JPH0959026A - Production of lithium nickelate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain lithium nickelate practicable as an anodic agent for lithium ion cells by a single baking process. SOLUTION: Basic nickel carbonate powder is intimately mixed with a water- soluble lithium compound powder at the virtual molar ratio Ni/Li of (1:1), and the mixture is preliminarily baked in the presence of an inert gas or an oxygen- contg. gas at 250-550 deg.C to virtually terminate the generation of carbon dioxide followed by conducting the final baking in the presence of an oxygen gas or oxygen-enriched air at 700-900 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing lithium nickelate.

[0002]

2. Description of the Related Art Lithium-ion batteries have higher volume energy density and mass energy density than nickel-cadmium batteries and nickel-metal hydride batteries.
It is expected to develop as a power source for portable devices such as laptop computers. Lithium cobalt oxide (LiCoO ₂ ) is widely used as a positive electrode agent for lithium ion batteries, but since it is expensive, an inexpensive positive electrode agent to replace it is desired, and lithium nickel oxide (LiNiO ₂ ) is the most suitable. Listed as a strong candidate. Although there is a report that lithium nickelate is obtained by dry-mixing / crushing nickel oxide or nickel hydroxide and lithium carbonate or lithium hydroxide and firing as powder or firing after molding, lithium nickelate is used once. Since the crystals do not grow sufficiently, it is necessary to repeat grinding / mixing / firing several times. At the 33rd Battery Symposium (September 16-18, 1992: Tokyo), Dowa Mining Co., Ltd. disclosed a method for producing lithium cobalt oxide from basic cobalt carbonate and lithium carbonate and its characteristics. Although it has been announced, it is wet-mixed in the presence of organic substances, then dried, first baked at 600 ° C, and then secondly baked (750-900 ° C) after crushing. Basic cobalt carbonate is converted to basic nickel carbonate. Even if it is reread, it is not an inexpensive manufacturing method if it is mixed in the presence of an organic substance and the firing is repeated twice.

A method based on X-ray diffraction measurement is known as a measure of the crystal growth degree of lithium nickelate. This is a method of performing X-ray diffraction measurement of a sample and comparing the peak intensity at a specific wavelength with the peak intensity at another specific wavelength. For example, using Kα ray of copper target, 1 in 2θ
This is a method indicated by a peak degree ratio (003) / (104) of 8.7 ° (003) and 44.3 ° (104). The larger the strength ratio, the more the crystal growth of lithium nickelate is progressing. It is said that lithium nickelate, which is practical as a positive electrode material for lithium-ion batteries, needs to have the strength ratio of 1 or more.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method capable of producing lithium nickelate, which is practical as a positive electrode material for a lithium ion battery, by a single firing.

[0005]

The method for producing lithium nickel oxide according to the present invention comprises a powder of basic nickel carbonate and a powder of a water-soluble lithium compound at a ratio of Ni and Li of substantially 1: 1 mol. After intimately mixing and precalcining in the presence of an inert gas or an oxygen-containing gas at a temperature in the range of 250 to 550 ° C. to substantially end the generation of carbon dioxide gas, then continue to oxygen gas or oxygen-enriched air. 70 in the presence of
The final firing is performed at a temperature in the range of 0 to 900 ° C.

The gist of the present invention is to use basic nickel carbonate as a nickel source, to carry out firing in two stages having different temperature ranges, and to carry out final firing in the presence of oxygen gas or oxygen-enriched air. That is. Although basic nickel carbonate is a porous substance, it starts to decompose at about 200 ° C, and when it exceeds 300 ° C, the decomposition becomes vigorous.
Then the disassembly is completed. The melting point of decomposed NiO is 1950.
° C. Ni ₃ (OH) ₄ CO ₃ → 3NiO + 2H ₂ O + CO ₂ (1) On the other hand, lithium carbonate is stable even at 600 ° C. and melts (melting point 618 ° C.) while decomposing at higher temperatures. The melting point of decomposed lithium oxide is 1700 ° C. or higher. Li ₂ CO ₃ → Li ₂ O + CO ₂ (2) Therefore, when the mixture of the basic nickel carbonate powder and the water-soluble lithium compound powder is first heated to 250 to 550 ° C., preferably 300 to 500 ° C., the basic nickel carbonate is The decomposition of carbon dioxide only proceeds, and carbon dioxide gas in the crystal structure is released. After the generation of carbon dioxide gas is substantially terminated, that is, after the basic nickel carbonate has become nickel oxide having many fine pores, when the temperature is further increased, the molten lithium carbonate and the decomposed lithium oxide become nickel oxide. It is presumed that it will penetrate into the micropores of and will be in an extremely close contact state. Here, in the presence of oxygen gas or oxygen-enriched air, 70
When fired at a temperature of 0 to 900 ° C., Ni changes from divalent to trivalent and lithium nickel oxide is produced. The estimated reaction formula is as follows. 4Ni ₃ (OH) ₄ CO ₃ → 12NiO + 8H ₂ O + 4CO ₂ (1 ′) 12NiO + 6Li ₂ CO ₃ + 3O ₂ → 12LiNiO ₂ + 6CO ₂ (3)

The lower limit of the final calcination temperature is 700 ° C. because the crystal growth of lithium nickelate is slow at a temperature lower than this and a calcination time longer than industrially allowable is required. The reason why the upper limit of the final firing temperature is 900 ° C. is that the vaporization of lithium is likely to occur at a temperature higher than this. Since the ratio of Ni to Li in the target lithium nickelate is 1: 1 mol, Ni and L
It is natural to mix the powder of the basic nickel carbonate and the powder of the water-soluble lithium compound in a ratio that i is substantially 1: 1 mol, but in consideration of the volatilization of lithium in the final firing step, the lithium The molar ratio may be slightly increased.
During the pre-baking period of 250 to 550 ° C., the purpose is to decompose basic nickel carbonate and release carbon dioxide gas, so that an inert gas or an oxygen-containing gas may be flowed, but 700 to
Since calcination at 900 ° C. requires Ni to be trivalent to trivalent, it needs to be carried out in the presence of oxygen gas or oxygen-enriched air. The oxygen-enriched air preferably has an oxygen content of 50% or more. As seen in Comparative Examples described later, it is difficult to obtain a product having the above-mentioned intensity ratio of 1 or more by X-ray diffraction measurement by firing in the presence of air.

The basic nickel carbonate is obtained by reacting a water-soluble nickel compound with a compound selected from the group consisting of alkali carbonate, alkali bicarbonate, ammonium carbonate and ammonium bicarbonate in water, and filtering and drying a precipitate. Is obtained by The basic nickel carbonate can be obtained by reacting a mixture of a water-soluble nickel compound, a compound selected from the group consisting of alkali carbonate, alkali bicarbonate, ammonium carbonate and ammonium bicarbonate and sodium hydroxide in water. Filter the precipitate,
It can also be obtained by drying. By changing the ratio of sodium hydroxide, the ratio of hydroxyl groups and carbonate groups of basic nickel carbonate can be changed. Examples of the water-soluble nickel compound include nickel nitrate, nickel sulfate, nickel chloride and the like. To precipitate the basic nickel carbonate, there is a slight excess of carbonate radical, that is, C per 1 mol of Ni.
It is preferable to use the carbonate or bicarbonate in a ratio of O ₃ root of about 1.2 mol or more. It is considered that basic nickel carbonate having a larger specific surface area is more preferable.

As the water-soluble lithium compound, lithium hydroxide can be used in addition to lithium carbonate.

The powder obtained by intimately mixing the powder of basic nickel carbonate and the powder of the water-soluble lithium compound remains as powder.
The firing may be performed in two steps (preliminary firing at a temperature of 250 to 550 ° C. and final firing at a temperature of 700 to 900 ° C.), or two-step firing may be performed in the state where the mixed powder is formed into a molded product. good. In the case of forming a molded product, it is desirable that at least one of the length, the width and the thickness is 2 mm or less so that the emission of carbon dioxide gas and the invasion of oxygen are not significantly hindered.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The raw materials used in Examples and Comparative Examples are shown in Table 1.

[0012]

[Table 1]

[0013]

[Basic Nickel Carbonate Preparation Example 1] Nickel nitrate 581.
4 g (2 mol) was dissolved in water to give a 2 L nickel nitrate aqueous solution. 254.4 g (2.4 mol; sodium carbonate)
Ni: CO ₃ molar ratio = 1: 1.2) was dissolved in water to obtain 1.8
L aqueous solution of sodium carbonate was used. 80 liters of the nickel nitrate aqueous solution and the sodium carbonate aqueous solution are added to 1 L of hot water at 70 ° C.
The mixture was added at a constant rate and reacted at the same time over a period of minutes. At this time, the temperature was maintained at 70 ° C. and a good stirring state was maintained. After the completion of pouring, this state was maintained for 30 minutes for aging.
The precipitate thus obtained is filtered, washed with water and then at 120 ° C.
For 16 hours. The basic nickel carbonate powder thus obtained had a nickel content of 53.7% and a specific surface area of 250 m ² / g according to the BET method.

[0014]

Example 1 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
0.0 g of lithium carbonate and 17.1 g of lithium carbonate (Ni: Li molar ratio = 1: 1) were well pulverized and mixed in a mortar. This was heated to 400 ° C. under the flow of air, and maintained at this temperature for about 2 hours until the generation of carbon dioxide gas was not observed, and pre-baking was performed. After that, the flow was switched to oxygen flow and final firing was performed at 800 ° C. for 18 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 24 hours in total. The X-ray diffraction measurement of the obtained sample was performed by the powder measurement method using the Kα ray of the copper target. 1 in 2θ
The peak intensity ratio (003) / (104) of 8.7 ° (003) and 44.3 ° (104) is 1.45, which is 1 or more, which is said to be practical as a positive electrode agent for lithium ion batteries. Met.

[0015]

Example 2 The same operation as in Example 1 was performed, except that after pre-baking at 400 ° C., the flow of oxygen was changed to final baking at 850 ° C. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.47.

[0016]

[Comparative Example 1] 80 after pre-baking at 400 ° C with air flowing
The same operation as in Example 1 was performed except that the final firing was performed at 0 ° C. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.81. No improvement in the peak intensity ratio was observed even if the firing time at 800 ° C. was extended.

[0017]

[Comparative Example 2] 85 after pre-baking at 400 ° C with air flowing
The same operation as in Example 1 was performed except that the final firing was performed at 0 ° C. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.91. No improvement in peak intensity ratio was observed even if the firing time at 850 ° C. was extended.

The results of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are summarized in Table 2. It can be seen that the final firing needs to be performed in the presence of oxygen gas or oxygen-enriched air in order to obtain lithium nickel oxide having a peak intensity ratio of 1.0 or more by X-ray diffraction measurement.

[0019]

[Table 2]

[0020]

Example 3 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. Further, after kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm.
After drying at 16 ° C. for 16 hours, the temperature was raised to 400 ° C. under the flow of air, and the temperature was maintained at this temperature for about 2 hours until the generation of carbon dioxide gas was not observed, and pre-baking was performed. After that, the flow was switched to oxygen flow and final firing was performed at 800 ° C. for 18 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 24 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.43.

[0021]

Example 4 The same operation as in Example 3 was carried out except that after pre-baking at 400 ° C., the flow of oxygen was changed to final baking at 850 ° C. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.43.

[0022]

Comparative Example 3 The same operation as in Example 3 was carried out except that after pre-baking at 400 ° C., final baking was carried out at 800 ° C. with air flowing. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.85. No improvement in the peak intensity ratio was observed even if the firing time at 800 ° C. was extended.

[0023]

[Comparative Example 4] The same operation as in Example 3 was carried out except that after pre-baking at 400 ° C, final baking was carried out at 850 ° C with air flowing. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.91. No improvement in peak intensity ratio was observed even if the firing time at 850 ° C. was extended.

The results of Example 3, Example 4, Comparative Example 3 and Comparative Example 4 are summarized in Table 3. Firing the powder of intimately mixing the powder of basic nickel carbonate and the powder of water-soluble lithium compound into a molded product (pre-baking and final baking)
It is understood that the final calcination still needs to be performed in the presence of oxygen gas or oxygen-enriched air in order to obtain lithium nickel oxide having a peak intensity ratio of 1.0 or more by X-ray diffraction measurement.

[0025]

[Table 3]

[0026]

Example 5 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. After further kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm, and 120 ° C.
After being dried for 16 hours, the temperature was raised to 400 ° C. under the flow of air, and the temperature was maintained at this temperature for about 2 hours until the generation of carbon dioxide was not observed, and pre-baking was performed. After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.16. When compared with Example 3 (molding 0.8 mm product firing), even if the final firing time is 1/3 (total heat treatment time is 1/2), it is a peak that is practical as a positive electrode agent for lithium ion batteries. It was possible to manufacture lithium nickel oxide having a strength ratio of 1 or more by a single firing.

[0027]

Example 6 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. After further kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm, and 120 ° C.
After drying for 16 hours, the temperature was raised to 300 ° C. under the flow of air, and the temperature was maintained at this temperature for about 2 hours until the generation of carbon dioxide gas was not observed, and pre-baking was performed. After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.37.

[0028]

Example 7 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. After further kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm, and 120 ° C.
After being dried for 16 hours, the temperature was raised to 500 ° C. under the flow of air, and the temperature was maintained at this temperature for about 2 hours until the generation of carbon dioxide was not observed, and pre-baking was performed. After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.19.

[0029]

Comparative Example 5 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. After further kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm, and 120 ° C.
After drying for 16 hours, the temperature was raised to 200 ° C. under the flow of air, and the temperature was maintained at this temperature for about 2 hours until the generation of carbon dioxide was not observed, and pre-baking was performed. After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio by X-ray diffraction measurement of the obtained sample was 0.95.

The results of Example 5, Example 6, Example 7 and Comparative Example 4 are summarized in Table 4. Pre-baking temperature is 250
It can be seen that it is suitable to carry out in the range of ~ 550 ° C, preferably 300-500 ° C.

[0031]

[Table 4]

[0032]

Example 8 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
0.0 g of lithium carbonate and 17.1 g of lithium carbonate (Ni: Li molar ratio = 1: 1) were well pulverized and mixed in a mortar. This was heated to 400 ° C. under the flow of air and maintained at this temperature for about 2 hours until the generation of carbon dioxide gas was not observed, and pre-baking was performed.
After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.27. When compared with Example 1 (mixed powder firing), even if the final firing time is 1/3 (total heat treatment time is 1/2), the peak intensity ratio is practical as a positive electrode agent for lithium ion batteries. One or more lithium nickelates could be produced in a single firing.

[0033]

Comparative Example 7 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
Water (35.0 g) was further added to 0.0 g and lithium carbonate (17.1 g) (Ni: Li molar ratio = 1: 1), mixed and kneaded well with a grinder. After further kneading while adding an appropriate amount of water, extrusion molding was performed to a hole diameter (equivalent diameter of the through hole) of 0.8 mm to form a cylindrical chip having a length of 2 to 5 mm, and 120 ° C.
After being dried for 16 hours at 80 ° C., it is heated up to 800 ° C. at a stretch under oxygen flow (without pre-baking), and at this temperature, 6
Final firing for an hour. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.84. Example 5 and Comparative Example 7
As shown in Table 5, the peak intensity ratios of the samples obtained by X-ray diffraction measurement differ greatly depending on the presence or absence of pre-baking at 400 ° C.

[0034]

[Table 5]

[0035]

Example 9 Basic Nickel Carbonate 5 Obtained in Preparation Example 1
0.0g and 19.6g of lithium hydroxide (Ni: Li molar ratio = 1: 1) were well pulverized and mixed in a mortar. This was heated to 400 ° C. under the flow of air, and maintained at this temperature for about 2 hours until carbon dioxide generation was no longer observed, and pre-baking was performed.
After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours. The heat treatment time including the temperature raising time and the temperature lowering time was 12 hours in total. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.19.

[0036]

Example 10 The same operation as in Example 1 was performed, except that after pre-baking at 400 ° C., the flow of oxygen was changed to final baking at 850 ° C. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 1.20.

The results of Examples 9 and 10 show that lithium hydroxide may be used as the water-soluble lithium compound.

[0038]

Comparative Example 8 50.0 g of nickel hydroxide and 19.1 g of lithium carbonate (Ni: Li molar ratio = 1: 1) were well pulverized and mixed in a mortar. This was heated to 400 ° C. under the flow of air and maintained at this temperature for about 2 hours for preliminary firing. After that, the flow of oxygen was switched to the final firing at 800 ° C. for 6 hours.
The total heat treatment time including the temperature rise time and temperature fall time is 12
It was time. The peak intensity ratio of the obtained sample by X-ray diffraction measurement was 0.98. When nickel hydroxide is used instead of basic nickel carbonate as a nickel source, nickel having a peak intensity ratio of 1 or more is practical as a positive electrode material for lithium ion batteries even if firing is continuously performed in two stages having different temperature regions. Lithium oxide cannot be obtained.

[0039]

INDUSTRIAL APPLICABILITY Lithium nickel oxide, which is practical as a positive electrode material for a lithium ion battery, can be produced by firing once.

Front Page Continuation (72) Inventor Susumu Yokono 1-26 Takitaya Honcho, Niitsu City, Niigata Prefecture JGC Chemicals Co., Ltd. Central Research Laboratory

Claims (7)

[Claims] 1. A powder of a basic nickel carbonate and a powder of a water-soluble lithium compound are intimately mixed at a ratio of Ni and Li being substantially 1: 1 mol, and in the presence of an inert gas or an oxygen-containing gas. After pre-firing at a temperature in the range of 250 to 550 ° C. to substantially end the generation of carbon dioxide gas, subsequently 700 to 900 ° C. in the presence of oxygen gas or oxygen-enriched air.
The method for producing lithium nickel oxide is characterized in that final firing is performed at a temperature in the range. 2. The method for producing lithium nickelate according to claim 1, wherein the pre-baking temperature is in the range of 300 to 500 ° C. 3. A precipitate obtained by reacting a basic nickel carbonate with a water-soluble nickel compound and a compound selected from the group consisting of alkali carbonate, alkali bicarbonate, ammonium carbonate and ammonium bicarbonate in water, and filtering and drying. The method for producing lithium nickelate according to claim 1, wherein 4. The water-soluble nickel compound is nickel nitrate,
The method for producing lithium nickelate according to claim 3, which is a compound selected from the group consisting of nickel sulfate and nickel chloride. 5. The method for producing lithium nickelate according to claim 1, wherein the water-soluble lithium compound is lithium carbonate or lithium hydroxide. 6. A powder obtained by intimately mixing a powder of basic nickel carbonate and a powder of a water-soluble lithium compound in the form of a molded product in the presence of an inert gas or an oxygen-containing gas at 250 to 250.degree.
A preliminary calcination at a temperature in the range of 550 ° C. to substantially end the generation of carbon dioxide gas, followed by a final calcination at a temperature in the range of 700 to 900 ° C. in the presence of oxygen gas or oxygen-enriched air. 1. The method for producing lithium nickelate according to 1. 7. The method for producing lithium nickelate according to claim 6, wherein the pre-baking temperature is in the range of 300 to 500 ° C.