JP3130813B2 - Lithium nickel composite oxide, method for producing the same, and positive electrode active material for secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high charge / discharge capacity and a small decrease in capacity even when the number of cycles is increased.
The present invention relates to a novel lithium nickel composite oxide having excellent stability, a method for producing the same, and a positive electrode active material for a secondary battery.

[0002]

2. Description of the Related Art In recent years, as portable electronic devices have become more portable,
There is an increasing demand for a lithium secondary battery that is small and lightweight and has a high energy density in place of a nickel / cadmium battery.

As a positive electrode active material that can be used in such a lithium secondary battery, LiC which is a layered compound capable of intercalating and deintercalating lithium is used.
oO ₂ and LiNiO ₂ are known. Among them, Li
NiO ₂ is expected because of its higher electric capacity than LiCoO ₂ .

Usually, LiNiO ₂ is composed of a Li component (LiOH,
And Li ₂ CO _3, LiNO _3, etc.), because it is produced by the so-called dry method of reacting after mixing Ni component (hydroxides, carbonates, etc.) and to a respective powder form, it must be long high temperature firing In particular, in the case of Ni, divalent to trivalent
It is difficult to obtain a high value, and high-temperature firing for a long time is essential. As a result, crystal growth proceeds, but on the other hand, there is volatilization of Li or N
The purity of iO is reduced due to by-products of iO.

On the other hand, the inventor of the present invention has disclosed in Japanese Patent Application No. Hei.
In the invention of No. 80895 (JP-A-8-130013), LiNiO ₂ of high purity and high crystallinity can be produced in a short time by producing a uniform precursor of Li component and Ni component using a wet method. Succeeded in manufacturing.

However, in LiNiO ₂ , many L
When i is desorbed (during charging), the structure becomes unstable due to the two-dimensional structure, so that the essential problem of poor cyclability of the Li secondary battery could not be completely overcome. Therefore, even if the technique of Japanese Patent Application No. 6-80895 was used, the effect of improving the cycle characteristics was recognized to some extent, but the long-term cycle characteristics of 100 cycles or more were still insufficient. For this reason, many attempts have been made to stabilize the structure by replacing a part of Ni with another component (third component). For example, JP-A-63-29905
No. 6 discloses Li _y Ni _x Co _1-x O ₂ in which Co is dissolved.
(Where x is 0 <x ≦ 0.75, and y is y ≦ 1
And JP-A-5-283076 discloses L.
Li _{y in} which Ti, V, Mn or Fe is dissolved in iNiO ₂
Ni _1-x Me _x O ₂ (where Me is Ti, V, Mn and Fe
X is 0 <x <0.6, and
(y is 0.2 <y ≦ 1.3).

[0007] However, the method of dissolving the third component is also performed by a method called the above-mentioned dry method, and it is difficult to uniformly dissolve the third component. In addition, it is necessary to perform high-temperature and long-time firing, and to perform several pulverizing steps. For this reason, the L
As in the case of iNiO ₂ , Li was volatilized and NiO was produced as a by-product to lower the purity, so that the cycleability was not sufficiently improved. In addition, the dry method is an uneconomical method with poor production efficiency due to the necessity of a long-time firing and pulverization step.

[0008] In addition, in these dry methods, since the calcination time is inevitably long, it is impossible to freely adjust the particle size while keeping the crystallinity and purity high.

In such a situation, attempts have been made to produce a spherical material in order to increase the packing density. For example, in Japanese Patent Application Laid-Open No. Hei 7-105950, spherical Ni (OH) ₂ To produce LiNiO ₂ spherical particles. This technique uses spherical Ni (OH) ₂ as a starting material and obtains LiNiO ₂ in a spherical form by a dry method for the purpose of simply increasing the packing density. In particular, the primary particle diameter and purity of LiNiO ₂ are reduced. It was not something to keep in mind and was not satisfactory. Japanese Patent Application Laid-Open No. Hei 6-333562 discloses a technique for producing spherical products having a diameter of 0.1 to 1.1 μm by using a mist dry method. In this technique, when used in a battery because the particle size is too small, it is not practical as a battery, such as passing through a separator. In particular, in the case of LiNiO ₂ , storage stability is poor if primary particles are too small. Therefore, there has been a problem that moisture absorption causes a failure to stably provide good battery characteristics.

[0010] Further, it is known that when left at high temperatures, for example, in a car, during the daytime, even when the temperature is returned to normal temperature, the positive electrode active material is greatly deteriorated, the discharge performance is deteriorated, and the performance as a battery is greatly reduced. ing.

As a method of preventing the deterioration of the positive electrode active material at a high temperature, since the smaller the primary particle diameter is, the more remarkable the deterioration is, attention has been paid to how to increase the primary particle diameter of the active material.

As a method of increasing the primary particle diameter of the positive electrode active material and improving the storage stability or discharge characteristics at high temperatures, for example, in the case of LiCoO ₂ , attempts have been made to increase the primary particle diameter by improving the firing conditions. JP-A-6-243897 (0.1-2.0 μm), JP-A-6-325793 (0.01-5 μm) and JP-A-7-14579 (0.01-5 μm)
m)].

In Japanese Patent Application Laid-Open No. 8-55624, it is easy to increase the primary particle diameter in a LiCoO ₂ system, for example, by adding Bi oxide to a raw material source to make the average diameter of crystallites 2 μm or more.

[0014] On the other hand, in the LiNiO ₂ system, no example of such primary particles grown large has yet been found. The reason for this is that, as described above, in the synthesis of Li _y Ni _1-x M _x O ₂ to which LiNiO ₂ or the third component (M) is added, the reactivity is poor. This is because baking must be performed, and Li is easily volatilized. As a result, an incomplete crystal in which crystal growth hardly proceeds and which has many lattice defects is obtained. For this reason, calcination must be performed at as high a temperature as possible within the allowable temperature range, and as a result, only fine particles having a primary particle size of less than 1 μm are obtained.

[0015]

DISCLOSURE OF THE INVENTION The present invention relates to a novel lithium-nickel composite oxide having sufficiently developed crystals, high purity, high charge / discharge capacity and excellent stability, a large primary particle size, It is an object of the present invention to provide a method for producing the lithium-nickel composite oxide whose shape can be freely set, and a positive electrode active material for a secondary battery containing the composite oxide as an active ingredient.

[0016]

Means for Solving the Problems The inventors of the present invention have the following general formula (I): Li _y-x1 Ni _1-x2 M _x O ₂ (I) (where M is Co, Al, Fe, Mg or Mn, x = x
₁ + x is _2, x is 0 <x ≦ 0.5, x ₁ is 0 ≦ x ₁ <
0.2, x ₂ is 0 <x ₂ ≦ 0.5, y is 0.9 ≦ y
≦ 1.3), a novel lithium nickel composite oxide having a sufficiently developed crystal with high purity and excellent stability of high charge / discharge capacity was created by a wet method. The production method of the present invention has a feature that the size and shape of the primary particle diameter of the intended lithium nickel composite oxide can be freely set.

That is, the present invention relates to a compound represented by the general formula (I): Li _y-x1 Ni _1-x2 M _x O ₂ (I) wherein M is a group consisting of Al, Fe, Co, Mn and Mg. X = x ₁ + x ₂ (where (i) when M is Al or Fe, 0 <x ≦
Indicates 0.2, x ₁ is 0, x ₂ represents the x, (ii) M is C
o For or Mn, indicates 0 <x ≦ 0.5, x ₁ is 0, x ₂ represents the x, if it is (iii) M is Mg is, 0
<Shows the x ≦ 0.2, x ₁ is _{0 <x 1 <0.2, x} 2 is 0 <
x ₂ <0.2), and y represents 0.9 ≦ y ≦ 1.3]
And (0) at the Miller index hkl of X-ray diffraction.
Diffraction peak ratio on the 03) and (104) planes (003)
/ (104) is 1.2 or more, (006) plane and (10)
1) The diffraction peak ratio (006) / (101) on the plane is 0.1.
13 or less, BET surface area of 0.1 to ² m ² / g, total Ni
The ratio of Ni ³⁺ to 99% by weight or more, the average particle diameter D is 5 to 100 μm, and the particle size distribution
0% is 2D or less, is a spherical secondary particle having an uneven surface when observed by a scanning electron microscope (SEM), and the primary particle diameter of the spherical secondary particle is longer than that of a long particle observed by SEM. A lithium-nickel composite oxide characterized by being uniform particles having a particle diameter distributed in a range of 0.2 to 3.0 μm and having an average major particle diameter of 0.3 to 2.0 μm. .

Further, the present invention relates to a compound represented by the general formula (I): Li _y-x1 Ni _1-x2 M _x O ₂ (I) wherein M is selected from the group consisting of Al, Fe, Co, Mn and Mg. X = x ₁ + x ₂ (where (i) when M is Al or Fe, 0 <x ≦
Indicates 0.2, x ₁ is 0, x ₂ represents the x, (ii) M is C
o For or Mn, indicates 0 <x ≦ 0.5, x ₁ is 0, x ₂ represents the x, if it is (iii) M is Mg is, 0
<Shows the x ≦ 0.2, x ₁ is _{0 <x 1 <0.2, x} 2 is 0 <
x ₂ <0.2), and y represents 0.9 ≦ y ≦ 1.3]
And (0) at the Miller index hkl of X-ray diffraction.
Diffraction peak ratios (00) on the 03) and (104) planes
3) / (104) is 1.2 or more, diffraction peak ratio on (006) plane and (101) plane (006) / (101)
Is not more than 0.13, and the average major axis of primary particles observed by SEM is 1 to 10 μm.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The lithium nickel composite oxide represented by the above general formula according to the present invention is specifically represented by the following general formula (Ia)
To (Ic).

Li _y Ni _1-x M _x O ₂ (Ia) (wherein, M represents Al or Fe, and x represents 0 <
x ≦ 0.2, and y represents 0.9 ≦ y ≦ 1.3).
This is a composite oxide in which Al or Fe, which does not have battery characteristics even in the form of MO ₂ , is dissolved in a trivalent form in a small amount and uniformly, thereby stabilizing the structure and improving the cycle characteristics.

If the value of x is less than 0.01, the amount of solid solution of Al or Fe is small, and the stabilization of the structure is insufficient.
It is not preferable because the cycle property is deteriorated. On the other hand, when the value of x exceeds 0.2, the solid solution is insufficient, impurities are generated, and the discharge capacity is rapidly reduced, and the original function as a positive electrode active material of a lithium secondary battery for high capacity is intended. Lose.

In addition, the following general formula (Ib) Li _y Ni _1-x M _x O ₂ (Ib) (wherein, M represents Co or Mn, and x represents 0 <x
.Ltoreq.0.5 and y represents 0.9.ltoreq.y.ltoreq.1.3).
In the form of MO ₂ , Co or Mn having battery characteristics
Is a solid oxide in which a relatively large amount is dissolved to stabilize the structure and maintain a high battery capacity. If the value of x is 0.
If it is less than 01, the solid solution amount of Co or Mn is small, and the stability of the structure is insufficient, which is not preferable.

If the value of x exceeds 0.5, in the case of cobalt, the amount of solid solution is too large to lower the discharge capacity, and also expensive cobalt is dissolved in a large amount, so that it is not economically advantageous. . In the case of manganese, the discharge capacity is originally small, and if the value of x exceeds 0.5, the original function as a positive electrode active material of a lithium secondary battery intended for high capacity is lost.

In the general formula (I), the following general formula (Ic) wherein M is Mg: Li _y-x1 Ni _1-x2 Mg _x O ₂ (Ic) (where x = x ₁ + x ₂ and x Is 0 <x ≦ 0.2, x
₁ is 0 <x ₁ <0.2, x ₂ is 0 <x ₂ <0.2, and y is 0.9
≦ y ≦ 1.3), the magnesium having no battery characteristics per se is uniformly dissolved in a part of the lithium layer and a part of the nickel layer to form a structure. It is a composite oxide that is stabilized and has improved cycle characteristics. If the value of x is less than 0.01, M
g is small, and the stability of the structure is insufficient, which is not preferable. When the value of x exceeds 0.2, the solid solution is insufficient and impurities are generated, so that the discharge capacity is rapidly reduced, and the original function as a positive electrode active material of a lithium secondary battery for high capacity is lost. .

The lithium nickel composite oxide of the present invention is composed of a spherical product obtained by a wet-spray drying method described later and a large primary particle product obtained by a press method using the spray-dried product as a raw material for firing.

First, a spherical product using the spray drying method will be described. This spherical article has the following properties.

The first feature is that impurities are not detected by X-ray analysis and the purity is high. Moreover, the diffraction peak ratio (003) / (004) on the (003) plane and the (104) plane at the Miller index hkl of X-ray diffraction is 1.2 or more,
Diffraction peak ratio at (006) plane and (101) plane (00
6) / (101) is 0.13 or less, N
High purity with i ³⁺ ratio of 99% by weight or more.

Usually, when a part of Ni is replaced by another component (third component), the stability of the structure is increased, but the purity is reduced in proportion to the amount of the replacement.

According to the present invention, a high-purity composite oxide can be obtained although Al, Fe, Mg, Co or Mn is dissolved in a solid solution. That is, since the third component, Al or Fe, has a trivalent valence in the structure, the structural instability of Ni due to inflow and outflow of Li can be eliminated. In the case of Mg, Mg is dissolved in a part of the lithium layer and a part of the nickel layer, so that the instability of the structure can be eliminated. Co
Alternatively, when Mn is uniformly dissolved, the structural instability of Ni due to the inflow and outflow of Li can be eliminated. The most important feature of the present invention is to make the third component as small and uniform as possible so as not to be unnecessarily large.

This is correlated with a manufacturing method which can be called a water-liquid method (wet method) which will be described later, and a size of primary particles which will be described later. A stable, highly pure and highly crystalline composition can be obtained.

The second feature is that uniform particles having a long diameter distributed in the range of 0.2 to 3.0 μm as observed by SEM are uniform particles having an average long diameter of 0.3 to 2.0 μm. In that the primary particles are

Generally, in the intercalation compound represented by LiMO ₂ , the size of primary particles is important when considering the inflow and outflow of Li. The finer the primary particles, the better the ionic conductivity inside the solid, and the easier it is for Li to enter and exit from the outside.

On the other hand, from the viewpoint of crystallinity, 0.2 μm
In the following primary particles, the crystals do not sufficiently develop and necessarily have low purity. On the other hand, when the thickness is less than 0.2 μm, the storage stability is poor, so that it is not possible to stably exhibit good battery characteristics due to moisture absorption. Furthermore, it is desirable that the primary particles have a uniform particle size from the viewpoint of quality stability. From the above viewpoints, the inventors of the present invention have conducted intensive studies, and as a result, observed by SEM, uniform particles having a long diameter distributed in a range of 0.2 to 3.0 μm and having an average long diameter. 0.3
It has been found that the products of the present invention having a thickness of from 2.0 to 2.0 μm, preferably from 0.3 to 1.0 μm, have suitable performance.

The third feature is that the particles are formed into a spherical shape by a wet-spray drying method described later, and the spherical secondary particles have an average particle diameter D of 5%.
３００300 μm, 10% of particle size distribution is 0.5D or more, 90
% Is 2D or less, which means that the surface is in an uneven state as can be seen by SEM observation.

The particle diameter ratio (major axis / minor axis) of the spherical secondary particles observed by SEM may be slightly larger when the particles are crushed after firing. Usually, the particles fall within a range of 1.5 or less at the maximum and 1.2 or less on average, and 90% or more of the particles are particles having a uniform particle size distributed to 1.3 or less.

From these properties, not only is it suitable for close packing, but for example, when used in batteries, the electrolyte,
It can be seen that the contact area with the conductive agent or the like is increased, and this is advantageous from the fact that Li enters and exits from the outside.

The particle size of the spherical secondary particles is 5 to 100 μm.
m can be set as desired, but when used as a battery material, an average particle size of about 5 to 30 μm is desirable from the viewpoint of workability. Further, the BET specific surface area is 0.1 to ² m ² / g.
When used as a battery material, the viscosity of the electrolyte does not increase, so that the dielectric constant does not decrease.

The lithium nickel composite oxide represented by the general formula (I) of the present invention can be produced by the following production method.

The lithium nickel composite oxide of the present invention comprises:
Formula ^{_{(II) Ni 1-x M}} p x (OH) 2-nz (A n-)
_{[Z + (px−2x) / n]} · mH ₂ O (I
I) (wherein, M represents one kind selected from the group consisting of Al, Fe, Co, Mn and Mg, and p is the valence of M and 2 ≦ p ≦ 3
Are ^{shown, A n-n-valent} anion, x, respectively z and m 0 <x ≦ 0.2,0.03 ≦ z ≦ 0.3,0 ≦ m <
A positive number that satisfies the range of 2) and a water-soluble lithium compound in an aqueous medium with Li /
The reaction is performed under the condition of a molar ratio of (Ni + M) = 0.9 to 1.3, the obtained slurry is spray-dried, and then fired in an oxidizing atmosphere at about 600 ° C. to 900 ° C. for about 4 hours or more. Can be manufactured.

As the water-soluble lithium compound and the basic metal salt, those containing anions that volatilize during firing are used.

As the lithium compound, for example, LiO
One or more of H, LiNO ₃ , Li ₂ CO _3, or a hydrate thereof can be selected.

[0042] In basic metal salt of the general formula (II) display, A as the ^n-, for _{^{example, NO 3 -, Cl -,}} Br -,
It can be selected from compounds represented by CH ₃ COO ⁻ , CO ₃ ²⁻ , SO ₄ ^{2− and the} like.

In the above general formula (II), ^p of M p is
When M is Al or Fe, it is trivalent and is a hydrotalcite compound. (However, in the case of Fe, 2
Although a part of the compound may be partially contained, it is liable to become trivalent in a reaction with a lithium compound, a drying step, and the like, and there is no particular problem. ) When M is Co or Mn, p may be divalent, trivalent, or a mixture thereof, and there is no particular problem. When M is Mg, p is divalent.

In these compounds, from the viewpoints of yield, reactivity, effective utilization of resources and oxidation promoting effect, LiOH is used as the lithium compound, and A ⁿ is used as the basic metal salt represented by the general formula (II). A combination in which a basic metal nitrate in which ^— is NO ₃ ^— is selected from the viewpoint of battery characteristics.

As the basic metal salt, it is recommended that the crystallites of the primary particles are fine particles of 0.1 μm or less as measured by Scherrer method from the viewpoint of uniformity.

The fine particles preferably have a BET specific surface area of 10 m ² / g or more, preferably 40 m ² / g or more, and more preferably 100 m ² / g or more from the viewpoint of surface reactivity. Incidentally, with respect to the BET specific surface area, when the basic metal salt in the aqueous solution is dried and measured, the primary particles which are fine particles are aggregated at the time of drying, and the BET specific surface area of the aggregate is measured. When the cohesion is strong, nitrogen gas does not enter and the value is small. Therefore, the specific surface area of the basic metal salt that reacts with the lithium compound actually in Mizueki indicates a larger value, but has a highly reactive surface, was 10 m ² or more than the above circumstances.

The basic metal salt having this specific composition has a layered structure, and both the chemical composition and the crystal structure are Ni _1-x M _x (O
H) It is a substance close to ₂ and, as described above, is microcrystalline and has a high surface activity. Therefore, when a lithium compound such as LiOH is added, very good Li _y-x1 Ni _1-x2 M
forming a precursor _x O _2.

Only when a basic metal salt having such a specific composition is used, the Li of the present invention having high purity and high crystal perfection is used.
_{y-x1 Ni 1-x2 M} x O 2 can be obtained. Ni _1-x M _x (OH) ₂ is inferior in reactivity with a lithium compound to a basic metal salt, and conversely, in a basic metal salt, when the amount of anions increases,
As well as deviating from the layered structure, the anion at the time of calcination acts to inhibit the formation of Li _y-x1 Ni _1-x2 M _x O ₂ , and it is possible to obtain the target compound with high purity and high crystal perfection. Can not.

The basic metal salt used here is Ni _1-x M _x
An aqueous solution of a salt, with respect to Ni _1-x M x salt, about 0.7 to 0.
It can be produced by adding and reacting 95 equivalents, preferably about 0.8 to 0.95 equivalents of an alkali under reaction conditions of about 80 ° C. or lower. Examples of the alkali used here include hydroxides of alkali metals such as sodium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide, and amines. It is more preferable that the basic metal salt is aged at 20 to 70 ° C. for 0.1 to 10 hours after the synthesis. Next, by-products are removed by washing with water, and a lithium compound is added.

The slurry obtained by such a reaction is dried by a spray drying method. The spray drying method, which can be dried instantaneously and can obtain a spherical substance, is based on the spherical granulation property, uniformity of the composition (in a drying method requiring a long drying time such as shelf drying, band drying, etc., Li migrates to the surface). And a non-uniform composition is obtained).

When sintering a spherical product having a uniform composition obtained by a wet method or a spray drying method as it is, a sintering temperature of 600.
To 800 ° C, preferably 700 to 750 ° C, firing time 4
It may be carried out in an oxygen stream for more than an hour, preferably about 4 to 20 hours. If the calcination time is 20 hours or more, not only does the cost increase, but also the volatilization of Li causes the trivalent ratio of Ni to be rather low, resulting in poor purity.

In the known technique of the dry method relating to the calcination, since the Li component and the Ni component are absolutely inhomogeneous, the Li component and the Ni component react, and Ni becomes divalent to trivalent.
When it comes to valence, Ni is difficult to become trivalent from divalent
In view of the fact that firing for at least 20 hours is required, the manufacturing method of the present invention for firing a uniform spray-dried product as it is is very economical and advantageous.

Next, the composite oxide salt having a large primary particle of the present invention, a method for producing the same, and a positive electrode active material for a secondary battery containing this composite oxide as an active ingredient will be described in detail below.

The average major axis of this large primary particle product is 1 to 1
0 μm.

If the above-described spherical product obtained by the spray drying method is used as the positive electrode active material of the battery, the type of the third component metal and the amount of solid solution can be appropriately set so that the desired battery capacity can be maintained. The cycle characteristics are sufficiently improved. However, there is an increasing demand for public awareness of safety, and there is growing debate that batteries that are actually used should be expected to be used under severe conditions. In particular, in the current situation where the function for safety as a composite battery including other battery materials (cathode, electrolyte, separator, etc.) other than the positive electrode active material is immature, lithium batteries that can withstand use at high temperatures There is a strong demand for positive electrode active materials for secondary batteries.

The present invention has been made to meet this need, and provides a positive electrode active material having the following characteristics.

That is, the composition is the same as that of the above-mentioned spherical product, and the characteristic is (00) in the Miller index hkl of X-ray diffraction.
Diffraction peak ratio at (3) and (104) planes (003) / (1)
04) is 1.2 or more, the diffraction peak ratio (006) / (101) on the (006) plane and the (101) plane is 0.13 or less, and the average major axis of primary particles observed by SEM is 1 to 10 μm.
m, more preferably 2 to 10 μm.

The lithium-nickel composite oxide is a novel lithium-nickel composite oxide in which primary particles having sufficiently developed crystals have a large average major axis and are more excellent in stability.

Also, the positive electrode active material having the primary particles increased is made of Ni ³⁺
Is preferably as high as 99% or more. B
The ET specific surface area is as small as 0.01 to ¹ m ² / g due to the increase in the particles. When used as a battery material, the viscosity of the electrolytic solution is not increased, and the reactivity with the electrolytic solution is small.

The lithium-nickel composite oxide having a large primary particle according to the present invention is prepared by using a basic metal salt represented by the above general formula (II) as a starting material and adding water-soluble lithium to an aqueous medium in the form of Li / (Ni + M). Are reacted under the condition that the molar ratio of the resulting mixture is 0.9 to 1.3, the obtained slurry is spray-dried, and the spray-dried product is obtained by press molding.

As a production method, a method of press-forming a spray-dried product and firing it, or a method of once firing a spray-dried product, press-forming the same, and then refiring are applied.

The first production method is a method in which a spray-dried product is press-molded and then fired in an oxidizing atmosphere at 600 ° C. to 900 ° C. for about 4 hours or more.

The spherical product obtained by the above spray drying method is
It is excellent in fluidity, moldability and filling property, and has a static pressure of usually 500 to 3000 kg / cm ² , preferably 800 to 1 according to a conventional method, for example, using a Brinell hardness tester.
It can be formed into a press-formed product at 500 kg / cm ² .

The press molding is extremely significant in that the intermolecular movement distance is reduced and the crystal growth during firing is promoted.

The above press-formed product can be fired as it is.

The calcination temperature is usually 600 to 900 ° C., preferably 750 to 800 ° C., and the calcination time is usually 4 hours or more, preferably 10 to 72 hours under an oxygen stream.

By the press molding, the crystal growth of primary particles is promoted during firing, and a composite oxide having large primary particles can be obtained.

The method of pressing and molding this spherical product is as follows.
Unlike the method of firing the spherical article as it is, even if the firing time is 20 hours or more, the contact surface becomes smaller because of compression, and the volatilization of Li and the by-product of NiO hardly occur.
A composite oxide having high purity and high crystallinity can be obtained.

In the second production method, the spray-dried product is directly baked in an oxidizing atmosphere at 600 ° C. to 900 ° C. for about 0.5 hour or more, and the obtained baked product is pulverized if necessary.
Press molding in the same manner as in the first manufacturing method, and re-firing at 600 ° C. to 900 ° C. for about 1 hour or more in an oxidizing atmosphere. This method requires a total time required for firing compared to the first manufacturing method. Has the advantage of being shorter.

The spherical particles obtained by the spray drying do not increase the primary particles even if they are calcined for a long time.

Even after firing for 20 hours, the average particle size is 2 μm or less,
The average particle size after firing for about 2 to 3 μm.

Further, even if press molding is performed by a dry method, as shown in a comparative example described later, the average particle size of the product fired for 20 hours is 1 μm or less. Even if the firing time is extended, the particle size does not change much.

Therefore, the production method according to the present invention, which is a combination of the wet method, the spray drying method and the press molding method, is extremely advantageous in increasing the primary particles.

Further, although the cause is not clear by pressing, the distance between powder and the movement between Li molecules and Ni molecules is reduced.
And the by-product of NiO are suppressed, and a composite oxide having high purity and high crystallinity can be obtained.

The composite oxide having a large primary particle has a low reactivity due to a large primary particle and a small battery capacity, as will be apparent from the examples described later. ) Increases.

The calcined product of lithium nickel composite oxide thus obtained may be suitably ground to a desired particle size depending on the application.

The lithium nickel composite oxide of the present invention
As will be apparent from Examples and Comparative Examples described later, when used as a positive electrode active material of a secondary battery, a high discharge capacity of 130 to 200 mAh / g can be achieved, and a capacity decrease of 10% or less even after the 100th charge / discharge cycle. Rate and stable
Can be used effectively.

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

The method for measuring the BET specific surface area of the fired product, the method of measuring the primary particles by the Scherrer method,
The method for measuring the value is as follows.

[Method of Measuring BET Specific Surface Area] The fired product was weighed as a sample as it was in a cell, and nitrogen 30%, helium 7
What was heated and degassed under the flow of 0% mixed gas,
It was measured by the BET one-point continuous flow method. The BET specific surface area measuring instrument is manufactured by MONOSO manufactured by Yuasa Ionics Inc.
RB was used.

[Scherrer method] Assuming that the crystal has no distortion and the crystallite size is uniform, and the spread of the diffraction line width is based only on the crystallite size. This is a method to determine the size.

Dhkl = (kλ) / (βcosθ) (Equation 1) In the expression, Dhkl (angstrom) is the size of a crystallite in a direction perpendicular to the (hkl) plane, and λ (angstrom) is the wavelength of X-ray. , Β (rad) indicates a diffraction line width, θ (゜) indicates a diffraction angle, and k indicates a constant.

[0083] [Measurement of Ni ^3+] Ni ³⁺ represents a percentage of the total Ni, was determined by a redox titration. A sample (0.2 g) is dissolved in a 0.25 M FeSO ₄ -3.6 N sulfuric acid solution, 2 ml of concentrated phosphoric acid is added, and the mixture is titrated with 0.1 N potassium permanganate. Similarly, a blank test was performed, and the following equation 2
Then, Ni ³⁺ % based on the total Ni in the sample is determined. In Formula 2, f is a factor of a 0.1N potassium permanganate solution, X ₀ is a blank test titer (ml), and X is a titer (m
l) and m are sample amounts (g), B is Ni content (%), and A is 5.871.

The ratio (%) of Ni ^{3+ to} all Ni in the sample = [fX (X ₀ −X) × A × 10] / (m × B) (Formula 2)

[0085]

【Example】

Example 1 A mixed aqueous solution of 2.0 mol / l of aluminum nitrate and nickel nitrate was prepared so that the molar ratio of Al / (Ni + Al) was 0.03.
/ L sodium hydroxide aqueous solution was simultaneously added so as to have a pH of 9.0, and continuously added at a temperature of 50 ° C under strong stirring.
Added in 0 minutes. The obtained reaction product was separated by filtration, washed with water, and suspended in water to give 1 mol / l of Ni _0.97 Al.
_0.03 (OH) ₂ (NO ₃ ) _0.03 slurry was obtained. Atomic ratio of Li / (Ni + A) to (Ni + Al) in this slurry
l) An aqueous solution of 3.5 mol / l lithium hydroxide corresponding to 1.05 was prepared, dropped into the slurry, reacted, and then spray-dried. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace (TF-630 type manufactured by Yamada Electric). The chemical composition of the fired product was Li _1.03 Ni _0.97 Al _0.03 O ₂ .

Example 2 A mixed aqueous solution of 2.0 mol / l of aluminum nitrate and nickel nitrate was prepared so that the molar ratio of Al / (Ni + Al) = 0.02.
/ L sodium hydroxide aqueous solution was simultaneously added so as to have a pH of 9.5.
Added in 0 minutes. The obtained reaction product was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.98 Al.
_0.02 (OH) ₂ (NO ₃ ) _0.02 slurry was obtained. The atomic ratio of this slurry to Ni is Li / (Ni + Al) = 1.0.
After an amount of 3.5 mol / l aqueous lithium hydroxide solution corresponding to 3 was dropped into the slurry and reacted, spray drying was performed. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was Li _1.01 Ni _0.98 Al _0.02 O ₂ .

Example 3 2.0 m so that the Al / (Ni + Al) molar ratio = 0.1
ol / l of a mixed aqueous solution of aluminum nitrate and nickel nitrate was prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide were simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction product was filtered, washed with water, and suspended in water to obtain a 1 mol / l Ni _0.9 Al _0.1 (OH) ₂ (NO ₃ ) _0.1 slurry. The atomic ratio of this slurry to Ni is Li
/(Ni+Al)=3.5mo in an amount corresponding to 1.05
After a 1 / l aqueous solution of lithium hydroxide was added dropwise and reacted, spray drying was performed. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was LiNi _0.9 Al _0.1 O ₂ .

Example 4 2.0 m so that the Al / (Ni + Al) molar ratio = 0.2
ol / l of a mixed aqueous solution of aluminum nitrate and nickel nitrate was prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide were simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction product was filtered, washed with water, and suspended in water to obtain a 1 mol / l Ni _0.8 Al _0.2 (OH) ₂ (NO ₃ ) _0.2 slurry. The atomic ratio of this slurry to Ni is Li
/(Ni+Al)=3.5mo in an amount corresponding to 1.05
After a 1 / l aqueous solution of lithium hydroxide was added dropwise and reacted, spray drying was performed. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product is Li _1.01 Ni _0.8 Al _0.2 O ₂
Met.

Example 5 The spray-dried product obtained in Example 3 was analyzed using a Brinell hardness tester.
Press molding was performed at a static pressure of 000 kg / cm ² .

The molded product was placed in an alumina boat, fired at 750 ° C. for 72 hours in an oxygen atmosphere in a tubular furnace, and allowed to cool.
This was crushed to obtain a LiNi _0.9 Al _0.1 O ₂ powder.

Example 6 A mixed aqueous solution of 2.0 mol / l of iron nitrate and nickel nitrate was prepared so that the molar ratio of Fe / (Ni + Fe) = 0.03. An aqueous sodium hydroxide solution was simultaneously added so as to have a pH of 9.5, and was continuously added at a temperature of 50 ° C. with vigorous stirring for 60 minutes. The obtained reaction product was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.97 Fe _0.03 (OH).
₂ (NO ₃ ) _0.03 slurry was obtained. (Ni +
Fe / atomic ratio of Li / (Ni + Fe) = 1.03
A 3.5 mol / l aqueous lithium hydroxide solution was prepared in an amount corresponding to the above, and the mixture was dropped into the slurry and reacted, followed by spray drying. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace.
The chemical composition of the fired product was Li _1.02 Ni _0.97 Fe _0.03 O ₂ .

Example 7 2.0 m so that the molar ratio of Fe / (Ni + Fe) = 0.1.
ol / l of an aqueous solution of iron nitrate and nickel nitrate is prepared, and this mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5.
The mixture was continuously added at a temperature of 25 ° C. with vigorous stirring, and the obtained reaction product was filtered, washed with water, and then suspended in water to give 1 mol.
/ L of Ni _0.9 Fe _0.1 (OH) ₂ (NO ₃ ) _0.1 slurry was obtained. Atomic ratio of Li / (Ni +
(Al) = 3.05 mol / l aqueous solution of lithium hydroxide in an amount corresponding to 1.05 was added dropwise and reacted, followed by spray drying. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was LiNi _0.9 Fe _0.1 O ₂ .

Example 8 2.0 m so that the molar ratio of Fe / (Ni + Fe) = 0.2.
ol / l of an aqueous solution of iron nitrate and nickel nitrate is prepared, and this mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5.
The mixture was continuously added at a temperature of 25 ° C. with vigorous stirring, and the obtained reaction product was filtered, washed with water, and then suspended in water to give 1 mol.
/ L of Ni _0.8 Fe _0.2 (OH) ₂ (NO ₃ ) _0.2 slurry was obtained. Atomic ratio of Li / (Ni +
(Al) = 3.05 mol / l aqueous solution of lithium hydroxide in an amount corresponding to 1.05 was added dropwise and reacted, followed by spray drying. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was LiNi _0.8 Fe _0.2 O ₂ .

Example 9 The spray-dried product obtained in Example 7 was treated with a Brinell hardness tester to obtain 1
Press molding was performed at a static pressure of 000 kg / cm ² .

The molded product was placed in an alumina boat, calcined at 750 ° C. for 20 hours in an oxygen atmosphere in a tubular furnace, and allowed to cool.
This was crushed to obtain LiNi _0.9 Fe _0.1 O ₂ powder.

Example 10 1.0 was selected so that the molar ratio of Mn / (Ni + Mn) was 0.03.
A mixed aqueous solution of mol / l manganese nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous sodium hydroxide solution are continuously added at pH 8.5 and a temperature of 25 ° C under strong stirring, After filtering the obtained reaction product and washing with water,
1 mol / l Ni _0.97 Mn by suspending in water
_0.03 (OH) _1.97 (NO ₃ ) _0.03 slurry was obtained (the BET specific surface area of the dried basic nitrate was 147.18).
m ² / g, and the primary particle diameter (crystallite) was 44.1 angstroms as determined from the half width of the peak near 2θ = 60 ° in XRD by the Scherrer method. ). The atomic ratio of Li / (Ni
+ Mn) = 1.05, an aqueous solution of 3.0 mol / l lithium hydroxide was added dropwise and reacted, and then spray-dried. The resulting dried gel was placed in an alumina boat, calcined in an oxygen atmosphere at 750 ° C. for 5 hours in a tubular furnace, and crushed in a mortar to obtain LiNi _0.97 Mn _0.03 O ₂ powder.

Example 11 The following procedure was performed so that the molar ratio of Mn / (Ni + Mn) = 0.1.
A mixed aqueous solution of 0 mol / l manganese nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous sodium hydroxide solution are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.9 Mn _0.1 (OH) _1.9 (NO ₃ ) _0.1.
A slurry was obtained. The atomic ratio of this slurry to Ni is L
3.0 m in an amount corresponding to i / (Ni + Mn) = 1.05
ol / l aqueous solution of lithium hydroxide was dropped and reacted.
Spray drying was performed. The obtained dried product was put in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace to obtain LiNi _0.9 Mn _0.1 O ₂ powder.

Example 12 1.0 m so that the molar ratio of Mn / (Ni + Mn) = 0.4.
ol / l of manganese nitrate and nickel nitrate was prepared, and the mixed aqueous solution and 1.0 mol / l of sodium hydroxide aqueous solution were simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction mixture was filtered, washed with water, and suspended in water.
A mol / l Ni _0.6 Mn _0.4 (OH) _1.7 (NO ₃ ) _0.3 slurry was obtained. The atomic ratio of Li / Ni to this slurry is Li /
(Ni + Mn) = 3.0 mol in an amount corresponding to 1.05
After reacting by dropwise addition of an aqueous solution of / l lithium hydroxide, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace,
LiNi _0.6 Mn _0.4 O ₂ powder was obtained.

Example 13 The spray-dried product obtained in Example 11 was measured using a Brinell hardness tester.
Press molding was performed at a static pressure of 1000 kg / cm ² .

The molded product was placed in an alumina boat, calcined in an oxygen atmosphere at 750 ° C. for 20 hours in a tubular furnace, and allowed to cool.
This was crushed to obtain LiNi _0.9 Mn _0.1 O ₂ .

Example 14 The procedure was repeated so that the molar ratio of Co / (Ni + Co) = 0.03.
A mixed aqueous solution of 0 mol / l cobalt nitrate and nickel nitrate was prepared, and the mixed aqueous solution and a 2.0 mol / l aqueous sodium hydroxide solution were added simultaneously so as to have a pH of 9.0. The lower was added continuously over 60 minutes. The obtained reaction product was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.97 Co _0.03 (OH).
₂ (NO ₃ ) _0.03 slurry was obtained. The (Ni
+ Co) with an atomic ratio of Li / (Ni + Co) = 1.0
A 3.5 mol / l aqueous solution of lithium hydroxide in an amount corresponding to 5 was prepared, dropped into the slurry, reacted, and then spray-dried. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product is Li _1.03 Ni _0.97 Co _0.03 O
_{Was 2} .

Example 15 1.0 m so that the Co / (Ni + Co) molar ratio was 0.1.
ol / l of a mixed aqueous solution of cobalt nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.9 Co _0.1 (OH) _1.9 (NO ₃ ) _0.1.
A slurry was obtained. The atomic ratio of this suspension to Ni is Li
/ (Ni + Co) = 3.0 mol in an amount corresponding to 1.05
After reacting by dropwise addition of an aqueous solution of / l lithium hydroxide, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace,
LiNi _0.9 Co _0.1 O ₂ powder was obtained.

Example 16 1.0 m so that the molar ratio Co / (Ni + Co) = 0.2.
ol / l of a mixed aqueous solution of cobalt nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction mixture was filtered, washed with water, and suspended in water.
A mol / l Ni _0.8 Co _0.2 (OH) _1.8 (NO ₃ ) _0.2 slurry was obtained. The atomic ratio of Li / Ni to this slurry is Li /
3.0 mol of (Ni + Co) = 1.05
After reacting by dropwise addition of an aqueous solution of / l lithium hydroxide, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace,
LiNi _0.8 Co _0.2 O ₂ powder was obtained.

Example 17 1.0 m so that the molar ratio of Co / (Ni + Co) = 0.3.
ol / l of a mixed aqueous solution of cobalt nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The precipitate obtained was filtered, washed with water, and suspended in water.
A _0.3 mol / l Ni _0.7 Co _0.3 (OH) _1.7 (NO ₃ ) _0.3 slurry was obtained. The atomic ratio of Li / Ni to this slurry is Li /
3.0 mol of (Ni + Co) = 1.05
After reacting by dropwise addition of an aqueous solution of / l lithium hydroxide, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace,
LiNi _0.7 Co _0.3 O ₂ powder was obtained.

Example 18 1.0 m so that the molar ratio Co / (Ni + Co) = 0.4.
ol / l of a mixed aqueous solution of cobalt nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The precipitate obtained was filtered, washed with water, and suspended in water.
A _0.3 mol / l Ni _0.6 Co _0.4 (OH) _1.7 (NO ₃ ) _0.3 slurry was obtained. The atomic ratio of Li / Ni to this slurry is Li /
(Ni + Co) = 1.05 3.0 mol /
After 1 l aqueous solution of lithium hydroxide was dropped and reacted, spray drying was performed. The obtained dried product was put in an alumina boat, calcined in an oxygen atmosphere at 750 ° C. for 5 hours in a tubular furnace, and crushed in a mortar to obtain LiNi _0.6 Co _0.4 O ₂ powder.

Example 19 1.0 m so that the molar ratio of Co / (Ni + Co) = 0.2.
ol / l of a cobalt nitrate and nickel nitrate mixed aqueous solution was prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous sodium hydroxide solution were continuously added at pH 11.5 and a temperature of 25 ° C. under strong stirring, The obtained reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l Ni _0.8 %.
A slurry of Co _0.2 (OH) _1.7 (NO ₃ ) _0.3 was obtained. The molar ratio of this suspension to Ni is Li / (Ni + Co) =
After an aqueous solution of 3.0 mol / l lithium hydroxide in an amount corresponding to 1.05 was dropped and reacted, spray drying was performed. The obtained spray-dried product was measured using a Brinell hardness tester at 1300 k
Press molding was performed at a static pressure of g / cm ² . The molded product is placed in an alumina boat and placed in a tubular furnace in an oxygen atmosphere for 75 minutes.
Baking at 0 ° C. for 72 hours, after cooling, crushing and LiNi _0.8
A Co _0.2 O ₂ powder was obtained.

Example 20 The spray-dried product obtained in Example 15 was measured for 1
Press molding was performed at a static pressure of 000 kg / cm ² .
The press-formed product was placed in an alumina boat, fired in a tubular furnace at 750 ° C. for 20 hours in an oxygen atmosphere, allowed to cool, and then crushed to obtain a LiNi _0.9 Co _0.1 O ₂ powder.

Example 21 A mixed aqueous solution of 1.0 mol / l of magnesium nitrate and nickel nitrate was prepared so that the molar ratio of Mg / (Ni + Mg) was 0.049.
/ L aqueous sodium hydroxide solution at pH 11.0, temperature 2
The mixture was continuously added at 5 ° C. with vigorous stirring, and the resulting reaction mixture was filtered, washed with water, and then suspended in water to give 1 mol / mol.
1 of Ni _0.951 Mg _0.049 (OH) _1.7 (NO ₃ ) _0.3 slurry was obtained (the BET specific surface area of the dried basic nitrate was 169.4 m ² / g, and the primary particle size (crystallite )
The value obtained from the peak half-width at around 2θ = 60 ° in XRD by the Scherrer method was 32.3 Å. ). The atomic ratio of this slurry to Ni is Li
/(Ni+Mg)=3.0 mol in an amount corresponding to 1.0
After reacting by dropwise addition of an aqueous solution of / l lithium hydroxide, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace,
The mixture was crushed in a mortar to obtain LiNi _0.97 Mg _0.05 O ₂ powder.

Example 22 The spray-dried product obtained in Example 15 was directly placed in an alumina boat and calcined in an oxygen atmosphere at 750 ° C. for 5 hours in a tubular furnace, allowed to cool, pulverized, and then subjected to a Brinell hardness tester. 1300
Press molding was performed at a static pressure of kg / cm ² . The press-formed product was put again in an alumina boat, refired in an oxygen atmosphere at 800 ° C. for 1 hour in a tubular furnace, allowed to cool, and then crushed to obtain a LiNi _0.9 Co _0.1 O ₂ powder.

Comparative Example 1 A 1.0 mol / l aqueous solution of sodium hydroxide was added to 500 ml of a 2.0 mol / l aqueous solution of nickel nitrate.
1900 ml corresponding to a Ni molar ratio of 1.9 was added under stirring, and the resulting reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l of Ni (OH) _1.97 (NO ₃ ).
_{A 0.03} slurry was obtained. 3.5 mol / l of an amount corresponding to an atomic ratio of Li / Ni = 1.05 to Ni of the slurry
An aqueous solution of lithium hydroxide was prepared, dropped into the slurry and allowed to react, and then spray-dried. The obtained dried gel was placed in an alumina boat and placed in a tubular furnace in an oxygen atmosphere for 75 minutes.
Baking was performed at 0 ° C. for 5 hours. The chemical composition of the fired product is Li _1.02
NiO ₂ .

Comparative Example 2 1.05 mol of lithium hydroxide, 0.97 of nickel hydroxide
Mol and 0.03 mol of aluminum hydroxide were sufficiently dry-mixed and pulverized in a mortar, and then pelletized to a size of 14 mm in diameter and 2 mm in thickness, and calcined at 750 ° C. for 5 hours in an oxygen atmosphere. The chemical composition of the fired product is Li _1.04 Ni _0.97 Al
_0.03 O ₂ .

Comparative Example 3 1.05 mol of lithium hydroxide, 0.97 mol of nickel hydroxide and 0.03 mol of iron oxide were thoroughly dry-mixed and pulverized in a mortar, and then pelletized to a size of 14 mm in diameter and 2 mm in thickness. ,
This was fired at 750 ° C. for 5 hours in an oxygen atmosphere. The chemical composition of the fired product was Li _1.04 Ni _0.97 Fe _0.03 O ₂ .

Comparative Example 4 1.05 mol of lithium hydroxide, 0.97 of nickel hydroxide
Mol and 0.03 mol of manganese dioxide were sufficiently dry-mixed and pulverized in a mortar, and then pelletized to a size of 14 mm in diameter and 2 mm in thickness, and calcined at 750 ° C. for 5 hours in an oxygen atmosphere. The chemical composition of the fired product is Li _1.04 Ni _0.97 Mn _0.03 O
_{Was 2} .

Comparative Example 5 1.05 mol of lithium hydroxide, 0.97 of nickel hydroxide
Mol and 0.03 mol of cobalt hydroxide were thoroughly dry-mixed and pulverized in a mortar, and then pelletized to a size of 14 mm in diameter x 2 mm in thickness, and calcined at 750 ° C for 5 hours in an oxygen atmosphere. The chemical composition of the fired product is Li _1.04 Ni _0.97 Co _0.03 O
_{Was 2} .

Comparative Example 6 1.05 mol of lithium hydroxide, 0.97 of nickel hydroxide
After sufficiently dry-mixing and pulverizing 0.03 mol of magnesium oxide and 0.03 mol of magnesium oxide in a mortar, the mixture was pelletized into a size of 14 mm in diameter and 2 mm in thickness, and calcined at 750 ° C for 5 hours in an oxygen atmosphere. The chemical composition of the fired product is Li _1.04 Ni _0.97 Mg _0.03
It was O _2.

Comparative Example 7 2.0 m so that the Al / (Ni + Al) molar ratio = 0.3.
ol / l of a mixed aqueous solution of aluminum nitrate and nickel nitrate was prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide were simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The resulting precipitate was filtered, washed with water, and suspended in water to obtain a 1 mol / l Ni _0.7 Al _0.3 (OH) ₂ (NO ₃ ) _0.3 slurry. The atomic ratio of this slurry to Ni is Li
/ (Ni + Al) = 3.0mo in an amount corresponding to 1.05
After a 1 / l aqueous solution of lithium hydroxide was added dropwise and reacted, spray drying was performed. The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was LiNi _0.7 Al _0.3 O ₂ .

Comparative Example 8 2.0 m so that the molar ratio of Fe / (Ni + Fe) = 0.3.
ol / l of an aqueous solution of iron nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added at pH 8.5, and the temperature is 25 ° C.
The reaction mixture was filtered, washed with water, and suspended in water to obtain a 1 mol / l Ni _0.7 Fe _0.3 (OH) ₂ (NO ₃ ) _0.3 slurry. . The atomic ratio of this slurry to Ni is Li / (Ni + Fe).
After an aqueous solution of 3.0 mol / l lithium hydroxide in an amount corresponding to 1.05 was dropped and reacted, spray drying was performed.
The obtained dried product was put in an alumina boat and fired at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace. The chemical composition of the fired product was LiNi _0.7 Fe _0.3 O ₂ .

Comparative Example 9 1.0 m so that the molar ratio of Mg / (Ni + Mg) = 0.3.
ol / l of magnesium nitrate and nickel nitrate to prepare a mixed aqueous solution, and this mixed aqueous solution and 1.0 mol / l of sodium hydroxide aqueous solution were continuously added at pH 11.0 at a temperature of 25 ° C under strong stirring, Filtering the resulting reaction mixture,
After washing with water, 1 mol / l Ni
_A slurry of _0.7 Mg _0.3 (OH) _1.7 (NO ₃ ) _0.3 was obtained. The atomic ratio of the slurry to Ni is Li / (Ni + Mg) =
After an aqueous solution of 3.0 mol / l lithium hydroxide in an amount corresponding to 1.0 was added dropwise and reacted, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined at 750 ° C. for 5 hours in an oxygen atmosphere in a tubular furnace to obtain LiNi _0.7 Mg _0.3
O ₂ powder was obtained.

COMPARATIVE EXAMPLE 10 1.0 m so that the molar ratio of Mn / (Ni + Mn) = 0.6.
ol / l of manganese nitrate and nickel nitrate was prepared, and the mixed aqueous solution and 1.0 mol / l of sodium hydroxide aqueous solution were continuously added at pH 8.5 and at a temperature of 25 ° C. under strong stirring. The obtained reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.4
A slurry of Mn _0.6 (OH) _1.7 (NO ₃ ) _0.3 was obtained. The atomic ratio of this slurry to Ni is Li / (Ni + Mn) =
After an aqueous solution of 3.0 mol / l lithium hydroxide in an amount corresponding to 1.05 was dropped and reacted, spray drying was performed. The obtained dried product was placed in an alumina boat and calcined in an oxygen atmosphere at 750 ° C. for 5 hours in a tubular furnace to obtain LiNi _0.4 Mn.
_0.6 O ₂ powder was obtained.

Comparative Example 11 1.0 m so that the molar ratio of Co / (Ni + Co) = 0.6.
ol / l of a mixed aqueous solution of cobalt nitrate and nickel nitrate is prepared, and the mixed aqueous solution and a 1.0 mol / l aqueous solution of sodium hydroxide are simultaneously added so as to have a pH of 8.5, and strongly stirred at a temperature of 25 ° C. The reaction mixture was filtered, washed with water, and suspended in water to give 1 mol / l of Ni _0.4 Co _0.6 (OH) _1.7 (NO ₃ ) _0.3.
A slurry was obtained. The atomic ratio of this slurry to Ni is L
i / (Ni + Co) = 1.05 = 3.0m
ol / l aqueous solution of lithium hydroxide was dropped and reacted.
Spray drying was performed. The obtained dried product was put in an alumina boat, calcined in an oxygen atmosphere at 750 ° C. for 5 hours in a tubular furnace, and crushed in a mortar to obtain LiNi _0.4 Co _0.6 O ₂ powder.

Comparative Example 12 1.05 mol of lithium hydroxide, 0.9 mol of nickel hydroxide and 0.1 mol of aluminum hydroxide were thoroughly dry-mixed and pulverized in a mortar, and then 1000 kg using a Brinell hardness tester.
Press molding was performed at a static pressure of / cm ² . The molded product is placed in an alumina boat and placed in a tubular furnace in an oxygen atmosphere for 75 minutes.
Baking at 0 ° C. for 20 hours, leaving to cool, crushing and LiNi _0.9
An Al _0.1 O ₂ powder was obtained.

Comparative Example 13 1.05 mol of lithium hydroxide, 0.9 mol of nickel hydroxide and 0.1 mol of iron oxide were thoroughly dry-mixed and pulverized in a mortar, and then subjected to a static pressure of 1000 kg / cm ² using a Brinell hardness tester. Press molding was performed at a target pressure. The molded product was placed in an alumina boat, fired at 750 ° C. for 20 hours in an oxygen atmosphere in a tubular furnace, allowed to cool, and then crushed to obtain LiNi _0.9 Fe _0.1 O ₂ powder.

Comparative Example 14 1.05 mol of lithium hydroxide, 0.9 mol of nickel hydroxide and 0.1 mol of manganese dioxide were thoroughly dry-mixed and pulverized in a mortar, and then subjected to 1000 kg / c using a Brinell hardness tester.
Press molding was performed at a static pressure of m ² . The molded product is placed in an alumina boat and placed in a tube furnace in an oxygen atmosphere at 750 ° C.
For 20 hours, allowed to cool, then crushed to obtain LiNi _0.9 Mn
_0.1 O ₂ powder was obtained.

Comparative Example 15 1.05 mol of lithium hydroxide, 0.9 mol of nickel hydroxide and 0.1 mol of cobalt hydroxide were thoroughly dry-mixed and pulverized in a mortar, and then subjected to 1000 kg / c using a Brinell hardness tester.
Press molding was performed at a static pressure of m ² . The molded product is placed in an alumina boat and placed in a tube furnace in an oxygen atmosphere at 750 ° C.
For 20 hours, allowed to cool, and then crushed to obtain LiNi _0.9 Co
_0.1 O ₂ powder was obtained.

X-ray peak ratios (003) / (104), (006) / (104) of X-rays obtained from X-ray analysis diagrams of the composite oxides obtained in Examples 1 to 22 and Comparative Examples 1 to 15 described above. ,
Tables 1 and 2 show the BET specific surface area, the ratio of Ni ³⁺ , the average diameter of the secondary particles measured by a laser microtrack, and the long diameter of the primary particles obtained from the SEM photograph.

[0126]

[Table 1]

[0127]

[Table 2]

The basic metal salt (II) used in the wet method
Table 3 shows the primary particle size.

[0129]

[Table 3]

Incidentally, the major particle diameters of the composite oxides fired by spray drying were all in the range of 0.2 to 3.0 μm.

Test Method 1 Using the composite oxides obtained in Examples 1, 2, 6, and 14 and Comparative Examples 1, 2, 3, and 5, the following battery test (charge / discharge test) was performed.

In the positive electrode material, the lithium nickel composite oxide obtained in each of the above examples and a conductive binder (polytetrafluoroethylene-acetylene black) were mixed at a weight ratio of 2: 1. 0.5mm thick, 1 diameter
It was formed into an 8 mm pellet. This was pressed with a press machine at a pressure of 1 t / cm ² of stainless steel press band mesh to obtain a positive electrode mixture molded product.

As the negative electrode material, a lithium metal sheet punched out to a diameter of 18 mm was used. Put the positive electrode mixture molding in a stainless steel coin cell, 1 mol / l
Of LiPF ₆ in propylene carbonate: ethylene carbonate (1: 4 weight ratio) was injected in an appropriate amount. A separator and a negative electrode agent were placed thereon, and the negative electrode case was swaged to obtain a test lithium secondary battery. These fabrications were all performed under an argon atmosphere.
The performance of the positive electrode active material was evaluated by charging / discharging the obtained lithium secondary battery and examining the initial charge capacity and the decrease in discharge capacity due to repeated charge / discharge. The charge and discharge were performed at a constant current of 1 mA and a voltage regulation between 3.0 and 4.3 V.

The result of this battery test [initial discharge capacity (mA)
h / g), the 100th discharge capacity (mAh / g) and 1
The decay rate (%) of the 00th discharge capacity] was as shown in Tables 4 and 5.

[0135]

[Table 4]

[0136]

[Table 5]

Test Method 2 The following battery test (charge / discharge test) was performed using the composite oxides of Examples 1 to 22 and Comparative Examples 1 to 15.

The cathode material was 88% by weight of the lithium nickel composite oxide obtained in each of the above Examples and Comparative Examples, 6.0% by weight of acetylene black as a conductive agent, and 6.0% of tetrafluoroethylene as a binder. The mixture was mixed at a mixing ratio of% by weight, and then compression molded on a stainless steel mesh to obtain a pellet having a thickness of 5 mm and a diameter of 18 mm. The obtained pellet was dried at 200 ° C. for 2 hours to obtain a positive electrode material.

As the negative electrode material, a rolled lithium metal sheet pressed on a stainless steel substrate was used, and as the diaphragm, a porous film made of polypropylene (trade name “Celgard 2502”,
Hoechst Japan Co., Ltd.) and glass filter paper.

In the electrolyte, ethylene carbonate / dimethylmethoxyethane (1: 1) in which 1M LiClO ₄ was dissolved was used.
(1 weight ratio), from the assembly of the test cell (semi-open type cell) to the finishing, was performed in a dry box in which argon was replaced. This lithium battery was charged and discharged at a constant current density of 0.4 mA / cm ² between 3.0 and 4.3 V.

The results of this battery test [initial discharge capacity (mA)
h / g), the 100th discharge capacity (mAh / g) and 1
The decay rate (%) of the 00th discharge capacity] was as shown in Tables 6 and 7.

[0142]

[Table 6]

[0143]

[Table 7]

Test Method 3 As an indicator of the stability of the composite oxide obtained in the present invention at high temperatures, the exothermic reaction temperature of the positive electrode material after charging was measured by the following method.

Using the test cell prepared in Test Method 2, the positive electrode after charging was subjected to thermal analysis by DSC ("THERMOFLEX TAS200" manufactured by Rigaku Corporation) under an inert gas, and the exothermic reaction temperature was measured.

As a result, in Comparative Example 1, 208.0 ° C., in Example 15, 224.3 ° C., and in Example 20, 237.6 ° C.
An exothermic peak was observed at ° C.

When Co or the like is added to LiNiO ₂ , an increase in the temperature of the exothermic peak is observed. Further, even if the composition is the same, the positive electrode material having a large primary particle has a higher exothermic peak temperature, and the stability at high temperatures is enhanced. I understand.

[0148]

As described above, according to the present invention, Li _y-x1 Ni _1-x2 M _x O ₂ (where M is selected from the group consisting of Al, Fe, Co, Mn and Mg) represents one, indicates _{x = x 1 + x 2,} x 1
Is 0 ≦ x ₁ <0.2, x ₂ is 0 <x ₂ ≦ 0.5, and x is 0 <
x ≦ 0.5 and y is 0.9 ≦ y ≦ 1.3), wherein the crystal is sufficiently developed and the purity is high. A positive electrode active material for a secondary battery having excellent discharge capacity stability can be provided.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of the composite oxide obtained in Example 1 (X
RD).

FIG. 2 is an SEM photograph (1) of the composite oxide obtained in Example 1.
50 times).

FIG. 3 is an SEM photograph (3) of the composite oxide obtained in Example 1.
0000 times).

FIG. 4 is a particle size distribution of the composite oxide obtained in Example 1.

FIG. 5 is an XRD of the composite oxide obtained in Example 5.

FIG. 6 is an SEM photograph (1) of the composite oxide obtained in Example 5.
0000 times).

7 is an XRD of the composite oxide obtained in Example 6. FIG.

FIG. 8 is an SEM photograph (1) of the composite oxide obtained in Example 6.
50 times).

FIG. 9 is an SEM photograph (3) of the composite oxide obtained in Example 6.
0000 times).

FIG. 10 is a particle size distribution of the composite oxide obtained in Example 6.

FIG. 11 is an XRD of the composite oxide obtained in Example 9.

FIG. 12 is a SEM photograph (× 10000) of the composite oxide obtained in Example 9.

FIG. 13 is an XRD of the composite oxide obtained in Example 10.

FIG. 14 is a SEM photograph (30000 times) of the composite oxide obtained in Example 10.

FIG. 15 is a particle size distribution of the composite oxide obtained in Example 10.

FIG. 16 is an XRD of the composite oxide obtained in Example 13.

FIG. 17 is a SEM photograph (× 10000) of the composite oxide obtained in Example 13.

FIG. 18 is an XRD of the composite oxide obtained in Example 14.

FIG. 19 is an SEM photograph (× 150) of the composite oxide obtained in Example 14.

FIG. 20 is an SEM photograph (× 10000) of the composite oxide obtained in Example 14.

FIG. 21 is a particle size distribution of the composite oxide obtained in Example 14.

FIG. 22 is an XRD of the composite oxide obtained in Example 16.

FIG. 23 is a SEM photograph (× 1000) of the composite oxide obtained in Example 16.

FIG. 24 is an SEM photograph (× 10000) of the composite oxide obtained in Example 16.

FIG. 25 is a particle size distribution of the composite oxide obtained in Example 16.

FIG. 26 is an XRD of the composite oxide obtained in Example 19.

FIG. 27 is a SEM photograph (× 10000) of the composite oxide obtained in Example 19.

FIG. 28 is an XRD of the composite oxide obtained in Example 21.

FIG. 29 is an SEM photograph (× 50) of the composite oxide obtained in Example 21.

FIG. 30 is an SEM photograph (30000 times) of the composite oxide obtained in Example 21.

FIG. 31 shows a particle size distribution of the composite oxide obtained in Example 21.

FIG. 32 is an XRD of the composite oxide obtained in Comparative Example 1.

FIG. 33 is an SEM photograph (× 1000) of the composite oxide obtained in Comparative Example 1.

FIG. 34 is an SEM photograph (10000 times) of the composite oxide obtained in Comparative Example 1.

FIG. 35 shows a particle size distribution of the composite oxide obtained in Comparative Example 1.

36 is an XRD of the composite oxide obtained in Comparative Example 5. FIG.

FIG. 37 is a SEM photograph (3500 times) of the composite oxide obtained in Comparative Example 5.

FIG. 38 is an SEM photograph (10000 times) of the composite oxide obtained in Comparative Example 5.

FIG. 39 is an XRD of the composite oxide obtained in Comparative Example 15.

FIG. 40 is an SEM photograph (× 20000) of the composite oxide obtained in Comparative Example 15.

Continuation of the front page (31) Priority claim number Japanese Patent Application No. 8-148147 (32) Priority date May 17, 1996 (May 17, 1996) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 8-150127 (32) Priority date May 21, 1996 (May 21, 1996) (33) Priority claim country Japan (JP) (31) Priority claim number 8-181587 (32) Priority date June 20, 1996 (June 20, 1996) (33) Priority claiming country Japan (JP) (72) Inventor Kazumi Fujimori Yokohoonji 55, Kamiichi-cho, Kamiichi-gun, Nakashinkawa-gun, Toyama Address Fuji Chemical Industry Co., Ltd. (72) Inventor town Tamaki 55, Yokohoonji, Kamiichi-cho, Nakashinagawa-gun, Toyama Prefecture Fuji Chemical Industry Co., Ltd. (56) References JP-A-6-96768 (JP, A) JP-A Heisei 5-283076 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01G 53/00 H01M 4/36-4/62 H01M 10/40

Claims (7)

(57) [Claims] 1. A general formula (I) Li _y-x1 Ni _1-x2 M _x O ₂ (I) wherein M is 1 selected from the group consisting of Al, Fe, Co, Mn and Mg. Species, x = x ₁ + x ₂ (where (i) when M is Al or Fe, 0 <x ≦ 0.2
Where x ₁ is 0, x ₂ is x, (ii) when M is Co or Mn, 0 <x ≦ 0.5, x ₁ is 0, x ₂ is x, iii) when M is Mg, 0 <x ≦ 0.2;
x ₁ is 0 <x ₁ <0.2, x ₂ is 0 <shows the x ₂ <0.2), y is indicated by 'showing a 0.9 ≦ y ≦ 1.3, the X-ray diffraction (003) plane and (1) at Miller index hkl
The diffraction peak ratio (003) / (104) on the (04) plane is 1.2 or more, the diffraction peak ratio (006) / (101) on the (006) and (101) planes is 0.13 or less, BET
A surface area of 0.1 to ² m ² / g, a ratio of Ni ^{3+ to} all Ni of 99% by weight or more, an average particle diameter D of 5 to 100 μm,
10% of the particle size distribution is 0.5D or more, 90% is 2D or less,
Observed by a scanning electron microscope (SEM), the particles are spherical secondary particles having irregularities on the surface. The primary particle diameter of the spherical secondary particles has a major particle diameter of 0.2 as observed by SEM. ~ 3.
A lithium-nickel composite oxide comprising uniform particles distributed in a range of 0 μm and having an average major particle diameter of 0.3 to 2.0 μm. Wherein formula ^{_{(II) Ni 1-x M}} p x (OH) 2-nz (A n-)
_{[Z + (px−2x) / n]} · mH ₂ O (II) (wherein, M represents one kind selected from the group consisting of Al, Fe, Co, Mn and Mg, and p represents M 2 ≦
indicates p ≦ ^{3, A n-} is an n-valent anion, x, z and m
Are 0 <x ≦ 0.2, 0.03 ≦ z ≦ 0.3, 0
≦ m <2, a basic metal salt represented by the following formula) and a water-soluble lithium compound in an aqueous medium:
The reaction is performed under the condition that the molar ratio of Li / (Ni + M) is 0.9 to 1.3, and the obtained slurry is spray-dried and then fired in an oxidizing atmosphere at about 600 ° C. to 900 ° C. for about 4 hours or more The method for producing a lithium nickel composite oxide according to claim 1, wherein 3. A general formula (I) Li _y-x1 Ni _1-x2 M _x O ₂ (I) wherein M is 1 selected from the group consisting of Al, Fe, Co, Mn and Mg. X = x ₁ + x ₂ (where (i) when M is Al or Fe, 0 <x ≦ 0.2
Where x ₁ is 0, x ₂ is x, (ii) when M is Co or Mn, 0 <x ≦ 0.5, x ₁ is 0, x ₂ is x, iii) when M is Mg, 0 <x ≦ 0.2;
x ₁ is represented by _{0 <x 1 <0.2, x} 2 represents the _{0 <x 2 <0.2),} y represents a 0.9 ≦ y ≦ 1.3], the X-ray diffraction mirror Diffraction peak ratio at (003) and (104) planes at index hkl (003) / (104)
Is not less than 1.2, the diffraction peak ratio (006) / (101) on the (006) plane and the (101) plane is not more than 0.13, and S
A lithium-nickel composite oxide, wherein the average major axis of primary particles observed by EM is 1 to 10 μm. Wherein said general formula _{(II) Ni 1-x M} p x (OH) 2-nz (A n-) [z + (px-2x) / n] · mH 2 O (II) ( wherein, M represents one kind selected from the group consisting of Al, Fe, Co, Mn and Mg, p represents the valence of M, and 2 ≦ p
≦ 3, A ⁿ⁻ is an n-valent anion, x, z and m are positive numbers satisfying the ranges of 0 <x ≦ 0.2, 0.03 ≦ z ≦ 0.3 and 0 ≦ m <2, respectively. ) And a water-soluble lithium compound in an aqueous medium, Li / (Ni
+ M) is reacted under the condition that the molar ratio is 0.9 to 1.3, the obtained slurry is spray-dried, and the spray-dried product is press-molded, and then at 600 ° C to 900 ° C in an oxidizing atmosphere for about 4 hours. 4. The method for producing a lithium nickel composite oxide according to claim 3, wherein the firing is performed. 5. The general formula _{(II) Ni 1-x M} p x (OH) 2-nz (A n-) [z + (px-2x) / n] · mH 2 O (II) ( wherein, M Represents one selected from the group consisting of Al, Fe, Co, Mn and Mg, p represents the valence of M, and 2 ≦ p
≦ 3, A ⁿ⁻ is an n-valent anion, x, z and m are positive numbers satisfying the ranges of 0 <x ≦ 0.2, 0.03 ≦ z ≦ 0.3 and 0 ≦ m <2, respectively. In a water medium, a basic metal salt represented by｝ and a water-soluble lithium compound are Li / (Ni
+ M) is reacted under the condition that the molar ratio is 0.9 to 1.3, the obtained slurry is spray-dried, and the spray-dried product is directly used at 600 ° C to 900 ° C in an oxidizing atmosphere for about 0.5 hour or more. Firing, then pulverize the obtained fired product, press molding,
4. The method for producing a lithium nickel composite oxide according to claim 3, further comprising re-firing at 600 to 900 [deg.] C. in an oxidizing atmosphere for about 1 hour or more. 6. A positive electrode active material for a secondary battery, comprising the lithium nickel composite oxide according to claim 1 or 3 as an active ingredient. 7. The positive electrode active material for a lithium secondary battery according to claim 6, wherein the decay rate of the discharge capacity at the 100th cycle is 10% or less.