JPH101316A - Lithium-cobalt multiple oxide and production thereof, and lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain multiple oxide particle suitable for a positive electrode activating material for Li ion secondary battery by dispersing cobalt hydroxide being trivalent cobalt oxyhydroxide and a specific compound into a lithium hydroxide aqueous liquid and rejecting to heat treatment. SOLUTION: At least one kind between cobalt and cobalt hydroxide oxyhydroxide, each having trivalent valency and a compound at least one kind element among B, Mg, Si, Cu, Cy, Y, Ti, V, Mn, Fe, Ni, Sn, Zr, Sb, Nb, Ru, Pb, Hf, Ta, La, Pr, and Nd are dispersed into the Li hydroxide aqueous liquid and heated to obtain the object complex oxide particles. The Li-Co multiple oxide particle is submicron size and has narrow particle distribution, large specific surface area and a uniform composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to lithium-cobalt composite oxide particles which can be used as a positive electrode material of a lithium-ion secondary battery, a method for producing the same, and a lithium-ion secondary battery using the same.

[0002]

2. Description of the Related Art Lithium-cobalt composite oxides have recently been used as high-power, high-energy-density batteries, for example, as positive electrode active materials used in lithium-ion secondary batteries used in notebook computers, PHS, mobile phones and the like. This is one of the materials that are receiving attention. This material may, for example, "Ultrasonic spray pyrolysis by its application to the synthesis and a lithium secondary battery active material of the spherical LiCoO ₂ fine powder" [Hagiwara, Takashi, Yoshihiko Saito, Teruaki Yanagawa, Nobuo Ogata, Kokichi Yoshida, Takashima Masayuki, Yonezawa Susumu, Mizuno Yasuharu, Nagata Kenji, Ogawa Kenji; Journal of the Ceramic Society of Japan (Journalof the Ceramic So
city of Japan), 101, 1159-
1163 (1993) (hereinafter referred to as “Document 1”)], LiMO ₂ (wherein
M is Cr, Mn, Ni, Fe, Co or V. )
Are particularly suitable as a positive electrode active material because of their high charge / discharge voltage.

When such a lithium-cobalt composite oxide is used as a positive electrode active material of a lithium ion secondary battery, in order to enhance its performance, a composition of the lithium-cobalt composite oxide is changed or a lithium-cobalt composite oxide is used. Improvements in the physical properties of oxides have been proposed. As a composition in which the composition of the lithium-cobalt composite oxide is changed, for example, JP-A-3-127454 discloses a composition in which the composition of the lithium-cobalt composite oxide is made rich in lithium. JP-A-3-1349
No. 69 discloses a composition in which the composition of a lithium-cobalt composite oxide is made rich in cobalt. JP-A-3-201368, JP-A-4-328277, JP-A-4-319250 and JP-A-4-3
No. 19260 discloses a lithium-cobalt composite oxide doped with metal ions such as Mn, W, Ni, La, and Zr.

[0004] Lithium-cobalt composite oxides having improved physical properties are disclosed, for example, in JP-A-4-5606.
Patent Document 4 discloses a lithium cobalt composite oxide having a specific surface area of 2 m ² / g or less. JP-A-4-33260 and JP-A-5-94822 disclose LiCoO ₂ having a certain particle size characteristic. JP-A-3-272564 and JP-A-5-36414 disclose that LiCoO ₂ is a specific X
A crystal particle having a line diffraction intensity is disclosed.

Japanese Patent Application Laid-Open No. 7-263028 discloses that the average particle diameter D is 3 <D ≦ 9.0 μm and the particle diameter is 3 to 150 μm.
A lithium-cobalt composite oxide in which the volume occupied by μm particles is 75% or more of the total volume is disclosed. Japanese Patent Application Laid-Open No. 7-262959 discloses a lithium-cobalt composite oxide having a particle property in which the n value in a rosin-Rammler type particle size distribution (R-λ) is 2.0 or more.

When powder is used as a positive electrode active material of a lithium ion secondary battery, for example, reference 1
As described on page 1159, in order to obtain high reliability and reproducibility with respect to characteristics such as stability to the negative electrode, internal resistance, sensitivity, and response speed during charge and discharge, a submicron size was used. It is necessary to pack a powder having a narrow particle size distribution and a uniform composition at a high density. In particular, in practical batteries,
The volume that can be filled with the powder is constant. Therefore, assuming that there is no difference in battery performance per unit weight of the positive electrode active material, a larger amount of electricity can be extracted as the filling property is higher and the specific surface area of the powder is larger. For this reason, a powder having a high filling property and a large specific surface area has high reliability and reproducibility with respect to various characteristics, and is extremely important in producing a high-output lithium ion secondary battery. is important.

However, any of the above-mentioned lithium cobalt composite oxides includes a lithium source such as lithium carbonate, lithium hydroxide, lithium peroxide, and lithium nitrate;
Since it is synthesized by solid-phase reaction with cobalt sources such as cobalt carbonate, cobalt hydroxide, cobalt oxide, and cobalt nitrate at high temperature, the composition is difficult to be uniform, and the particle size of primary particles increases. However, it was difficult to obtain a material having a large specific surface area. Furthermore, since the primary particles are fused to each other, when used as a positive electrode active material of a secondary battery, it is necessary to perform a pulverizing treatment to obtain a powder having good dispersibility suitable for producing a positive electrode paste. Since such a pulverizing treatment results in a powder having a wide particle size distribution, it has been difficult to narrow the particle size distribution.

[0008]

In view of the above, the present invention has been made in view of the above, and has a submicron size, a narrow particle size distribution, a large specific surface area, and is suitable as a powder for a positive electrode active material for a lithium ion secondary battery. It is an object of the present invention to provide a lithium-cobalt composite oxide particle having a uniform composition, a method for producing the same, and a lithium-ion secondary battery using the same.

[0009]

According to the present invention, there is provided a compound represented by the following general formula (1): LiCo _1-x A _x O _y (1) (where x represents a rational number from 0 to 0.25; y is ,
Represents a rational number from 1.875 to 2.25. A is B, M
g, Si, Cu, Ce, Y, Ti, V, Mn, Fe, N
i, Sn, Zr, Sb, Nb, Ru, Pb, Hf, T
represents at least one element selected from the group consisting of a, La, Pr and Nd. ), And the average value of the major axis of the primary particles is
Lithium-cobalt composite oxide particles having a size of 3.0 μm or less and a crystallite size of 100 to 1000 ° as measured by an X-ray diffraction method. Further, the present invention provides at least one selected from the group consisting of cobalt hydroxide in which the valence of cobalt is trivalent, and cobalt oxyhydroxide.
Species, and B, Mg, Si, Cu, Ce, Y, Ti,
V, Mn, Fe, Ni, Sn, Zr, Sb, Nb, R
The above-described lithium-cobalt composite oxidation, in which a compound comprising at least one element selected from the group consisting of u, Pb, Hf, Ta, La, Pr, and Nd is dispersed in an aqueous lithium hydroxide solution, and then heat-treated. This is a method for producing material particles. Furthermore, the present invention is a lithium ion secondary battery using the above lithium cobalt composite oxide particles as a positive electrode active material. Hereinafter, the present invention will be described in detail.

The lithium-cobalt composite oxide particles of the present invention have the following general formula (1): LiCo _1-x A _x O _y (1) (where x represents a rational number from 0 to 0.25. Is
Represents a rational number from 1.875 to 2.25. A is B, M
g, Si, Cu, Ce, Y, Ti, V, Mn, Fe, N
i, Sn, Zr, Sb, Nb, Ru, Pb, Hf, T
represents at least one element selected from the group consisting of a, La, Pr and Nd. ). X is a rational number from 0 to 0.25. The above y is a rational number of 1.875 to 2.25.

The lithium-cobalt composite oxide particles of the present invention are made of a lithium-cobalt composite oxide having a composition represented by LiCoO ₂ corresponding to x = 0 and y = 2 in the general formula (1). In the general formula (1), 0 <x ≦ 0.25 and 1.87
It may be made of a lithium cobalt composite oxide having a composition corresponding to 5 ≦ y ≦ 2.25.

In the general formula (1), 0 <x ≦ 0.
25 and a lithium-cobalt composite oxide having a composition corresponding to 1.875 ≦ y ≦ 2.25, the lithium-cobalt composite oxide particles of the present invention include:
In addition to Co atom, B, Mg, Si, Cu, Ce, Y, T
i, V, Mn, Fe, Ni, Sn, Zr, Sb, Nb,
It may contain at least one atom selected from the group consisting of Ru, Pb, Hf, Ta, La, Pr and Nd.

0 <x ≦ 0.25 and 1.875
As the lithium cobalt composite oxide having a composition corresponding to ≦ y ≦ 2.25, for example, LiCo _0.9 Ni _0.1
O ₂ , LiCo _0.95 V _0.05 O _2.05 , LiCo _0.98 V _0.02
O _2.02 , LiCo _0.85 Mn _0.15 O ₂ , LiCo _0.95 Mn
_0.05 O ₂ , LiCo _0.97 Ti _0.03 O _2.015 , LiCo
_0.97 Cu _0.03 O _1.985 , LiCo _0.98 Sb _0.02 O _2.02 ,
LiCo _0.90 B _0.10 O ₂ , LiCo _0.95 Mg _0.05 O
_1.975 , LiCo _0.80 Fe _0.20 O ₂ , LiCo _0.99 Ta
_0.01 O _{2.01 and the} like.

The crystal structure of the lithium-cobalt composite oxide is an α-NaFeO ₂ type based on a layered rock salt type, and its X-ray diffraction pattern is shown in ASTM: No. 36-
Similar to 1004 LiCoO ₂ .

In the lithium-cobalt composite oxide particles of the present invention, the average value of the major axis of the primary particles is 3.0 μm or less. If it exceeds 3.0 μm, the particles become large, which is not preferable as a positive electrode active material of a lithium ion secondary battery. Preferably, 0.3-2.
0 μm.

The lithium cobalt composite oxide particles of the present invention have a crystallite size of 1 as measured by an X-ray diffraction method.
00 to 1000 °. The size of the crystallite can be calculated from the following Scherrer's formula based on the measurement by the X-ray diffraction method.

[0017]

(Equation 1)

In the formula, ε represents the size (Å) of a crystallite. λ represents the measured X-ray wavelength (Å). β _1/2 represents a half width (radian). θ represents the Bragg angle (radian) of the diffraction line.

The specific surface area of the lithium-cobalt composite oxide particles of the present invention is preferably from 1 to 50 m ² / g. 1m ² /
If it is less than 0.1 g, the specific surface area is too small, and when used as a positive electrode active material of a lithium ion secondary battery, a large amount of electricity cannot be taken out rapidly. If it exceeds 50 m ² / g, it is stable. Charging / discharging is difficult to obtain.

Since the lithium-cobalt composite oxide particles of the present invention have a primary particle size within the above range, stability, internal resistance, and sensitivity to the negative electrode when used as a positive electrode active material of a lithium ion secondary battery. In addition, high reliability and reproducibility can be obtained for characteristics such as a response speed during charging and discharging. In addition, since the specific surface area can be set in the above range, when used as a positive electrode active material of a lithium ion secondary battery, a large amount of electricity can be stably extracted.

In the present invention, the lithium-cobalt composite oxide particles may include at least one selected from the group consisting of cobalt hydroxide having a cobalt valence of three and cobalt oxyhydroxide; , Mg, S
i, Cu, Ce, Y, Ti, V, Mn, Fe, Ni, S
n, Zr, Sb, Nb, Ru, Pb, Hf, Ta, L
It can be produced by dispersing a compound comprising at least one element selected from the group consisting of a, Pr and Nd in an aqueous solution of lithium hydroxide and then performing a heat treatment.

The cobalt hydroxide used in the present invention has a trivalent cobalt valence and is represented by the following general formula (2): Co (OH) ₃ .aH ₂ O (2) is there. In the formula, a is 0 or more. The cobalt hydroxide is, for example, trivalent cobalt (III)
It can be obtained as a precipitate formed when an alkali is added to an aqueous ammine complex salt solution.

The above-mentioned cobalt oxyhydroxide used in the present invention is not particularly restricted but includes, for example, cobalt nitrate,
Examples thereof include compounds obtained by oxidizing a compound having divalent cobalt such as cobalt chloride or cobalt sulfate with an oxidizing agent and then neutralizing the compound with an alkali.

The oxidizing agent is not particularly restricted but includes, for example, air, oxygen, ozone; permanganate (HMnO ₄ ).
And salts thereof represented by MMnO _{4 and the} like; chromic acid (CrO
₃ ) and M ₂ Cr ₂ O ₇ , M ₂ CrO ₄ , MCrO ₃ C
1, its related compounds represented by CrO ₂ Cl _{2 and the} like;
Halogen such as F ₂ , Cl ₂ , Br ₂ , I ₂ ; H ₂ O ₂ ,
Peroxides such as Na ₂ O ₂ and BaO ₂ ; peroxoic acid and M ₂ S ₂ O ₈ , M ₂ SO ₅ , H ₂ CO ₃ , CH ₃ CO ₃
Salts thereof represented by H or the like; oxygen acids and MCLO, MBr
O, MIO, MCLO ₃ , MBrO ₃ , MIO ₃ , MC
Examples thereof include salts thereof represented by 10 ₄ , MIO ₄ , Na ₃ H ₂ IO ₆ , KIO _{4 and the} like. In the formula, M represents an alkali metal element.

The alkali is not particularly restricted but includes, for example, aqueous solutions of lithium hydroxide, potassium hydroxide, sodium hydroxide, ammonium hydroxide and the like.

The above-mentioned cobalt oxyhydroxide is prepared by dissolving a compound having divalent cobalt such as cobalt nitrate, cobalt chloride, and cobalt sulfate in water to form an aqueous solution, and adding the oxidizing agent and the alkali to form an aqueous solution. It can be obtained by simultaneously performing summation and oxidation. In addition, the above 2
The above-mentioned alkali may be added to an aqueous solution containing a compound having a valent cobalt to synthesize divalent cobalt hydroxide, and then an oxidizing agent may be added to oxidize to obtain the above-mentioned cobalt oxyhydroxide. Further, after adding the oxidizing agent to the aqueous solution containing the compound having divalent cobalt,
The cobalt oxyhydroxide can also be obtained by adding the above alkali and neutralizing it.

In the present invention, at least one selected from the group consisting of cobalt hydroxide and cobalt oxyhydroxide is dispersed in the lithium hydroxide aqueous solution. The aqueous lithium hydroxide solution contains a lithium ion and a hydroxyl ion in the aqueous solution. This can be prepared by dissolving a compound capable of generating lithium ions and hydroxide ions in an aqueous solution, for example, lithium hydroxide, lithium oxide, lithium metal and the like in water. In the present specification, the term “aqueous lithium hydroxide solution” means a solution prepared by dissolving a compound capable of generating lithium ions and hydroxyl ions in water in the above aqueous solution. In the present invention, a compound capable of generating lithium ions and hydroxide ions in the above aqueous solution is used as a lithium source.

The concentration in at least one dispersion selected from the group consisting of the above-mentioned cobalt hydroxide and cobalt oxyhydroxide is not particularly limited, but is usually 0 in terms of the concentration of cobalt atoms. 0.05 to 10 gram atoms / L is preferred. From the viewpoint of operability and economical efficiency in the production process, it is more preferably 0.1 to 5 gram atoms / L.

At least one selected from the group consisting of the above-mentioned cobalt hydroxide and the above-mentioned cobalt oxyhydroxide,
Since the remaining lithium source can be recovered after the reaction, the mixing ratio with the aqueous solution of lithium hydroxide may be (lithium) / (cobalt) ≧ 1 in atomic ratio. From the viewpoint of operability and economical efficiency in the production process, (lithium) / (cobalt) = 1/1 to 50/1, more preferably (lithium) / (cobalt) = 1/1 to 1
20/1, and more preferably (lithium) / (cobalt) = 1/1 to 10/1.

In the production method of the present invention, the charging ratio of at least one selected from the group consisting of the above-mentioned cobalt hydroxide and the above-mentioned cobalt oxyhydroxide to the above-mentioned aqueous lithium hydroxide solution is set to be opposite to the above case. When the atomic ratio is (lithium) / (cobalt) <1, the content of cobalt in the obtained lithium-cobalt composite oxide particles can be made larger than the content of lithium.

In the production method of the present invention, B, Mg, Si, Cu, Ce, Y, Ti,
V, Mn, Fe, Ni, Sn, Zr, Sb, Nb, R
By dispersing a compound consisting of at least one element selected from the group consisting of u, Pb, Hf, Ta, La, Pr and Nd, in the above general formula (1), 0
Lithium-cobalt composite oxide particles having a composition corresponding to <x ≦ 0.25 can be obtained. The compound is not particularly restricted but includes, for example, simple substances, hydroxides and oxides of the above elements. These may be used alone or in combination of two or more. The amount of the compound to be added is such that the atomic ratio in the dispersion is such that the ratio of the atom of the element to the sum of the cobalt atom and the atom of the element in the compound is 0.25 or less. Can be.

In the production method of the present invention, the higher the concentration of hydroxyl ions in the dispersion, the better the reactivity.
Further, a compound capable of generating hydroxyl ions may be added to the dispersion. The compound capable of generating the hydroxyl ion is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

The heating temperature in the heat treatment is 60 to
500 ° C. is preferred. If the temperature is lower than 60 ° C., it takes a long time to complete the reaction. If the temperature is higher than 500 ° C., the steam pressure becomes extremely high, and the pressure resistance of the reaction vessel must be maintained. There is a problem with economy. From the viewpoints of operability and economy in the production process, the temperature is more preferably 100 to 374 ° C. When the heating temperature exceeds 100 ° C., it is necessary to use a pressure-resistant container as a reaction container and to suppress the boiling of the aqueous dispersion.

The reaction time in the above heat treatment varies from several minutes to several days, depending on the heating temperature. The heat treatment may be performed while stirring the dispersion.

In the production method of the present invention, after the heat treatment, the reaction solution is cooled to a temperature at which a separation operation is possible,
The precipitate is separated using a separation method such as filtration, and sufficiently washed with water.
By drying, powder of the target lithium-cobalt composite oxide particles can be obtained. The drying temperature is
There is no particular limitation as long as the adsorbed moisture of the lithium-cobalt composite oxide particles can be sufficiently removed.

If necessary, the product after drying may be subjected to a dry heat treatment. By the dry heat treatment, the crystallinity of the obtained lithium cobalt composite oxide particles can be further increased, and the size of the primary particles can be adjusted. Composite oxide particles can be obtained.
The dry heat treatment may be performed after the lithium-cobalt composite oxide particles obtained after drying are recovered, or may be performed simultaneously with the drying step before recovery.

The liquid phase separated by the above filtration or the like can be recovered and reused. Also, it can be discarded after processing.

According to the production method of the present invention, unlike the solid-state reaction at a high temperature conventionally used for producing lithium-cobalt composite oxide particles, the primary particles do not fuse, and the submicron Lithium-cobalt composite oxide particles having a uniform size can be produced. For this reason, there is no need to perform the conventional pulverization of particles, and lithium cobalt composite oxide particles having a narrow particle size distribution can be obtained.

According to the production method of the present invention, lithium cobalt composite oxide particles having a uniform composition and excellent crystal structure uniformity can be obtained. In this case, the size of the primary particles of the lithium-cobalt composite oxide particles corresponds to the major axis of the crystal, and the average value thereof is 3.0 μm.
It can be: In addition, it is possible to obtain a lithium cobalt composite oxide having a crystallite size of 100 to 1000 ° and a specific surface area of 1 to 50 m ² / g.

The lithium ion secondary battery of the present invention uses the above lithium cobalt composite oxide particles as a positive electrode active material. The positive electrode active material is generally used as a kneaded paste obtained by adding a conductive agent, a binder, a filler, and the like to the lithium cobalt composite oxide particles and kneading the mixture.

The conductive agent is not particularly limited as long as it is an electron conductive material which does not cause a chemical change in a lithium ion secondary battery. Examples of the conductive agent include natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and the like. Examples thereof include carbon fiber, metal powder, metal fiber, and polyphenylene derivative. These may be used alone or in combination of two or more. The amount of the conductive agent to be added is not particularly limited, but is usually preferably 1 to 50% by weight in the kneaded paste. More preferably, 2-
30% by weight.

The binder is not particularly restricted but includes, for example, starch, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, regenerated cellulose, diacetylcellulose polyvinylchloride, polyvinylpyrrolidone, tetrafluoroethylene,
Polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-diene copolymer (EPD
M), sulfonated EPDM, styrene-butadiene rubber, polybutadiene, fluororubber, polyethylene oxide and the like. These may be used alone or in combination of two or more. The amount of the binder added is not particularly limited, but is usually preferably 1 to 50% by weight in the kneaded paste. More preferably, 2-
30% by weight.

The filler is not particularly limited as long as it is a fibrous material which does not cause a chemical change in a lithium ion secondary battery. Examples thereof include olefin polymers such as polypropylene and polyethylene; and fibers such as glass and carbon. be able to. The amount of the filler added is not particularly limited, but is usually 0 to 3 in the kneaded paste.
0% by weight is preferred.

In the lithium ion secondary battery of the present invention, the material of the negative electrode is not particularly limited as long as it is used in ordinary lithium ion secondary batteries. For example, stainless steel, nickel, copper, titanium , Aluminum, calcined carbon and the like.

In the lithium ion secondary battery of the present invention, as a positive electrode active material, the average value of the major axis of the primary particles is 3.0 μm.
In the following, the lithium-cobalt composite oxide particles having a crystallite size of 100 to 1000 °, a specific surface area of 1 to 50 m ² / g and a narrow particle size distribution are used. High reliability and reproducibility can be obtained for characteristics such as performance, internal resistance, sensitivity, and response speed during charging and discharging.

The lithium-ion secondary battery of the present invention can be used, for example, in electronic devices such as notebook computers, mobile phones, cordless handsets, video movies, liquid crystal televisions, electric shavers, portable radios, headphone stereos, backup power supplies, and memory cards. Apparatus: It can be suitably used for medical equipment such as a pacemaker and a hearing aid.

[0047]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Production of lithium cobalt composite oxide particles Examples 1 to 11 and Comparative Example 1 were carried out. The cobalt source and the cobalt-substituted compound shown in Table 1 were dissolved in water, alkali-neutralized, and oxidized to obtain cobalt hydroxide.
The obtained cobalt hydroxide and the lithium source shown in Table 1 were dispersed in water and subjected to a heat treatment to obtain a lithium-cobalt composite oxide. Each cobalt concentration (gram atom /
L), the (lithium) / (cobalt) atomic ratio, the type and amount (g) of the cobalt-substituted compound, the heat treatment temperature and the heat treatment time are shown in Table 1. Table 2 shows the average particle size, specific surface area, and crystallite size of the primary particles of the obtained lithium-cobalt composite oxide particles.

Example 1 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise to 1 L of a 1 mol / L cobalt nitrate solution with stirring to obtain a slurry of cobalt (II) hydroxide precipitate. The slurry was air-oxidized while stirring for 48 hours while blowing air into the slurry, and the obtained slurry was filtered and washed with water to obtain a cake of cobalt (III) oxyhydroxide precipitate. Next, 2.5 mol of lithium hydroxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to this mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 200 ° C. and a heat treatment time of 4 hours. After the reaction was completed, the slurry was filtered, washed with water, dried at 100 ° C., and the obtained powder was measured for X-ray diffraction pattern. As a result, it was confirmed that the powder was lithium cobaltate (LiCoO ₂ ).

Example 2 100 mol of a 1 mol / L cobalt nitrate solution was mixed with 2 mol / L
L of sodium hydroxide aqueous solution (110 ml) was added dropwise with stirring to obtain a slurry of cobalt (II) hydroxide precipitate.
While blowing air into this slurry, air oxidation is performed while stirring for 48 hours, and the obtained slurry is filtered and washed,
A cake of cobalt (III) oxyhydroxide precipitate was obtained.
Next, 4 mol of lithium hydroxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 130 ° C. and a heat treatment time of 24 hours. After the completion of the reaction, the slurry was filtered, washed with water, dried at 100 ° C., and the X-ray diffraction pattern of the obtained powder was measured. As a result, it was confirmed that the powder was lithium cobaltate.

Example 3 2 mol / L of 500 mol of 1 mol / L cobalt nitrate solution
550 ml of L aqueous sodium hydroxide solution was added dropwise with stirring to obtain a slurry of cobalt (II) hydroxide precipitate.
While blowing air into this slurry, air oxidation is performed while stirring for 48 hours, and the obtained slurry is filtered and washed,
A cake of cobalt (III) oxyhydroxide precipitate was obtained.
Next, 2.5 mol of lithium hydroxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and heated at a heat treatment temperature of 250.
The hydrothermal treatment was performed at 2 ° C. for 2 hours. After the reaction,
After the slurry was washed with filtered water and dried at 100 ° C., the X-ray diffraction pattern of the obtained powder was measured, and it was confirmed that the powder was lithium cobalt oxide.

Example 4 A 500 mol of 1 mol / L cobalt chloride solution was added with 2 mol / L
550 ml of L aqueous sodium hydroxide solution was added dropwise with stirring to obtain a slurry of cobalt (II) hydroxide precipitate.
While blowing air into this slurry, air oxidation is performed while stirring for 48 hours, and the obtained slurry is filtered and washed,
A cake of cobalt (III) oxyhydroxide precipitate was obtained.
Next, 10 mol of lithium hydroxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and heated at a temperature of 200 ° C.
Hydrothermal treatment was performed for 8 hours. After the completion of the reaction, the slurry was filtered, washed with water, dried at 100 ° C., and the X-ray diffraction pattern of the obtained powder was measured. As a result, it was confirmed that the powder was lithium cobaltate.

Example 5 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise to 1 L of a 1 mol / L cobalt nitrate solution with stirring to obtain a slurry of cobalt (II) hydroxide precipitate. The slurry was air-oxidized while stirring for 48 hours while blowing air into the slurry, and the obtained slurry was filtered and washed with water to obtain a cake of cobalt (III) oxyhydroxide precipitate. Next, 2.5 mol of lithium hydroxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 300 ° C. and a heat treatment time of 1 hour. After the completion of the reaction, the slurry was filtered, washed with water, dried at 100 ° C., and the X-ray diffraction pattern of the obtained powder was measured. As a result, it was confirmed that the powder was lithium cobaltate.

Example 6 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise to 1 L of a 1 mol / L cobalt sulfate solution with stirring to obtain a slurry of cobalt (II) hydroxide precipitate. The slurry was air-oxidized while stirring for 48 hours while blowing air into the slurry, and the obtained slurry was filtered and washed with water to obtain a cake of cobalt (III) oxyhydroxide precipitate. Next, 2.5 mol of lithium oxide was mixed with the obtained cake of cobalt (III) oxyhydroxide, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 200 ° C. and a heat treatment time of 4 hours. After completion of the reaction, the slurry was washed with filtered water and dried at 100 ° C.
When the line diffraction pattern was measured, it was confirmed to be lithium cobaltate.

Example 7 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise to 1 L of a mixed solution of 0.8 mol / L cobalt nitrate and 0.2 mol / L nickel nitrate while stirring. A slurry of cobalt (II) oxide precipitate was obtained. The slurry was air-oxidized while stirring for 48 hours while blowing air into the slurry, and the obtained slurry was washed with filtered water to obtain a mixed hydroxide precipitate cake. Next, 2 mol of lithium hydroxide was mixed with the obtained hydroxide cake, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 200 ° C. and a heat treatment time of 4 hours. After completion of the reaction, the slurry was washed with filtered water and dried at 100 ° C.
When the X-ray diffraction pattern was measured, it showed a single X-ray diffraction pattern and was confirmed to be lithium cobalt nickelate.

Example 8 A 1% mixed solution of 0.8 mol / L cobalt nitrate and 0.2 mol / L iron nitrate was added to 60 ml of a 30% by weight H ₂ O ₂ solution.
Was added dropwise with stirring to oxidize. To this solution, 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise with stirring, and the resulting slurry was filtered and washed with water to obtain a mixed hydroxide precipitate cake. Next, 2 mol of lithium hydroxide was mixed with the obtained hydroxide cake, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and subjected to hydrothermal treatment at a heat treatment temperature of 200 ° C. and a heat treatment time of 4 hours. After completion of the reaction, the slurry was filtered, washed with water, dried at 100 ° C., and then the X-ray diffraction pattern of the obtained powder was measured. The powder showed a single X-ray diffraction pattern. confirmed.

Example 9 1 mol / L sodium persulfate 6 was added to 1 L of a mixed solution of 0.9 mol / L cobalt nitrate and 0.1 mol / L copper nitrate.
Oxidation was performed by dropping 00 ml while stirring. To this solution, 1.1 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise with stirring, and the resulting slurry was filtered and washed with water to obtain a mixed hydroxide precipitate cake. Next, 2.25 mol of lithium hydroxide was mixed with the obtained hydroxide cake, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and heated at a heat treatment temperature of 20 ° C.
Hydrothermal treatment was performed at 0 ° C. for 4 hours. After completion of the reaction, the slurry was filtered, washed with water and dried at 100 ° C.
When the X-ray diffraction pattern of the obtained powder was measured, it showed a single X-ray diffraction pattern, and it was confirmed that the powder was copper lithium cobaltate.

Example 10 0.95 mol / L of cobalt nitrate and 0.05 mol / L
2.2 L of a 2 mol / L aqueous sodium hydroxide solution was added dropwise to 2 L of a mixed solution of vanadium chloride with stirring to obtain a slurry of cobalt (II) hydroxide precipitate. The slurry was air-oxidized while stirring for 48 hours while blowing air into the slurry, and the obtained slurry was washed with filtered water to obtain a mixed hydroxide precipitate cake. Next, 2.85 mol of lithium hydroxide was mixed with the obtained hydroxide cake, and ion-exchanged water was added to the mixture to make a total amount of 670 ml. This slurry was charged into an autoclave and heated at a heat treatment temperature of 200.
Hydrothermal treatment was performed at 4 ° C. for 4 hours. After the reaction,
After the slurry was washed with filtered water and dried at 100 ° C., an X-ray diffraction pattern of the obtained powder was measured. As a result, the powder showed a single X-ray diffraction pattern and was confirmed to be lithium cobalt vanadate.

Measurement of Average Particle Size Scanning electron microscope (JSM-840F, manufactured by JEOL Ltd.)
An arbitrary 200 primary particles were selected from an electron micrograph taken using the above method, and the weighted average of the major diameter was defined as the average particle size. Specific surface area measurement Surface area measurement device (Monosorb, Quantach)
Rome).

Measurement of crystallite size The obtained lithium-cobalt composite oxide particles were subjected to X-ray diffraction, and the measured X-ray wavelength λ (Å), half width β _1/2 (radian), and the Bragg From the angle θ (radian), the crystallite size ε (Å) was calculated by the following equation.

[0061]

(Equation 2)

[0062]

[Table 1]

Example 11 The lithium cobalt composite oxide particles obtained in Example 1 were further subjected to dry heat treatment at 500 ° C. for 2 hours to obtain lithium cobalt composite oxide particles. The average particle size, specific surface area, and crystallite size of the primary particles of the obtained lithium cobalt composite oxide particles are shown in Table 2.

Comparative Example 1 Lithium carbonate was used as a lithium source, and cobalt oxide was used as a cobalt source. The mixture was calcined at 900 ° C., and a solid phase reaction was performed to obtain lithium-cobalt composite oxide particles. The average particle size, specific surface area, and crystallite size of the primary particles of the obtained lithium cobalt composite oxide particles are shown in Table 2.

[0065]

[Table 2]

An electron micrograph of the lithium-cobalt composite oxide particles obtained in Example 1 is shown in FIG. Further, X of the lithium-cobalt composite oxide particles obtained in Example 1 was
The line diffraction chart is shown in FIG.

Manufacturing Example 12 of Lithium Ion Secondary Battery The lithium cobalt composite oxide, acetylene black and Teflon obtained in Example 1 were combined with 87: 6.5:
Knead well at a weight ratio of 6.5, apply evenly to a clean stainless steel mesh (20 mmφ), and then 200 kg
/ Cm ² and then dried under reduced pressure at 150 ° C. for about 17 hours to produce a positive electrode. A metal lithium foil (20 mmφ, 0.2 mm thickness) was used as a negative electrode, and a nonwoven fabric and a polypropylene microfilm were used as a separator. The electrolyte was prepared by mixing a 1M LiClO ₄ propylene carbonate solution with 1,2-dimethoxyethane (1: 1) to reduce the water content to 20 ppm or less.
The separator was impregnated and used. These components were incorporated into the battery shown in FIG.

Using the battery produced by the above method,
At a constant current of 1.0 mA / cm ² , the battery voltage is 4.2 to
Charge and discharge were repeated between 2.0V. As a result, it was found that the initial capacity was 155 mAh / g, and the discharge capacity at the 50th cycle maintained 89% of the capacity at the first cycle.

[0069]

As described above, the present invention has a submicron size, a narrow particle size distribution, a large specific surface area, a uniform composition, and is suitable for use as a positive electrode active material of a lithium ion secondary battery. The lithium cobalt composite oxide particles that can be obtained can be obtained efficiently.
In addition, a lithium ion secondary battery using the lithium cobalt composite oxide particles as a positive electrode active material has a high charge / discharge voltage, can extract a large amount of electricity, and is suitably used for electronic devices, medical devices, and the like. be able to.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of lithium cobalt composite oxide particles of Example 1.

FIG. 2 is an X-ray diffraction chart of lithium cobalt composite oxide particles of Example 1. The vertical axis is X-ray intensity (cps)
And the horizontal axis is the diffraction angle (2θ).

FIG. 3 is a sectional view illustrating a configuration of a lithium ion secondary battery of Example 12.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead wire 2 Positive electrode collector mesh 3 Positive electrode 4 Separator 5 Negative electrode 6 Negative electrode collector mesh

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H01M 4/58 H01M 4/58 10/40 10/40 Z

Claims (7)

[Claims] The following general formula (1): LiCo _1-x A _x O _y (1) (where x represents a rational number from 0 to 0.25; y is
Represents a rational number from 1.875 to 2.25. A is B, M
g, Si, Cu, Ce, Y, Ti, V, Mn, Fe, N
i, Sn, Zr, Sb, Nb, Ru, Pb, Hf, T
represents at least one element selected from the group consisting of a, La, Pr and Nd. ), And the average value of the major axis of the primary particles is
Lithium-cobalt composite oxide particles having a size of not more than 3.0 μm and a crystallite size of 100 to 1000 ° as measured by an X-ray diffraction method. 2. The lithium-cobalt composite oxide particles according to claim 1, having a specific surface area of 1 to 50 m ² / g. 3. At least one selected from the group consisting of cobalt hydroxide having cobalt valence of 3 and cobalt oxyhydroxide, and B, Mg, Si, C
u, Ce, Y, Ti, V, Mn, Fe, Ni, Sn, Z
r, Sb, Nb, Ru, Pb, Hf, Ta, La, Pr
A method for producing lithium-cobalt composite oxide particles, comprising dispersing a compound comprising at least one element selected from the group consisting of Nd and Nd in a lithium hydroxide aqueous solution and then performing a heat treatment. 4. The concentration of at least one selected from the group consisting of cobalt hydroxide having a valence of cobalt of 3 and cobalt oxyhydroxide is 0.05 to 0.05 in terms of the concentration of cobalt atoms. The method for producing lithium cobalt composite oxide particles according to claim 3, wherein the amount is 10 g atoms / L. 5. An aqueous lithium hydroxide solution comprising at least one selected from the group consisting of cobalt hydroxide having a valence of cobalt of 3 and cobalt oxyhydroxide, and an aqueous solution of lithium hydroxide in an atomic ratio of (lithium) / (Cobalt) = 1/1 to 5
The method for producing lithium-cobalt composite oxide particles according to claim 3, which is charged at a ratio of 0/1. 6. The method for producing lithium-cobalt composite oxide particles according to claim 3, wherein the temperature of the heat treatment is 100 to 374 ° C. 7. A lithium ion secondary battery using the lithium cobalt composite oxide particles according to claim 1 or 2 as a positive electrode active material.