JP2003267732A - Method for manufacturing lithium-nickel compound oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a lithium-nickel compound oxide with high packing density which is industrially beneficial. <P>SOLUTION: The method for manufacturing the lithium-nickel compound oxide comprises a drying process to produce a dried material by spray-drying slurry or a solution containing a nickel compound, a mixing process to produce a raw materials mixture containing carbon of 0.5 wt.% or less by mixing the produced dried material and a lithium compound and a firing process to fire the produced raw materials mixture. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a lithium nickel composite oxide suitable as a positive electrode active material for a lithium ion secondary battery.

[0002]

2. Description of the Related Art As a positive electrode active material for a lithium ion secondary battery, a layered composite oxide such as a lithium cobalt composite oxide (LiCoO ₂ ) system, a lithium nickel composite oxide (LiNiO ₂ ) system, or a spinel structure is used. The lithium-manganese composite oxide (LiMn ₂ O ₄ ) -based lithium transition metal composite compound has a high voltage of 4 V and has a high energy density, and thus has been widely put into practical use. Or it is in the stage of practical application. Among the above-mentioned lithium-transition metal composite compounds, lithium-nickel composite oxides have been researched particularly vigorously because they have a higher capacity than other active materials.

As a method for producing the lithium-nickel composite oxide, a dry method in which a lithium compound as a raw material, a nickel compound, and other elemental compounds used as necessary are mixed and baked, or a raw material is used. Various methods are known such as a wet method in which a lithium compound, a nickel compound, and other element compounds used as necessary are dispersed in a dispersion medium such as water, and a slurry is dried and then calcined. . Among these production methods, when a lithium nickel composite oxide is produced by using a wet method, a lithium compound as a raw material, a nickel compound, and other element compounds used as necessary can be uniformly mixed, and lithium Since nickel composite oxide particles can be spherically granulated and the filling property can be improved, it is an effective method for producing a lithium nickel composite oxide. In the production of a lithium nickel composite oxide using such a wet method, a water-soluble lithium compound is generally used as a raw material in order to improve the uniformity.

[0004]

However, according to the studies by the present inventors, when the lithium nickel composite oxide is produced by the above-mentioned wet method, a water-soluble lithium compound is used as a raw material in order to further improve the uniformity. It has been found that there are the following problems when used as. (1) In the step of drying a slurry in which a lithium compound as a raw material, a nickel compound, and other elemental compounds that are used as needed are dispersed in a dispersion medium such as water, the lithium compound absorbs carbon dioxide in the atmosphere. However, the firing time in the firing step is increased to remove the carbonic acid component. In particular, in the case of a lithium nickel composite oxide, since the subsequent firing atmosphere is usually under oxygen, increasing the firing time is a particularly heavy load. (2) In a step of drying a slurry in which a lithium compound as a raw material, a nickel compound, and other element compounds used as necessary in a dispersion medium such as water are dried, the lithium compound is selectively deposited on the surface. However, the shell of the lithium compound is generated on the surface of the particles, so that the particles after drying become hollow and become a lithium nickel composite oxide having a low packing density.

An object of the present invention is to provide a method for producing a lithium nickel composite oxide having a high packing density, which is industrially advantageous.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a nickel compound,
And, other than the other elements used as needed, to the dried product obtained by spray-drying a slurry in which a dispersion medium such as water is dispersed, a lithium compound is added later, and the carbon in the raw material mixture obtained It was found that the above problems do not occur if the content is controlled, and the present invention has been completed.

That is, the gist of the present invention is as follows (1)-
It exists in (5). (1) A drying step of spray-drying a slurry or a solution containing a nickel compound to obtain a dried product, and mixing the obtained dried product and a lithium compound to obtain a raw material mixture having a carbon content of 0.5% by weight or less. A method for producing a lithium-nickel composite oxide, comprising: a mixing step of obtaining and a firing step of firing the obtained mixed raw material. (2) The production method according to (1), wherein the lithium nickel composite oxide is represented by the following general formula (I).

[0008]

Embedded image in _{Li x Ni 1-y M y} O 2- δ (I) [Formula (I), x is the number of 0.8 ≦ x ≦ 1.3,
y is a number 0 ≦ y ≦ 0.5, M is Co, Mn,
Fe, Cr, V, Ti, Cu, Al, Ga, Bi, S
n, Zn, Mg, Ge, Nb, Ta, Be, B, Ca,
Represents at least one element selected from the group consisting of Sc and Zr, δ corresponds to oxygen deficiency or excess oxygen,
It represents a number of −0.1 <δ <0.1. (3) The production method according to (1) or (2), wherein the nickel compound is at least one selected from the group consisting of nickel oxide, nickel hydroxide, and nickel nitrate. (4) The manufacturing method according to any one of (1) to (3), wherein the lithium compound is at least one selected from the group consisting of lithium hydroxide and lithium nitrate. (5) The production method according to any one of (1) to (4), wherein the lithium compound has an average particle size of 100 μm or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
Examples of the nickel compound contained in the slurry or solution include nickel oxides such as nickel oxide, nickel hydroxide, nickel oxyhydroxide, nickel nitrate,
Inorganic acid salts of nickel, excluding carbonates such as nickel sulfate,
Examples thereof include organic acid salts of nickel such as nickel acetate, nickel halides such as nickel chloride, and hydrates thereof. Since it is industrially advantageous and a good battery performance can be obtained, among them, nickel oxide, nickel hydroxide, nickel oxyhydroxide, nickel nitrate, nickel chloride can be preferably mentioned. Preferably, nickel oxide and nickel hydroxide can be mentioned. A plurality of nickel compounds may be used in combination.

If necessary, the slurry or solution containing the nickel compound may contain a compound containing an element other than the nickel compound. For example, Co, Mn, Fe, Cr, V, T may be used to replace a part of nickel sites in the lithium nickel composite oxide.
i, Cu, Al, Ga, Bi, Sn, Zn, Mg, G
A compound containing an element such as e, Nb, Ta, Be, B, Ca, Sc or Zr can be contained in the slurry or the solution. Among them, Co, Mn, Fe, Cr, V, and T are preferable from the viewpoints of battery performance and availability of raw materials.
Examples thereof include i, Cu, Al, Zn, Mg, Nb, B, Ca, and Zr, and more preferably Co, Mn, and F.
Examples thereof include e, Cr, Ti, Cu, Al and Mg. Specifically, oxides of the above elements, hydroxides, oxyhydroxides, inorganic acid salts such as nitrates and sulfates excluding carbonates,
Examples thereof include organic acid salts such as acetate, halides such as chloride, and hydrates thereof. Among them, it is industrially advantageous, and since it is possible to obtain a good battery performance, oxides of the above elements, hydroxides,
Examples thereof include inorganic acid salts such as nitrates and sulfates other than oxyhydroxides and carbonates, and hydrates thereof. A compound containing an element other than the nickel compound may be contained in combination of plural kinds. When producing a lithium nickel composite oxide, high temperature characteristics, safety, etc. can be improved by substituting a part of the nickel sites of the lithium nickel composite oxide with the above-mentioned other elements.

As the solvent of the slurry or solution, various organic solvents and inorganic solvents can be used, but it is preferable to use water from the viewpoint of industrial superiority. The compound containing an element other than the nickel compound may be dissolved or well dispersed in the solvent. The composition ratio of various components in the slurry or solution is appropriately selected according to the composition of the target lithium nickel composite oxide and the like. Further, in the slurry or solution, the transition metal compound and other components may be dissolved or dispersed in the solvent.

The concentration of the slurry or solution varies depending on the kind of the raw material compound, but is usually 0.1 to 60% by weight, preferably 0.1 to 50% by weight, and most preferably 5%.
-40% by weight. If the concentration of the slurry or solution is too low, the productivity tends to decrease, while if it is too high, the viscosity of the slurry or solution becomes too high, which may cause problems such as clogging during transfer of the slurry during spray drying. .

In the case of a slurry, the average particle size of the solid particles in the slurry is preferably as small as possible, usually 2 μm or less, preferably 1 μm or less, more preferably 0.5 μm.
m or less, on the other hand, it is difficult to obtain particles having an excessively small particle size, and therefore it is usually 0.01 μm or more, preferably 0.05
It is at least μm, more preferably at least 0.1 μm. If the solid particles in the slurry are large, problems such as blockage may occur during slurry transfer during spray drying, and the lithium nickel composite oxide obtained by firing may become non-uniform. There is. In the present invention, the average particle size of the solid content in the slurry and the average particle size of the lithium nickel composite oxide are measured by a known laser diffraction / scattering type particle size distribution measuring device.
The measurement principle of this method is as follows. That is, slurry or powder is dispersed in a dispersion medium, the sample solution is irradiated with laser light, and scattered light that is incident on particles and scattered (diffracted) is detected by a detector. The scattering angle θ (angle between the incident direction and the scattering direction) of the detected scattered light is forward scattering (0 <θ <90 °) for large particles, and side scattering or back scattering (90 °) for small particles. ° <θ <180 °)
Becomes From the measured angular distribution value, the particle size distribution is calculated using information such as the incident light wavelength and the particle refractive index. Further, the average particle size is calculated from the obtained particle size distribution. The dispersion medium used in the measurement may be, for example, a 0.1 wt% sodium hexametaphosphate aqueous solution.

The viscosity of the slurry or solution is usually 1-10.
It is 000 mPa · s. If the viscosity of the slurry or solution is too low, problems such as difficulty in obtaining clean granulated particles may occur during the production of the lithium nickel composite oxide. On the other hand, if the viscosity is too high, smooth transfer does not proceed, causing problems in handling, and problems such as difficulty in obtaining fine particles during drying may occur. The viscosity of the slurry or solution is preferably 1 to 5000 mPa.
s, more preferably 10 to 1800 mPa · s, and most preferably 100 to 1000 mPa · s.

The viscosity of the slurry or solution can be measured with a known BM type viscometer. The BM type viscometer is a measuring method that employs a method of rotating a predetermined metal rotor in a room temperature atmosphere. The viscosity of the slurry is calculated from the resistance force (twisting force) applied to the rotating shaft of the rotor when the rotor is rotated while being immersed in the slurry. However, the ambient temperature is 10 ° C to 35 ° C.
C., relative humidity means an environment of 20% RH to 80% RH.

In obtaining the lithium nickel composite oxide, the obtained slurry or solution is dried to remove the solvent. The method of drying is not particularly limited, but spray drying is preferred. By spray drying, a spherical dry raw material powder can be obtained by a simple method, and as a result, the packing density can be improved. The method of spray drying is not particularly limited, but droplets of the slurry component from the nozzle (for example, this may be simply referred to as “droplet” in the present specification) by causing gas flow and slurry to flow into the tip of the nozzle. .) Is discharged, and the scattered droplets are rapidly dried by using an appropriate drying gas temperature and an appropriate blowing rate. As the gas to be supplied as a gas flow, in addition to air (including decarbonated air), an inert gas such as nitrogen can be used, but air is usually used. It is preferable to use these under pressure. The gas flow is injected at a gas linear velocity of usually 100 m / s or more, preferably 200 m / s or more, more preferably 300 m / s or more.
If it is too small, it becomes difficult to form appropriate droplets. However, since it is difficult to obtain a too high linear velocity, the normal injection velocity is 1000 m / s or less. The nozzle to be used may have any shape as long as it can eject minute droplets, and a conventionally known one, for example, Japanese Patent No. 27970.
It is also possible to use a nozzle capable of atomizing the liquid droplets as described in Japanese Patent Laid-Open No. 80. The drying gas temperature is usually 50 ° C. or higher, preferably 70 ° C. or higher, usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, most preferably 150 ° C. or lower. If the temperature is too high, the spherical structure of the obtained granulated particles may be deformed, while if it is too low, problems such as powder sticking and blockage due to water condensation at the powder outlet may occur. .

By drying the slurry or solution, granulated particles as a dried product are obtained. The granulated particle size (secondary particle size) of the dried product is preferably 50 μm or less, more preferably 30 μm or less in terms of average particle size, from the viewpoint of battery performance. However, since it tends to be difficult to obtain a particle size that is too small, the particle size is usually 0.1 μm or more, preferably 1 μm or more, and more preferably 3 μm or more. The particle size of the granulated particles can be controlled by appropriately selecting the drying conditions, for example, the spray type in the case of spray drying, the pressurized gas flow supply rate, the slurry supply rate, the drying temperature and the like. In the present invention, the average particle size of the lithium compound is measured by a known laser diffraction / scattering type particle size distribution measuring device. The measurement principle of this method is as described above. From the measured angular distribution value, the particle size distribution is calculated using information such as the incident light wavelength and the particle refractive index. Further, the average particle size is calculated from the obtained particle size distribution. Examples of the dispersion medium used in the measurement include ethanol.

The lithium compound to be mixed with the dried product is, for example, an inorganic acid salt such as a lithium oxide, a hydroxide, an oxyhydroxide, a nitrate or a sulfate other than carbonate,
Examples thereof include organic acid salts such as acetate, halides such as chloride, and hydrates thereof. Among them, from the viewpoint of battery performance, preferably lithium hydroxide, lithium nitrate,
Examples thereof include lithium sulfate and lithium oxide, and more preferable examples include lithium hydroxide, lithium nitrate and lithium oxide. Most preferably, it is lithium hydroxide. A plurality of lithium compounds may be used in combination.

The particle size of the above-mentioned lithium compound is usually 500 μm in average particle size in order to improve the mixing property with the dried product obtained by spray drying and to improve the battery performance.
m or less, preferably 100 μm or less, more preferably 50 μm or less, and most preferably 20 μm or less. On the other hand, those having a too small particle diameter have an average particle diameter of usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.2 μm or more, and most preferably 0. It is 5 μm or more. In the present invention, the average particle size of the granulated particles after spray drying is
It is measured by a known laser diffraction / scattering type particle size distribution measuring device. The measurement principle of this method is as described above. From the measured angular distribution value, the particle size distribution is calculated using information such as the incident light wavelength and the particle refractive index. Further, the average particle diameter is calculated from the obtained particle diameter distribution. At that time, if the granulated particles are crushed to become primary particles, that portion is omitted and calculated. When measuring the granulated particles after spray drying, in order to prevent the granulated particles from being crushed during the measurement, it is preferable to measure the granulated particles after firing at 800 ° C. for about 30 minutes in advance. The dispersion medium used in the measurement may be, for example, a 0.1 wt% sodium hexametaphosphate aqueous solution.

The dried product obtained by drying the above slurry or solution and the lithium compound are mixed to form a mixed powder. The mixing method is not particularly limited, but it is preferable to use a powder mixing apparatus which is generally used for industrial use. As the atmosphere in the system for mixing, it is preferable to mix in an inert gas in order to prevent carbon dioxide absorption in the air. The mixing composition ratio of the powders to be mixed is appropriately selected according to the composition of the target lithium nickel composite oxide and the like.

The above-mentioned mixed powder can be further mixed with other compounds, if necessary. For example, when not containing other element compounds in the slurry or solution, after mixing the slurry or solution with a lithium compound after drying,
Further, it can be mixed with other element compounds. When a part of another elemental compound is contained in the slurry or solution, the slurry or solution may be mixed with the lithium compound after drying, and then the remaining other elemental compound may be further mixed. Also in this case, the mixing method is not particularly limited,
From the viewpoint of uniformity, it is preferable to use an industrially used powder mixing device for mixing.

The carbon content in the raw material mixture obtained by mixing is 0.5% by weight or less, preferably 0.3% by weight or less, and more preferably 0.2% by weight or less. When the carbon content is high, there are problems such as an increase in firing load and deterioration of battery performance. On the other hand, since it is difficult to obtain a mixed raw material having a too low carbon content, the carbon content is usually 0.005% by weight or more, preferably 0.01% by weight or more.
It should be more than weight%. In order to keep the carbon content in the above range, it is necessary to avoid carbonates and organic acid salts as raw materials to be subjected to calcination as much as possible, and to avoid absorption of carbonic acid components in the atmosphere, in an environment where the atmosphere is cut off. It is preferable to adopt the method of storing the mixed raw material in step 1. In particular, it is more preferable to employ a method of storing under an inert gas atmosphere. The carbon content of each compound or a mixed raw material thereof can be measured by, for example, combustion in an oxygen stream (high-frequency heating furnace type) -infrared absorption method.

The above-obtained mixed powder can be subjected to a firing treatment to obtain a lithium nickel composite oxide. The firing temperature during the firing treatment is usually 500 ° C. or higher, preferably 55
It is 0 ° C. or higher, and usually 1000 ° C. or lower, preferably 900 ° C. or lower. If the firing temperature is too low, it is difficult to obtain a lithium nickel composite oxide having good crystallinity, and the effect of improving the packing density may be reduced. If the firing temperature is too high, a phase other than the desired lithium nickel composite oxide may be generated, or a lithium nickel composite oxide with many defects may be generated. When the temperature is raised from room temperature to the above reaction temperature, in order to carry out the reaction more uniformly, for example, the temperature is gradually raised at a temperature of 5 ° C. or less per minute, or the temperature is temporarily stopped during the process. Alternatively, a holding time at a constant temperature may be added.

The firing time during the firing treatment is usually 1 hour or more and 100 hours or less, preferably 2 hours or more and 50 hours or less. If the time is less than the above range and the time is too short, it is difficult to obtain a lithium nickel composite oxide having good crystallinity, and a reaction time that is too long beyond this range is not practical. The atmosphere during the firing treatment is usually in the presence of oxygen. In particular,
The firing can be performed in air or in a gas atmosphere having an oxygen concentration of 20% or more. When firing in air, it is preferable to use decarbonated air. Preferably in decarbonated air or in a gas atmosphere having an oxygen concentration of 20% or more,
More preferably, it is a pure oxygen atmosphere.

In order to obtain a lithium-nickel oxide having few crystal defects, it is preferable to cool slowly to a certain temperature after the above firing, and cooling to 800 ° C., preferably 600 ° C. or less at 5 ° C./min. It is preferable to slowly cool at a speed. The heating device used for firing is not particularly limited as long as it can achieve the above temperature and atmosphere,
For example, a box furnace, a tubular furnace, a tunnel furnace, a rotary kiln or the like can be used.

The lithium nickel composite oxide produced in this way is usually formed from secondary particles in which fine primary particles are aggregated. The size of the primary particles can be controlled by the particle size of the raw material, the firing temperature, the firing time, and the like, and the particle size of the secondary particles is the slurry or solution production conditions, spray drying conditions, and further It can be controlled by crushing after firing, classification conditions and the like. In order to use the lithium nickel composite oxide as a positive electrode active material of a lithium ion secondary battery, it is composed of secondary particles having a particle diameter of 1 to 100 μm in which primary particles having a particle diameter of 0.1 to 10 μm are aggregated and containing nitrogen. Specific surface area by adsorption is 0.1-5m ² / g
Are preferred.

The lithium nickel composite oxide obtained is
It is usually represented by the following general formula (I).

[0028]

Embedded image _{Li x Ni 1-y M y} O 2- δ (I) wherein, x represents, 0.8 ≦ x ≦ 1.3, preferably 0.9
Represents the number of ≦ x ≦ 1.1, y corresponds to the amount of substitution with the element M other than nickel, and 0 ≦ y ≦ 0.5, preferably 0 ≦
x is a number of 0.3, M is Co, Mn, Fe, C
r, V, Ti, Cu, Al, Ga, Bi, Sn, Zn,
Represents at least one element selected from the group consisting of Mg, Ge, Nb, Ta, Be, B, Ca, Sc and Zr, δ corresponds to oxygen deficiency or excess oxygen, and -0.1 <
It represents a number of δ <0.1, preferably −0.05 <δ <0.05.

The lithium nickel oxide represented by the above general formula (I) is characterized by excellent battery characteristics such as battery capacity, rate characteristics, cycle characteristics, storage characteristics, and safety. The lithium-nickel composite oxide produced by the method of the present invention can be used as an electrode active material such as a positive electrode active material to produce a lithium ion secondary battery.

A lithium secondary battery usually has a positive electrode, a negative electrode and an electrolyte layer. As an example of a lithium secondary battery,
A secondary battery including a positive electrode, a negative electrode, an electrolytic solution, and a separator can be mentioned. In this case, an electrolyte exists between the positive electrode and the negative electrode, and the separator is arranged between them so that the positive electrode and the negative electrode do not come into contact with each other. The positive electrode usually contains the lithium nickel oxide and the binder. In addition, the positive electrode is usually formed by forming a positive electrode layer containing the positive electrode material and a binder on a current collector.

Such a positive electrode layer is produced by applying a slurry of a lithium nickel oxide, a binder and, if necessary, a conductive agent, etc. in a solvent to a positive electrode current collector and drying it. You can In the positive electrode layer, LiMn ₂
An active material capable of inserting and extracting lithium ions other than the lithium-nickel-based oxide, such as O ₄ , LiMnO ₂ , LiCoO ₂ , and LiFePO ₄ , may be further contained.

The proportion of the active material in the positive electrode layer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, usually 99.9% by weight or less, preferably 99% by weight or less. Is. If it is too large, the mechanical strength of the electrode tends to be poor, and if it is too small, the battery performance such as capacity tends to be poor. Examples of the binder used for the positive electrode include polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and EPDM.
(Ethylene-propylene-diene terpolymer), SBR
(Styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber, polyvinyl acetate,
Examples thereof include polymethylmethacrylate, polyethylene, nitrocellulose and the like. The proportion of the binder in the positive electrode layer is usually 0.1% by weight or more, preferably 1% by weight or more,
More preferably, it is 5% by weight or more, usually 80% by weight.
Or less, preferably 60% by weight or less, more preferably 4
It is 0% by weight or less, and most preferably 10% by weight or less.
When the proportion of the binder is too low, the active material cannot be sufficiently retained and the mechanical strength of the positive electrode is insufficient, which may deteriorate battery performance such as cycle characteristics, while when it is too high, the battery capacity and conductivity May reduce sex.

The positive electrode layer usually contains a conductive agent in order to enhance conductivity. Examples of the conductive agent include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and carbon material such as amorphous carbon such as needle coke. The proportion of the conductive agent in the positive electrode is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 1% by weight or more and usually 50% by weight or less, preferably 30% by weight or less, It is preferably 15% by weight or less. If the proportion of the conductive agent is too low, the conductivity may be insufficient, and conversely, if it is too high, the battery capacity may decrease.

The slurry solvent is not particularly limited as long as it can dissolve or disperse the binder, but an organic solvent or water is usually used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N
-Dimethylaminopropylamine, ethylene oxide,
Tetrahydrofuran, water, etc. can be mentioned.

The thickness of the positive electrode layer is usually 1 to 1000 μm,
It is preferably about 10 to 200 μm. If it is too thick, the conductivity tends to decrease, and if it is too thin, the capacity tends to decrease. As the material of the current collector used for the positive electrode, aluminum, stainless steel, nickel-plated steel or the like is used, and aluminum is preferable. The thickness of the current collector is usually 1 to 1000 μm, preferably 5 to 500 μm
It is a degree. If it is too thick, the capacity of the lithium secondary battery as a whole may be reduced, and if it is too thin, the mechanical strength may be insufficient.

The positive electrode layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the active material. The negative electrode active material used for the negative electrode of the secondary battery may be lithium or a lithium alloy such as a lithium aluminum alloy, but a carbon material having higher safety and capable of absorbing and releasing lithium is preferable.

The carbon material is not particularly limited, but graphite, coal-based coke, petroleum-based coke, carbide of coal-based pitch, carbide of petroleum-based pitch, or carbide of these pitches subjected to oxidation treatment, needle coke, pitch coke, Examples thereof include phenol resins, carbides such as crystalline cellulose and the like, and carbon materials obtained by partially graphitizing these, furnace black, acetylene black, pitch carbon fibers and the like.

Further, as the negative electrode active material, SnO, SnO
₂, Sn_1-xM_xO (M = Hg, P, B, Si, Ge
Is Sb, where 0 ≦ x <1), Sn₃O₂(OH)₂, Sn
_3-xM _xO₂(M = Mg, P, B, Si, Ge, Sb or
Mn, where 0 ≦ x <3), LiSiO₂, SiO₂, L
iSnO₂Etc. can be mentioned. Among these,
Using a mixture of two or more selected from
May be.

The negative electrode is usually formed by forming a negative electrode layer on a current collector as in the case of the positive electrode. As the binder used at this time, the conductive agent and the like used as necessary, and the slurry solvent, the same ones as those used for the positive electrode can be used. Further, as the current collector of the negative electrode, copper, nickel,
Stainless steel, nickel plated steel or the like is used, and copper is preferably used.

When a separator is used between the positive electrode and the negative electrode, a microporous polymer film is usually used, and polytetrafluoroethylene, polyester, nylon,
Those composed of polyolefin polymers such as cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene and polybutene are used. Further, a non-woven filter of glass fiber or the like, or a non-woven filter of glass fiber and polymer fiber can also be used. The chemical and electrochemical stability of the separator is an important factor. From this point of view, the polyolefin-based polymer is preferable, and from the viewpoint of the self-closing temperature which is one of the purposes of the battery separator, it is preferably made of polyethylene.

In the case of the polyethylene separator, ultrahigh molecular weight polyethylene is preferable from the viewpoint of shape retention at high temperature, and the lower limit of its molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1,500,000. On the other hand, the upper limit of the molecular weight is preferably 5,000,000, more preferably 4,000,000, and most preferably 3,000,000. If the molecular weight is too small, the clogging property becomes too high, which causes a problem in use at high temperature. If the molecular weight is too large, the fluidity may be too low to block the pores of the separator when heated.

As the electrolyte forming the electrolyte layer in the lithium secondary battery, for example, known organic electrolytes, polymer solid electrolytes, gel electrolytes, inorganic solid electrolytes and the like can be used. Is preferred. The organic electrolytic solution usually contains an organic solvent and a solute. The organic solvent is not particularly limited, and examples thereof include carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, chlorinated hydrocarbons, amines, esters, amides, phosphoric acid. Ester compounds and the like can be used. When these representative ones are specifically listed, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, tetrahydrofuran, 2-
Methyltetrahydrofuran, 1,4-dioxane, 4-
Methyl-2-pentanone, 1,2-dimethoxyethane,
1,2-diethoxyethane, γ-butyrolactone, 1,
3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethylsulfoxide, phosphoric acid Examples thereof include trimethyl and triethyl phosphate, and these can be used alone or as a mixed solvent of two or more kinds.

The above organic solvent preferably contains a high dielectric constant solvent for dissociating the electrolyte. Here, the high dielectric constant solvent has a relative dielectric constant of 20 at 25 ° C.
The above compounds are meant. In the high dielectric constant solvent, it is preferable that the electrolytic solution contains ethylene carbonate, propylene carbonate, γ-butyrolactone, and a compound in which the hydrogen atom thereof is replaced with another element such as halogen or an alkyl group. The ratio of the high dielectric constant compound in the electrolytic solution is preferably 20% by weight or more, more preferably 30% by weight.
It is at least 40% by weight, most preferably at least 40% by weight. This is because if the content of the compound is small, desired battery characteristics may not be obtained.

The solute to be dissolved in this solvent is not particularly limited, but any conventionally known solute can be used, such as LiClO ₄ , LiAsF ₆ , LiPF ₆ and Li.
BF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, CH
₃ SO ₃ Li, CF ₃ SO ₃ Li, LiN (SO ₂ CF ₃ ) ₂ ,
Examples thereof include lithium salts such as LiN (SO ₂ C ₂ F ₅ ) ₂ and LiC (SO ₂ CF ₃ ) _{3, and} at least one or more of these can be used. In addition, CO ₂ , N ₂ O, C
An additive such as O, SO ₂ or a gas such as polysulfide S _x ²⁻ that forms a good film capable of efficiently charging / discharging lithium ions on the surface of the negative electrode is added to the above-mentioned single or mixed solvent at an arbitrary ratio. Good.

When the polymer solid electrolyte is used, the known polymer can be used. In particular, it is preferable to use a polymer having high ionic conductivity with respect to lithium ions, and for example, polyethylene oxide, polypropylene oxide, polyethyleneimine and the like are preferably used. It is also possible to add the above solvent to the polymer together with the above solute and use it as a gel electrolyte.

When an inorganic solid electrolyte is used, a known crystalline or amorphous solid electrolyte can be used as this inorganic material. Examples of the crystalline solid electrolyte include Li
I, Li ₃ N, Li _{1 + x} M _x Ti _2-x (PO ₄ ) ₃ (M
= At least one selected from the group consisting of Al, Sc, Y and La), Li _0.5-3x RE _{0.5 + x} TiO ₃ (provided that R is
E = La, Pr, Nd and at least one selected from the group consisting of Sm) and the like. Examples of the amorphous solid electrolyte include 4.9LiI-34.1Li ₂ O-61B ₂ O ₅ , 3
Oxide glass such as 3.3Li ₂ O-66.7SiO ₂ or 0.45LiI
-0.37Li ₂ S-0.26B ₂ S ₃ , 0.30LiI-.42Li ₂ S-0.2
Examples thereof include sulfide glass such as 8SiS ₂ . At least one of these can be used.

[0047]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, the viscosity of the slurry in the examples was measured by a BM type viscometer (manufactured by Tokimec). The measurement is performed in a room temperature atmosphere, a specific metal rotor is fixed to the rotary shaft of the apparatus main body, the rotor is immersed in a slurry liquid, the rotor is rotated, and the scale after 3 minutes is read, using a conversion table, The slurry viscosity was calculated from the rotor and rotation speed. <Example 1> (1) Production of Li _1.05 Ni _0.80 Co _0.15 Al _0.05 NiO, Co (OH) ₂ and AlOOH were mixed with Ni: C.
Weighed so that o: Al = 0.80: 0.15: 0.05 (molar ratio), and added pure water to this to obtain a solid content concentration of 30.
A wt% slurry was prepared. While stirring the slurry, a circulating medium stirring type wet pulverizer (manufactured by Shinmaru Enterprises Co., Ltd .: Dyno-mill KDL-A type) was used to pulverize until the average particle size of the solid content in the slurry became 0.25 μm. did. The time required for crushing was 3 hours. The viscosity of this slurry was 820 mPa · s.

The slurry was spray-dried using a two-fluid nozzle type spray dryer (manufactured by Okawara Kakoki Co., Ltd .: LT-8 type spray dryer). At this time, air was used as the dry gas, the discharge gas introduction rate was 50 L / min, and the dry gas inlet temperature was 90 ° C. The average particle size of the obtained dried product was 6.8 μm. The average particle size of the granulated particles after spray drying was 6.8 μm. The average particle size of the granulated particles after spray drying was determined using a laser diffraction / scattering type particle size distribution measuring device (manufactured by Horiba, Ltd .: LA-920 type particle size distribution measuring device). Specifically, the granulated particles after spray-drying, which were previously baked at 800 ° C. for 30 minutes,
Disperse in a 0.1% sodium hexametaphosphate aqueous solution at room temperature in the air and adjust the transmittance between 70% and 95%,
The average particle size was determined from the measured particle size distribution. The relative refractive index set at that time was 1.24. Next, the granulated particles obtained by spray drying and LiO having an average particle size of 20 μm or less
The _{H · H 2 O Li: Ni} = 1.05: 0.80 were uniformly mixed in proportions such that the composition (molar ratio). The carbon content at this stage was 0.12% by weight (HORIBA, Ltd .: EMIA-520 carbon-sulfur analyzer used). Then, it baked at 740 degreeC and 6 hours in oxygen atmosphere. As a result, cobalt-aluminum-substituted lithium nickelate having a molar ratio composition almost as charged was obtained. (2) Measurement of powder press density The powder to be measured is introduced into a 25 mmφ cylinder, and 4
The density of the powder obtained when a load of 06 kgf / cm ² was applied was defined as the powder press density. (3) Preparation of lithium-ion secondary battery Li _1.05 Ni _0.80 Co _0.15 Al _0.05 that is a positive electrode active material, acetylene black that is a conductive agent, and PTF that is a binder.
E (polytetrafluoroethylene) in a weight ratio of 75:
The mixture was mixed at a ratio of 20: 5, kneaded sufficiently using an agate mortar, and formed into a sheet.
mm and 12 mm for high temperature cycle characteristics measurement, and then 9 m in diameter to an Al current collector with a diameter of 16 mm
pressure of 14 MPa for m, 20 for diameter of 12 mm
After pressure bonding under a pressure of MPa and vacuum drying at 120 ° C. for 3 hours, a positive electrode was obtained.

A 2032 type coin battery was assembled with the obtained positive electrode in a glove box in an argon atmosphere. A lithium metal having a diameter of 12 mm and a thickness of 1 mm was used for the negative electrode for measuring the rate characteristic. Also, for the negative electrode for measuring high-temperature cycle characteristics, a copper foil having a thickness of 20 μm has an average particle size of 8 to 10 μm.
Polyvinylidene fluoride was used as a binder and the polyvinyl powder was weighed at a weight ratio of 92.5: 7.5, dispersed in N-methylpyrrolidone, and the coated product was dried and had a diameter of 12 mm. Punched into 0.5 ton / cm ²
What was pressed under the pressure of was used. 1 mole / electrolyte
A mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7 using 1 liter of LiPF ₆ as a supporting salt was used. (4) Evaluation of Battery Performance With respect to the battery manufactured as described above, 0.2 mA / cm 2 was measured in a voltage range of 3.2 V to 4.2 V.
The initial discharge capacity (mAh / g) per unit weight of the positive electrode active material was measured when the rate evaluation test was performed at a current density of ² . Comparative Example 1 LiOH.H ₂ O, NiO, Co (OH) ₂
And AlOOH, Li: Ni: Co: Al = 1.0
It is weighed to be 5: 0.80: 0.15: 0.05 (molar ratio), and pure water is added to this to obtain a solid content concentration of 30% by weight.
Was prepared. While stirring this slurry,
Using a circulating medium agitation type wet pulverizer (manufactured by Shinmaru Enterprises Co., Ltd .: Dyno-mill KDL-A type), pulverization was performed until the average particle diameter of the solid content in the slurry became 0.29 μm. The time required for crushing was 3 hours. The viscosity of this slurry was 640 mPa · s.

The slurry was spray-dried using a two-fluid nozzle type spray dryer (manufactured by Okawara Kakoki Co., Ltd .: LT-8 type spray dryer). At this time, air was used as the dry gas, the discharge gas introduction rate was 50 L / min, and the dry gas inlet temperature was 90 ° C. The carbon content at this stage was 1.38% by weight. Next, the dry powder is kept under an oxygen atmosphere at 650 ° C. for 10 hours,
Further, it was baked at 740 ° C. for 24 hours. As a result, cobalt-aluminum-substituted lithium nickelate having a molar ratio composition almost as charged was obtained.

With respect to the measurement of the powder press density, the production of the lithium ion secondary battery, and the evaluation of the battery performance, the production and evaluation of lithium nickel oxide was carried out in the same manner as in Example 1. <Comparative Example 2> Preparation and evaluation of lithium nickel oxide in the same manner as Comparative Example 1 except that nitrogen gas was used as a drying gas during spray drying and firing was performed at 740 ° C for 6 hours in an oxygen atmosphere. I went. The carbon content after spray drying was 0.08% by weight.

Table 1 shows the firing time, the carbon content of the raw material before the firing, the powder press density, and the battery evaluation result.

[0053]

[Table 1]

[0054]

According to the present invention, a highly productive lithium nickel composite oxide can be obtained. Further, according to the present invention, a lithium nickel composite oxide having a high packing density can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nei Tsuda             1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa             Within Mitsubishi Chemical Corporation F-term (reference) 4G048 AA03 AA04 AC06                 5H029 AJ14 AK03 AL02 AL12 AM02                       AM07 AM12 AM16 BJ03 CJ02                       CJ08 HJ01 HJ02 HJ05                 5H050 AA19 BA17 CA03 CB02 CB07                       CB12 CB29 EA02 EA09 EA10                       EA22 EA24 GA02 GA10 HA01                       HA02 HA05

Claims (5)

[Claims] 1. A raw material having a carbon content of 0.5% by weight or less by spray-drying a slurry or solution containing a nickel compound to obtain a dried product, and mixing the dried product with a lithium compound. A method for producing a lithium nickel composite oxide, comprising: a mixing step of obtaining a mixture; and a firing step of firing the obtained mixed raw material. 2. The method according to claim 1, wherein the lithium nickel composite oxide is represented by the following general formula (I). ## STR1 _{Li x Ni 1-y M y} O 2- δ (I) [Formula (I), x is the number of 0.8 ≦ x ≦ 1.3,
y is a number 0 ≦ y ≦ 0.5, M is Co, Mn,
Fe, Cr, V, Ti, Cu, Al, Ga, Bi, S
n, Zn, Mg, Ge, Nb, Ta, Be, B, Ca,
Represents at least one element selected from the group consisting of Sc and Zr, δ corresponds to oxygen deficiency or excess oxygen,
It represents a number of −0.1 <δ <0.1. ] 3. The production method according to claim 1, wherein the nickel compound is at least one selected from the group consisting of nickel oxide, nickel hydroxide, and nickel nitrate. 4. The lithium compound is at least one selected from the group consisting of lithium hydroxide and lithium nitrate, and any one of claims 1 to 3 is characterized.
Manufacturing method described in. 5. The average particle size of the lithium compound is 100 μm.
It is the following, The manufacturing method as described in any one of Claim 1 thru | or 4.