide represented by the formula MoS _x (where x is a positive real number) such as Mo ₂ S ₃ or MoS ₂ represented by the formula SnS _x (where, SnS ₂ or SnS _x ) x is a positive real number, tin sulfide; WS ₂ or other formula WS _x (where x is a positive real number), tungsten sulfide; Sb ₂ S ₃ or other formula SbS _x (here Where x is a positive real number) and selenium sulfide represented by the formula SeS _x (where x is a positive real number) such as Se ₅ S ₃ , SeS ₂ , SeS; Can be mentioned.

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

These carbon materials, oxides, sulfides, and nitrides may be used alone or in combination of two or more. Further, 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 usable 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, Sn. Other examples include tin alloys such as —Co, Sn—Ni, Sn—Cu, and Sn—La; alloys such as Cu ₂ Sb and La ₃ Ni ₂ Sn ₇ .

These metals and alloys are, for example, processed into a foil shape and then mainly used alone as an electrode.

Among the above negative electrode active materials, the potential of the negative electrode hardly changes during charging from the uncharged state to the fully charged state (potential flatness is good), the average discharge potential is low, and the capacity retention rate after repeated charge and discharge is low. A carbon material containing graphite as a main component, such as natural graphite or artificial graphite, is preferably used because of its high performance (good cycle characteristics). The shape of the carbon material may be, for example, a flaky 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, if necessary. Examples of the binder include thermoplastic resins, and specific examples thereof include PVdF, thermoplastic polyimide, carboxymethyl cellulose, polyethylene and polypropylene.

(Negative electrode current collector)
Examples of the negative electrode current collector included in the negative electrode include a strip-shaped member made of a metal material such as Cu, Ni, and stainless. Among them, it is preferable that Cu is used as a forming material and processed into a thin film because it is difficult to form an alloy with lithium and 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 by pressure molding, forming a paste using a solvent or the like, coating on the negative electrode current collector, drying and pressing A method of pressure bonding may be mentioned.

(Separator)
Examples of the separator included in the lithium secondary battery according to the present embodiment include a polyolefin film such as polyethylene and polypropylene, a fluororesin, a nitrogen-containing aromatic polymer, and the like, a porous film, a nonwoven fabric, a woven fabric, or the like. Can be used. Further, the separator may be formed by using two or more kinds of these materials, or the separator may be formed by laminating these materials.

In the present embodiment, the separator has a gas permeation resistance of not less than 50 seconds/100 cc and not more than 300 seconds/100 cc according to the Gurley method defined in JIS P 8117 in order to allow the electrolyte to permeate well during battery use (during charge/discharge). It is preferably not more than 50 seconds/100 cc and more preferably not more than 200 seconds/100 cc.

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 stack of separators having different porosities.

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

The electrolyte contained in the electrolytic solution 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 ( wherein, BOB is, bis (oxalato) borate LiFSI (wherein FSI is bis(fluorosulphonyl) imide), a lower aliphatic carboxylic acid lithium salt, a lithium salt such as LiAlCl _4, and a mixture of two or more thereof. 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 electrolytic solution include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-dicarbonate. 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, γ-butyrolactone; Nitriles such as acetonitrile and butyronitrile; Amides such as N,N-dimethylformamide, N,N-dimethylacetamide; 3-methyl Carbamates such as -2-oxazolidone; Sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, and 1,3-propanesultone, or those in which a fluoro group is further introduced into these organic solvents (one of the hydrogen atoms contained in the organic solvent The above may be substituted with fluorine atoms).

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 ethers are more preferable. As the mixed solvent of the cyclic carbonate and the non-cyclic carbonate, a mixed solvent containing ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate is preferable. An electrolytic solution using such a mixed solvent has a wide operating temperature range, is not easily deteriorated even when charged and discharged at a high current rate, is not easily deteriorated even when used for a long time, and is a natural graphite as an active material of a negative electrode. However, even if a graphite material such as artificial graphite is used, it has many features that it is hardly decomposed.

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 enhanced. A mixed solvent containing ethers having a fluorine substituent such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether and dimethyl carbonate has a capacity even when charged and discharged at a high current rate. It is more preferable because the maintenance rate is high.

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 polyorganosiloxane chain or a polyoxyalkylene chain can be used. Further, a so-called gel type in which a non-aqueous electrolytic solution is held in a polymer compound can 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, it may be possible to further enhance the safety of the lithium secondary battery.

Further, 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 needed.

Since the positive electrode active material having the above-described structure uses the lithium composite metal compound manufactured according to the present embodiment described above, it is possible to improve the cycle retention rate of the lithium secondary battery using the positive electrode active material. ..

In addition, since the positive electrode having the above-mentioned configuration has the positive electrode active material for a lithium secondary battery having the above-described configuration, the cycle retention rate of the lithium secondary battery can be improved.

Furthermore, since the lithium secondary battery having the above-described configuration has the above-described positive electrode, the lithium secondary battery has a high cycle maintenance rate.

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

<<Measurement of requirement (1)>>
The powder X-ray diffraction measurement was performed using an X-ray diffractometer (Ultima IV manufactured by Rigaku Corporation). Lithium mixed metal compound powder is filled in a dedicated substrate and measured using a Cu-Kα radiation source under the conditions of diffraction angle 2θ=10° to 90°, sampling width 0.02°, scan speed 4°/min. Then, a powder X-ray diffraction pattern was obtained.
Using the integrated powder X-ray analysis software JADE, the full width at half maximum A of the diffraction peak within the range of 2θ=64.5±1° and the diffraction within the range of 2θ=44.4±1° were obtained from the powder X-ray diffraction pattern. The half width B of the peak was calculated. The ratio (A/B) was calculated from the obtained half-width A and half-width B. The half width A measured at this time is shown in Table 1 as requirement (1)-1.

<<Measurement of requirement (2)>>
0.1 g of the lithium mixed metal oxide powder was put into 50 ml of a 0.2 mass% sodium hexametaphosphate aqueous solution to obtain a dispersion liquid in which the powder was dispersed. Next, the particle size distribution of the obtained dispersion liquid was measured using Microtrac MT3300EXII (laser diffraction scattering particle size distribution measuring device) manufactured by Microtrac Bell KK to obtain a volume-based cumulative particle size distribution curve. Then, in the obtained cumulative particle size distribution curve, the value of the particle diameter at the point where the cumulative volume from the fine particle side is 90% is 90% cumulative volume particle size (D ₉₀ )(μm ), the value of the particle diameter at the point where the cumulative volume is 50% is the 50% cumulative volume particle size (D ₅₀ ) (μm), and the value of the particle diameter at the point where the cumulative volume is 10% is the 10% cumulative volume particle size (D). ₁₀ ) (μm).

<<Measurement of requirement (3)>>
The powder X-ray diffraction measurement was performed using an X-ray diffractometer (Ultima IV manufactured by Rigaku Corporation). Lithium mixed metal compound powder is filled in a dedicated substrate and measured using a Cu-Kα radiation source under the conditions of diffraction angle 2θ=10° to 90°, sampling width 0.02°, scan speed 4°/min. Then, a powder X-ray diffraction pattern was obtained.
Using the integrated powder X-ray analysis software JADE, the integrated intensity I _{1 in} the range of 2θ=64.5±1° and the integrated intensity of diffraction peaks in the range of 2θ=18.5±1° from the powder X-ray diffraction pattern. After obtaining I ₂ , the ratio (I ₂ /I ₁ ) between the integrated intensity I ₂ and the integrated intensity B was calculated.

≪Composition analysis≫
The composition analysis of the lithium mixed metal oxide powder produced by the method described below is performed by dissolving each of the obtained powders in hydrochloric acid, and then using an inductively coupled plasma emission spectrometer (SPS3000 manufactured by SII Nano Technology Co., Ltd.). Was performed using.

<Preparation of positive electrode for lithium secondary battery>
A lithium composite metal oxide, a conductive material (acetylene black), and a binder (PVdF) obtained by the manufacturing method described later were mixed with a composition of lithium composite metal oxide:conductive material:binder=92:5:3 (mass ratio). A paste-like positive electrode mixture was prepared by adding and kneading. When preparing the positive electrode mixture, N-methyl-2-pyrrolidone was used as an organic solvent.

The obtained positive electrode mixture was applied to an Al foil having a thickness of 40 μm, which serves as a current collector, and vacuum dried at 150° C. for 8 hours to obtain a positive electrode for a lithium secondary battery. The electrode area of this positive electrode for a lithium secondary battery was 1.65 cm ² .

<Preparation of lithium secondary battery (coin type half cell)>
The following operations were performed in a glove box in an argon atmosphere.
The positive electrode for a lithium secondary battery manufactured in <Preparation of positive electrode for lithium secondary battery> was placed on the lower lid of a coin-type battery R2032 part (manufactured by Hosen Co., Ltd.) with the aluminum foil surface facing downward, and A laminated film separator (a heat resistant porous layer was laminated on a polyethylene porous film (thickness 16 μm)) was placed on the above. 300 μl of the electrolytic solution was injected therein. The electrolytic solution contains 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) at 30:35. : 35 (volume ratio), a mixture of LiPF ₆ dissolved in 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 was placed on the upper side of the laminated film separator, the upper lid was put through the gasket, and the lithium secondary battery (coin type half cell R2032; hereinafter, “half cell”) was crimped by a crimping machine. May be referred to as).

Charge/Discharge Test Using the half cell manufactured by the above method, a charge/discharge test was carried out under the following conditions to calculate the cycle maintenance rate.

・Cycle test conditions (when 1-yz-w≧0.8 in composition formula (I))
Test temperature 25℃
Charge maximum voltage 4.35V, charge current 0.5CA, constant current constant voltage charge Discharge minimum voltage 2.8V, discharge current 1CA, constant current discharge (1-yz-w<0.8 in composition formula (I). in the case of)
Test temperature 25℃
Charge maximum voltage 4.2V, charge current 0.5CA, constant current constant voltage charge Discharge minimum voltage 2.5V, discharge current 1CA, constant current discharge

The discharge capacity at the first cycle was taken as the cycle initial capacity, and the value obtained by dividing the discharge capacity at the 50th cycle by the cycle initial capacity was calculated, and this value was taken as the cycle maintenance rate.

<<Example 1>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) After water was placed in a reaction tank equipped with a stirrer and an overflow pipe, an aqueous sodium hydroxide solution was added and the liquid temperature was kept at 70°C.

A nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, and a manganese sulfate aqueous solution were mixed so that the atomic ratio of nickel atoms, cobalt atoms, and manganese atoms was 88:8:4, to prepare a mixed raw material liquid.

Next, the mixed raw material solution and an ammonium sulfate aqueous solution were continuously added as a complexing agent into the reaction tank while stirring. Aqueous sodium hydroxide solution was added dropwise at appropriate times so that the pH of the solution in the reaction tank was 11.39, nickel cobalt manganese composite metal hydroxide particles were obtained, washed, and then dehydrated, washed, dehydrated, isolated, The hydroxide raw material powder 1 was obtained by drying.

The hydroxide raw material powder 1 thus obtained was crushed using a jet mill at a crushing gas pressure of 0.6 MPa to obtain a precursor 1.

2. Production and Evaluation of Lithium Composite Metal Oxide The precursor 1 obtained and the amount (mol ratio) of Li to the total amount 1 of Ni, Co and Mn contained in the obtained precursor 1 was 1.15. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 760° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, and dried at 150° C. to obtain a powdery lithium composite metal oxide 1.

As a result of composition analysis of the obtained lithium mixed metal oxide 1, in the composition formula (II), x=0.04, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium composite metal oxide 1 and a charge/discharge test was conducted. The cycle retention rate was 82.6%.

<<Example 2>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was pulverized using a jet mill at a pulverization gas pressure of 0.4 MPa to pulverize the precursor. Got 2.

2. Production and Evaluation of Lithium Mixed Metal Oxide The precursor 2 obtained and the amount (molar ratio) of Li to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 2 was 1.15. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 760° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the above powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated and dried at 150° C. to obtain powdery lithium composite metal oxide 2.

As a result of composition analysis of the obtained lithium mixed metal oxide 2, in the composition formula (II), x=0.04, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium composite metal oxide 2 and a charge/discharge test was conducted. As a result, the cycle retention rate was 82.9%.

<<Example 3>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was pulverized with a counter jet mill at a grinding gas pressure of 0.59 MPa, a supply rate of 2 kg/hour, and a classification. The rotation speed was set to 17,000 rpm and the air volume was set to 1.2 m ³ /min, and the mixture was pulverized to obtain a precursor 3.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (Li) (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 3 was 1.26. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 790° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium-shaped composite metal oxide 3 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 3, in the composition formula (II), x=0.05, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium composite metal oxide 3 and a charge/discharge test was conducted. As a result, the cycle retention rate was 81.3%.

<<Example 4>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was pulverized with a counter jet mill at a grinding gas pressure of 0.59 MPa, a supply rate of 2 kg/hour, and a classification. The rotation speed was set to 17,000 rpm and the air volume was set to 1.2 m ³ /min, and the mixture was pulverized to obtain a precursor 4.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (4) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 4 was 1.26. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated at 820° C. for 10 hours in an O ₂ atmosphere and heated, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium composite metal oxide 4 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 4, in the composition formula (II), x=0.03, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium composite metal oxide 4, and a charge/discharge test was performed. As a result, the cycle retention rate was 86.7%.

<<Example 5>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was pulverized with a counter jet mill at a grinding gas pressure of 0.59 MPa, a supply rate of 2 kg/hour, and a classification. The number of revolutions was set to 17,000 rpm and the air volume was set to 1.2 m ³ /min, followed by pulverization to obtain a precursor 5.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (5) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 5 is 1.26. Mix the lithium hydroxide weighed in 1 and the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate that is an inert flux is 0.05 in a mortar. A mixture was obtained.
Next, the obtained mixture was heated at 820° C. for 10 hours in an O ₂ atmosphere and heated, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium-shaped composite metal oxide 5 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 5, in the composition formula (II), x=0.02, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium mixed metal oxide 5 and a charge/discharge test was conducted. As a result, the cycle retention rate was 87.9%.

<<Example 6>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was pulverized with a counter jet mill at a grinding gas pressure of 0.59 MPa, a supply rate of 2 kg/hour, and a classification. The rotation speed was set to 17,000 rpm and the air volume was set to 1.2 m ³ /min, and the mixture was pulverized to obtain a precursor 6.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (6) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 6 was 1.26. In a mortar, and the weighed lithium hydroxide and potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux was 0.02. A mixture was obtained.
Next, the obtained mixture was heated at 820° C. for 10 hours in an atmosphere of O ₂ , and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium-shaped composite metal oxide 6 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 6, in the composition formula (II), x=0.02, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium mixed metal oxide 6 and a charge/discharge test was conducted. As a result, the cycle retention rate was 87.9%.

<<Example 7>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) After water was put in a reaction tank equipped with a stirrer and an overflow pipe, an aqueous sodium hydroxide solution was added and the liquid temperature was kept at 50°C.

A nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, and a manganese sulfate aqueous solution were mixed so that the atomic ratio of nickel atoms, cobalt atoms, and manganese atoms was 91:7:2 to prepare a mixed raw material liquid.

Next, the mixed raw material solution and an ammonium sulfate aqueous solution were continuously added as a complexing agent into the reaction tank while stirring. Aqueous sodium hydroxide solution was added dropwise so that the pH of the solution in the reaction tank would be 12.5 to obtain nickel-cobalt-manganese mixed metal hydroxide particles, which were washed and then dehydrated, washed, dehydrated, isolated, The hydroxide raw material powder 2 was obtained by drying.

The hydroxide raw material powder 2 thus obtained was crushed using a counter jet mill under the conditions of a crushing gas pressure of 0.59 MPa, a supply rate of 2 kg/hour, a classification rotation speed of 17,000 rpm, and an air flow rate of 1.2 m ³ /min. Got 7.

2. Production and Evaluation of Lithium Composite Metal Oxide The precursor 7 obtained and the amount (mol ratio) of Li to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 7 was 1.26. Mix the lithium hydroxide weighed in 1 and the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.10. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 790° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium-shaped composite metal oxide 7 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 7, in the composition formula (II), x=0.03, y=0.07, z=0.02, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium mixed metal oxide 7 and a charge/discharge test was conducted. The cycle retention rate was 84.5%.

<<Example 8>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) Water was placed in a reaction tank equipped with a stirrer and an overflow pipe, and then an aqueous sodium hydroxide solution was added to maintain the liquid temperature at 30°C.

A nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, and a manganese sulfate aqueous solution were mixed so that the atomic ratio of nickel atoms, cobalt atoms, and manganese atoms was 50:20:30 to prepare a mixed raw material liquid.

Next, the mixed raw material solution and an ammonium sulfate aqueous solution were continuously added as a complexing agent into the reaction tank while stirring. An aqueous sodium hydroxide solution was added dropwise at appropriate times so that the pH of the solution in the reaction tank would be 12.1, nickel cobalt manganese composite metal hydroxide particles were obtained, washed, and then dehydrated, washed, dehydrated, isolated, The hydroxide raw material powder 3 was obtained by drying.

The obtained hydroxide raw material powder 3 was pulverized by using a counter jet mill and a jet mill with the pulverization gas pressure set to 0.4 MPa to obtain a precursor 8.

2. Production and Evaluation of Lithium Composite Metal Oxide The precursor 8 obtained and the amount of Li (molar ratio) relative to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 8 was 1.26. Mix the lithium hydroxide weighed in 1 and the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.10. A mixture was obtained.
Then, the obtained mixture was heated in an O ₂ atmosphere at 940° C. for 5 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium complex metal oxide 8 having a shape of a circle was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 8, in the composition formula (II), x=0. 2, y=0.20, z=0.30, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium composite metal oxide 8 and a charge/discharge test was conducted. As a result, the cycle retention rate was 86.3%.

<<Comparative Example 1>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was crushed using a jet mill with the crushing gas pressure set to 0.8 MPa to crush the precursor. Got 9.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (9) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 9 was 1.15. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 760° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the above powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated and dried at 150° C. to obtain a powdery lithium composite metal oxide 9.

As a result of composition analysis of the obtained lithium mixed metal oxide 9, in the composition formula (II), x=0.05, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium composite metal oxide 9 and a charge/discharge test was conducted. As a result, the cycle retention rate was 78.2%.

<<Comparative Example 2>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was used as the precursor 10.

2. Production and Evaluation of Lithium Composite Metal Oxide The precursor 10 obtained and the amount (molar ratio) of Li to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 10 was 1.15. Mix the lithium hydroxide weighed in 1 with the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.1. A mixture was obtained.
Next, the obtained mixture was heated in an O ₂ atmosphere at 760° C. for 10 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated and dried at 150° C. to obtain a powdery lithium composite metal oxide 10.

As a result of composition analysis of the obtained lithium mixed metal oxide 10, in the composition formula (II), x=0.05, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium composite metal oxide 10 and a charge/discharge test was conducted. The cycle retention rate was 72.9%.

<<Comparative Example 3>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) Water was placed in a reaction tank equipped with a stirrer and an overflow pipe, and then an aqueous sodium hydroxide solution was added to maintain the liquid temperature at 30°C.

A nickel sulfate aqueous solution, a cobalt sulfate aqueous solution, and a manganese sulfate aqueous solution were mixed so that the atomic ratio of nickel atoms, cobalt atoms, and manganese atoms was 50:20:30 to prepare a mixed raw material liquid.

Next, the mixed raw material solution and an ammonium sulfate aqueous solution were continuously added as a complexing agent into the reaction tank while stirring. An aqueous sodium hydroxide solution was added dropwise at appropriate times so that the pH of the solution in the reaction tank would be 12.1, nickel cobalt manganese composite metal hydroxide particles were obtained, washed, and then dehydrated, washed, dehydrated, isolated, By drying, hydroxide raw material powder 4 was obtained as precursor 11.

2. Production and Evaluation of Lithium Mixed Metal Oxide The amount of precursor (11) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 11 should be 1.26. Mix the lithium hydroxide weighed in 1 and the potassium sulfate weighed so that the amount (molar ratio) of potassium sulfate to the total amount of lithium hydroxide and potassium sulfate as an inert flux is 0.10. A mixture was obtained.
Then, the obtained mixture was heated in an O ₂ atmosphere at 940° C. for 5 hours, and then cooled to room temperature to obtain a fired product.
The obtained baked product was pulverized, dispersed in pure water at 5° C., and then dehydrated. Further, the powder was washed with pure water adjusted to a liquid temperature of 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. A lithium-shaped composite metal oxide 11 was obtained.

As a result of composition analysis of the obtained lithium mixed metal oxide 11, in the composition formula (II), x=0. 2, y=0.20, z=0.30, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was prepared using the lithium composite metal oxide 11 and a charge/discharge test was conducted. As a result, the cycle retention rate was 71.3%.

<<Comparative Example 4>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 1 obtained in the process of Example 1 was used as the precursor 12.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (12) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 12 should be 1.08. The lithium hydroxide weighed in 1 was mixed with a mortar to obtain a mixture.
Next, the obtained mixture was heated in an O ₂ atmosphere at 820° C. for 6 hours, and then cooled to room temperature, and the obtained fired product was pulverized to obtain a powdery lithium composite metal oxide 12.

As a result of composition analysis of the obtained lithium mixed metal oxide 12, in the composition formula (II), x=0.04, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium composite metal oxide 12, and a charge/discharge test was conducted. As a result, the cycle retention rate was 75.2%.

<<Comparative Example 5>>
1. Production of Lithium Composite Metal Oxide Precursor (Coprecipitate) The hydroxide raw material powder 2 obtained in the process of Example 8 was used as the precursor 13.

2. Production and Evaluation of Lithium Composite Metal Oxide The amount of precursor (13) and the amount of Li (molar ratio) with respect to the total amount 1 of Ni, Co, and Mn contained in the obtained precursor 13 should be 1.10. The lithium hydroxide weighed in 1 was mixed with a mortar to obtain a mixture.
Next, the obtained mixture was heated in an O ₂ atmosphere at 760° C. for 6 hours and then cooled to room temperature to obtain a fired product.
The obtained calcined product was pulverized, dispersed in pure water at 5° C., dehydrated, heated at 80° C. for 15 hours, and then continuously heated at 150° C. for 9 hours to be dried and powdered. Lithium mixed metal oxide 13 was obtained.

As a result of the composition analysis of the obtained lithium mixed metal oxide 13, in the composition formula (II), x=−0.01, y=0.08, z=0.04, and w=0.

3. Charge/Discharge Test of Non-Aqueous Electrolyte Secondary Battery A coin-type battery was produced using the lithium mixed metal oxide 13 and a charge/discharge test was conducted. As a result, the cycle retention rate was 72.5%.

Table 1 shows the powder X-ray diffraction of the precursors obtained in Examples 1 to 8 and Comparative Examples 1 to 5, the crushing conditions and compositions, and the positive electrode active materials obtained in Examples 1 to 8 and Comparative Examples 1 to 5. Ratio (A/B) of half-width A and half-width B obtained from measurement (requirement (1)), ratio of 90% cumulative volume particle size (D ₉₀ ) and 10% cumulative volume particle size (D ₁₀ ) (D ₉₀ /D ₁₀ ) (requirement (2)), full width at half maximum A obtained by powder X-ray diffraction measurement (requirement (1)-1), integrated intensity I ₁ obtained by powder X-ray diffraction measurement, and integrated intensity I ₂ the ratio of _(I 2 _{/ I} 1) (requirement (3)), 50% cumulative volume particle size _{(D 50),} examples 1-8, than the charge-discharge test using the positive electrode active material obtained in Comparative examples 1 to 5 The obtained cycle maintenance rate is shown.

As shown in Table 1, Examples 1 to 7, which are lithium composite metal oxides to which the present invention was applied, had a good cycle retention rate with respect to Comparative Examples 1, 2, 4, and 5. Similarly, Example 8 had a better cycle retention rate than Comparative Example 3.

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

Claims (10)

A lithium composite metal oxide powder satisfying the following requirements (1) and (2).
Requirement (1): in the powder X-ray diffraction measurement using CuKα ray, the full width at half maximum A of the diffraction peak within the range of 2θ=64.5±1° and the diffraction within the range of 2θ=44.4±1° The ratio (A/B) of the half width B of the peak is 1.39 or more and 1.75 or less.
Requirement (2): 90% cumulative volume particle size _{(D 90)} and 10% cumulative volume particle size _{(D 10)} ratio of _(D 90 _{/ D 10)} is 3 or more. The lithium composite metal oxide powder according to claim 1, which satisfies the following requirement (1)-1.
Requirement (1)-1: The half width A is 0.200° or more and 0.350° or less. The lithium composite metal oxide powder according to claim 1, which satisfies the following requirement (3).
Requirement (3): In the powder X-ray diffraction measurement using CuKα ray, the integrated intensity I ₁ of the diffraction peak in the range of 2θ=64.5±1° and the diffraction in the range of 2θ=18.5±1° The ratio I ₂ /I _{1 of the} peak integrated intensity I ₂ is 4.0 or more and 6.0 or less. The lithium mixed metal oxide powder according to any one of claims 1 to 3, which satisfies the following formula (I).
_{Li [Li x (Ni (1} -y-z-w) Co y Mn z M w) 1-x] O 2 ··· (I)
(However, −0.1≦x≦0.2, 0≦y≦0.4, 0≦z≦0.4, 0≦w≦0.1, y+z+w<1, and M is Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, Represents one or more elements selected from the group consisting of In and Sn.) The lithium mixed metal oxide powder according to claim 4, wherein x in the formula (I) is 0<x≦0.2. The lithium composite metal oxide powder according to claim 4 or 5, wherein y+z+w in the formula (I) is 0<y+z+w≦0.3. The lithium composite metal oxide powder according to any one of claims 1 to 6, which has a 50% cumulative volume particle size (D ₅₀ ) of 500 nm or more and 9 μm or less. A positive electrode active material for a lithium secondary battery, comprising the lithium mixed metal oxide powder according to claim 1. A positive electrode for a lithium secondary battery, comprising the positive electrode active material for a lithium secondary battery according to claim 8. A lithium secondary battery having the positive electrode for a lithium secondary battery according to claim 9.

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