JP2009215143A - Manufacturing method of planar lithium nickel composite oxide and planar lithium nickel composite oxide using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar lithium nickel composite oxide capable of obtaining a secondary battery having high safety and good cycling characteristic when used as a positive electrode active material for a lithium ion secondary battery and to provide its manufacturing method. <P>SOLUTION: In the manufacturing method of the planar lithium nickel composite oxide whose composition is represented by a following formula (1): Li<SB>y</SB>Ni<SB>1-x</SB>M<SB>x</SB>O<SB>2</SB>(wherein, M is at least one kind element selected among a transition metal other than Ni, an alkaline earth metal element, Al, Ti, Ga, In or Si, x is 0≤x≤0.3 and y is 0.95≤y≤1.1), following steps (1)-(3) are included. (1) A planar nickel hydroxide having 3-20 μm plane direction particle size and 50-150 m<SP>2</SP>/g specific surface area is prepared. (2) A lithium compound is added to the planar nickel hydroxide and mixed. (3) An obtained mixture is burned at 650-850°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a plate-like lithium nickel composite oxide and a plate-like lithium nickel composite oxide using the same, and more specifically, when used as a positive electrode active material for a lithium ion secondary battery, the safety is high. The present invention relates to a plate-like lithium nickel composite oxide capable of obtaining a secondary battery with good cycle characteristics and a method for producing the same.

  Conventionally, lithium ion secondary batteries mainly use a lithium cobalt composite oxide as a positive electrode active material, and have greatly expanded their market. However, in recent years, the capacity of the lithium cobalt composite oxide has reached the limit capacity, and it is difficult to use it for higher power electronic devices required for future video, music, communication, etc. The situation has been reached. Therefore, a new high-capacity lithium ion secondary battery has been developed as a positive electrode active material, which is switched from a conventional lithium cobalt composite oxide to a lithium-nickel composite oxide capable of obtaining a higher capacity.

  By the way, since a flammable organic electrolyte is used for a lithium ion secondary battery, when the battery temperature rises for some reason, this triggers heat generation, and then falls into a vicious cycle of fire or explosion. Therefore, conventionally, a safety mechanism that suppresses self-heating is provided. However, when the above lithium nickel composite oxide is used as the positive electrode active material, considering only the active material in the positive electrode material from a microscopic viewpoint, a part of it decomposes when overcharged or at a high temperature in a charged state, and oxygen is removed. It has the disadvantage of generating and creating a factor of heat generation. Therefore, from the viewpoint of suppression of heat generation, the lithium nickel composite oxide preferably has large primary particles and excellent crystallinity.

When producing a lithium nickel composite oxide used as a positive electrode active material for such a high-capacity lithium ion secondary battery, the following method may be mentioned as a method for producing nickel hydroxide as a raw material.
For example, a method in which ammonia is added to an aqueous nickel salt solution to form a nickel-ammonia complex salt, and then caustic is added to generate nickel hydroxide (see, for example, Patent Document 1), an aqueous nickel salt solution, In the method of taking out nickel hydroxide by performing continuous neutralization in the same tank using caustic alkali (for example, refer to Patent Document 2), the method of taking out nickel hydroxide by carrying out continuous neutralization, and continuous ammonia. A method of adding (for example, see Patent Document 3) is disclosed.

  However, nickel hydroxide obtained by these methods is a spherical or similar elliptical secondary particle in which fine primary particles are aggregated. Although such an aggregate has a large particle size, it constitutes this. The primary particles had a small particle size. That is, all of the conventional nickel hydroxides consisted of particles with low crystallinity. Therefore, as the lithium nickel composite oxide obtained using such nickel hydroxide, the shape of the nickel hydroxide particles used as a raw material, although there is some growth of primary particles depending on the atmosphere and firing conditions in the production process In general, the shape is spherical or elliptical secondary particles composed of fine particles having a particle size of 1 μm or less or submicron or less. That is, it was difficult to obtain particles having a large primary particle size of 1 μm or more with the lithium nickel composite oxide obtained using nickel hydroxide by the above production method.

  As another method for producing nickel hydroxide, there is a method for producing primary particle-dispersed particles that are small particles whose major axis direction is as small as about 1 μm but are not secondary particles (see, for example, Patent Document 4). Proposed. However, even if lithium nickel composite oxide is synthesized using nickel hydroxide obtained by this method as a raw material, the primary particles are small and the crystallinity is low. high.

Furthermore, in the lithium ion secondary battery, the crystal lattice of the lithium nickel composite oxide, which is the positive electrode active material, repeatedly expands and contracts during charge and discharge, and in this process, the active material is pulverized and the capacity is reduced. However, it is known that this pulverization is also more likely to occur with a positive electrode active material with smaller primary particles (see, for example, Patent Documents 5 and 6).
As an improvement measure, new nickel hydroxide having a primary particle average major axis diameter of 1 to 50 μm (for example, see Patent Document 7) is disclosed. However, the battery characteristics are not disclosed, and it is unclear whether safety and high capacity are compatible. Moreover, in the manufacturing method, the material which consists of alkali hydroxide, ammonia, and ammonium salt other than the nickel base material used as a raw material is heated at the temperature of 120-350 degreeC. Therefore, since the manufacturing method uses many materials, the raw material cost is high, and since a highly volatile substance such as ammonia is used, it is necessary to use an autoclave. There are many difficult points to supply to the market, such as being unsuitable.

JP 56-143671 A (first page) JP 63-16555 A (1st page) Japanese Patent Laid-Open No. 2-6340 (first page) JP-A-11-246226 (first page, second page) JP-A-5-151998 (first page, second page) JP-A-8-69790 (first page, second page) JP 11-1324 A (first page, second page)

  An object of the present invention is to provide a plate-like lithium nickel composite that can provide a secondary battery with high safety and good cycle characteristics when used as a positive electrode active material for a lithium ion secondary battery in view of the above-mentioned problems of the prior art. It is to provide an oxide and a method for manufacturing the oxide.

  In order to achieve the above object, the present inventors have conducted extensive research on lithium nickel composite oxides. As a result, the lithium nickel composite oxides have a specific composition and have a specific planar particle size and ratio. When a plate-like nickel hydroxide having a surface area and a lithium compound are mixed and baked at a specific temperature, when used as a positive electrode active material for a lithium ion secondary battery, both the safety and high capacity of the secondary battery are achieved. A plate-like lithium nickel composite oxide having a special porous structure with large primary particles and excellent crystallinity can be obtained, and the plate-like nickel hydroxide has a specific amount of alkali metal hydroxide. As a result, it was found that a product obtained by heating and reacting nickel hydroxide was suitable, and the present invention was completed.

That is, according to the first aspect of the present invention, there is provided a method for producing a plate-like lithium nickel composite oxide having a composition represented by the following formula (1):
Equation _{(1): Li y Ni 1} -x M x O 2
(In the formula, M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si, and x is 0 ≦ x ≦ 0.3. And y is 0.95 ≦ y ≦ 1.1.)
A method for producing a plate-like lithium nickel composite oxide comprising the following steps (1) to (3) is provided.
(1) A plate-like nickel hydroxide having a planar particle size of 3 to 20 μm and a specific surface area of 50 to 150 m ² / g is prepared.
(2) A lithium compound is added to the plate-like nickel hydroxide and mixed.
(3) The obtained mixture is fired at a temperature of 650 to 850 ° C.

  According to a second aspect of the present invention, there is provided the plate-like lithium nickel composite oxide according to the first aspect, wherein the thickness of the plate-like nickel hydroxide is 1 to 8 μm. A manufacturing method is provided.

According to a third aspect of the present invention, in the first or second aspect, the composition of the plate-like nickel hydroxide is represented by the following formula (2). A method for producing a plate-like lithium nickel composite oxide is provided.
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)

  According to a fourth invention of the present invention, in any one of the first to third inventions, the plate-like nickel hydroxide contains an alkali metal hydroxide at a molar ratio of 0.5 to the nickel hydroxide. Plate-like lithium produced by suspending nickel hydroxide in an aqueous solution containing at least twice the ratio and stirring the aqueous solution while maintaining the temperature at 90 to 190 ° C A method for producing a nickel composite oxide is provided.

  According to a fifth aspect of the present invention, in the fourth aspect, the alkali metal hydroxide is at least one selected from sodium hydroxide, potassium hydroxide, or lithium hydroxide. A method for producing a plate-like lithium nickel composite oxide is provided.

  According to a sixth aspect of the present invention, in the fourth or fifth aspect, the inorganic chloride is further contained in the aqueous solution, and the amount of chlorine contained in the inorganic chloride is relative to nickel hydroxide. Provided is a method for producing a plate-like lithium nickel composite oxide, which is contained so as to have a molar ratio of 0.01 to 0.20.

  According to a seventh aspect of the present invention, in the sixth aspect, the inorganic chloride is at least one selected from alkali metal chloride, alkaline earth metal chloride, or nickel chloride. A method for producing a plate-like lithium nickel composite oxide is provided.

According to an eighth aspect of the present invention, in the sixth aspect, the composition of the nickel hydroxide is represented by the following formula (2), and the inorganic chloride is: There is provided a method for producing a plate-like lithium nickel composite oxide, which is at least one chloride of a transition metal used as M in Formula (2).
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)

  According to a ninth invention of the present invention, in any one of the first to eighth inventions, in the step (2), x in the formula (1) is further added to the plate-like nickel hydroxide. Provided is a method for producing a plate-like lithium nickel composite oxide, wherein aluminum hydroxide or aluminum oxide is added so that 0 <x ≦ 0.3.

  According to a tenth aspect of the present invention, in the ninth aspect, the plate-like lithium nickel composite oxide is characterized in that the aluminum hydroxide or the aluminum oxide coats the particle surface of the plate-like nickel hydroxide. A method of manufacturing an article is provided.

According to the eleventh aspect of the present invention, in any one of the first to tenth aspects, the following steps (2-1) and (2-2) are included instead of the step (2). A method for producing a plate-like lithium nickel composite oxide is provided.
(2-1) The plate-like nickel hydroxide is roasted at a temperature of 400 ° C. to 900 ° C. to obtain plate-like nickel oxide.
(2-2) A lithium compound is added to the plate-like nickel oxide and mixed.

  According to a twelfth aspect of the present invention, in the eleventh aspect, in the step (2-2), x in the formula (1) is further set to 0 <x in the plate-like nickel oxide. Provided is a method for producing a plate-like lithium nickel composite oxide, wherein aluminum hydroxide or aluminum oxide is added so as to satisfy ≦ 0.3.

  According to a thirteenth aspect of the present invention, in the twelfth aspect, the plate-like lithium nickel composite oxide characterized in that the aluminum hydroxide or the aluminum oxide covers the surface of the plate-like nickel oxide particles. A manufacturing method is provided.

  According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the lithium compound is at least one selected from lithium hydroxide, oxide, chloride, carbonate, or nitrate. There is provided a method for producing a plate-like lithium nickel composite oxide characterized by being a seed.

According to the fifteenth aspect of the present invention, there is provided a plate-like lithium nickel composite oxide obtained by the method for producing a plate-like lithium nickel composite oxide of the first to fourteenth inventions,
A plate-like lithium nickel composite oxide having a planar particle size of 3 to 20 μm and a porous structure is provided.

  According to a sixteenth aspect of the present invention, in the fifteenth aspect, there is further provided a plate-like lithium nickel composite oxide characterized in that the thickness is 1 to 8 μm.

  According to the method for producing a plate-like lithium nickel composite oxide of the present invention and the plate-like lithium nickel composite oxide using the same, when a lithium ion secondary battery is used as a positive electrode active material without requiring a special device. Since a new plate-like lithium nickel composite oxide having a special porous structure with large primary particles and excellent crystallinity can be obtained, which can achieve both safety and high capacity of the secondary battery, its industrial The value is extremely great.

Hereinafter, the manufacturing method of the plate-like lithium nickel composite oxide of the present invention and the plate-like lithium nickel composite oxide using the same will be described in detail.
1. Method for producing plate-like lithium nickel composite oxide The method for producing a plate-like lithium nickel composite oxide of the present invention is a method for producing a plate-like lithium nickel composite oxide whose composition is represented by the following formula (1). ,
Equation _{(1): Li y Ni 1} -x M x O 2
(In the formula, M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si, and x is 0 ≦ x ≦ 0.3. And y is 0.95 ≦ y ≦ 1.1.)
It includes the following steps (1) to (3).
(1) A plate-like nickel hydroxide having a planar particle size of 3 to 20 μm and a specific surface area of 50 to 150 m ² / g is prepared.
(2) A lithium compound is added to the plate-like nickel hydroxide and mixed.
(3) The obtained mixture is fired at a temperature of 650 to 850 ° C.

In the method for producing the plate-like lithium nickel composite oxide, it is particularly important to prepare plate-like nickel hydroxide having a specific surface area of 50 to 150 m ² / g. That is, plate lithium nickel having a special porous structure with large primary particles and excellent crystallinity by firing a mixture of plate nickel hydroxide having a specific surface area of 50 to 150 m ² / g and a lithium compound. A composite oxide is obtained.

The “special porous structure” which is one of the major features of the plate-like lithium nickel composite oxide of the present invention is a fibrous or dendritic structure having a maximum microstructure of 0.2 to 2 μm as described later. Alternatively, it means a structure having a form in which branch-shaped primary particles are entangled to form secondary particles, and there are many voids continuously connected to the outside of the secondary particles between the primary particles. The details of the process by which such a special porous structure is formed are unknown, but are thought to be formed by the following mechanism.
That is, when a mixture of plate-like nickel hydroxide having a large specific surface area of 50 to 150 m ² / g and a lithium compound is fired, the lithium compound melted during firing is fine on the particle surface of the plate-like nickel hydroxide. It reacts with nickel hydroxide in the pore and penetrates into the plate-like nickel hydroxide particles while forming a lithium nickel composite oxide. Further, the formation of the lithium nickel composite oxide in the permeated portion proceeds to form a non-uniform and partial lithium nickel composite oxide inside the plate-like nickel hydroxide particles. Here, rather than being uniformly formed from the outer surface to the inside, it is considered that the above-described special porous structure is formed by the formation of this non-uniform and partial lithium nickel composite oxide. .

  In general, when a mixture of nickel hydroxide and a lithium compound is fired, the nickel hydroxide remains strongly after firing. Therefore, also in the manufacturing method described above, by controlling the shape and size of the plate-like nickel hydroxide to a predetermined value, a plate-like lithium nickel composite oxide having a desired planar particle size and thickness can be obtained. .

Below, the said manufacturing method is demonstrated in detail for every process.
Step (1) The step (1) is a step of preparing plate-like nickel hydroxide having a planar particle size of 3 to 20 μm and a specific surface area of 50 to 150 m ² / g.
Here, the plate-like nickel hydroxide is prepared because, as described above, when the mixture of nickel hydroxide and the lithium compound is fired, the nickel hydroxide remains strongly after firing. This is because a plate-like lithium nickel composite oxide can be obtained by using nickel hydroxide. In addition, since it has a plate-like shape, a permeation effect due to the molten lithium compound by the above-described mechanism is likely to occur, thereby forming a special porous structure.

The specific surface area of the plate-like nickel hydroxide is 50 to 150 m ² / g. That is, when the specific surface area is less than 50 m ² / g, the plate-like lithium nickel composite oxide does not form a porous structure. On the other hand, when the specific surface area exceeds 150 m ² / g, the primary particles forming the porous structure become too fine, and thus the safety becomes insufficient when used as the positive electrode active material.
The planar nickel hydroxide has a grain size in the plane direction of 3 to 20 μm. In addition, a plane direction particle size means the largest diameter in the plane of the particle | grains of plate-like nickel hydroxide. That is, by setting the grain size in the plane direction to 3 to 20 μm, the grain size in the plane direction of the obtained plate-like lithium nickel composite oxide can be set to 3 to 20 μm suitable as the positive electrode material.

  Furthermore, although it does not specifically limit as thickness of the said plate-like nickel hydroxide, It is preferable that it is 1-8 micrometers. That is, when the thickness is less than 1 μm or exceeds 8 μm, the thickness of the obtained plate-like lithium nickel composite oxide may not be 1 to 8 μm suitable as the positive electrode material.

The composition of the plate-like nickel hydroxide is not particularly limited, but in order to improve the battery characteristics when the plate-like lithium nickel composite oxide obtained using this is used as a positive electrode active material, It is preferable that it is what is represented by following formula (2).
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)

The method for producing the plate-like nickel hydroxide is not particularly limited, but in an aqueous solution containing an alkali metal hydroxide at a molar ratio of 0.5 times or more with respect to nickel hydroxide. A method in which nickel hydroxide is suspended and stirred while maintaining the temperature of the aqueous solution at 90 to 190 ° C is preferred. As a result, plate-like nickel hydroxide having a planar particle size of 3 to 20 μm and a specific surface area of 50 to 150 m ² / g is obtained.

  Here, the aqueous solution used in the method for producing the plate-like nickel hydroxide is preferably an alkali metal hydroxide in a molar ratio of 0.5 times or more with respect to nickel hydroxide, preferably 2.5 to 10 times is more preferable. That is, since the alkali metal hydroxide acts to increase the particle size in the planar direction, when the content ratio of the alkali metal hydroxide is less than 0.5 times in molar ratio with respect to nickel hydroxide, Crystal dissolution and reprecipitation of nickel oxide cannot be sufficiently performed, causing nonuniformity and deficiency, and the average particle size in the plane direction may be less than 3 μm. On the other hand, the alkali metal hydroxide has a higher concentration, but if the molar ratio exceeds 10 times, the improvement in the effect cannot be expected and it is merely wasted.

  The alkali metal hydroxide is not particularly limited, but is preferably at least one selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide, which is inexpensive and easily dissolved in water.

As said temperature, Preferably it is 90-190 degreeC, More preferably, it is 100-180 degreeC, More preferably, it is 140-180 degreeC. That is, by maintaining the temperature at 90 to 190 ° C., excess water evaporates, and nickel hydroxide crystallizes and reprecipitates in an aqueous solution of high-concentration alkali metal hydroxide. Is generated.
Here, when the temperature is lower than 90 ° C., the decay phenomenon or dissolution of the nickel hydroxide particles in the aqueous solution by the alkali metal hydroxide proceeds, but the nucleation during reprecipitation is more dominant than the crystal growth. It may not lead to sufficient growth in the direction. On the other hand, when the temperature exceeds 190 ° C., crystal growth proceeds excessively, the grain size in the plane direction exceeds 20 μm, and oxidation is likely to occur and the valence stability may be impaired.

  In the above aqueous solution, the amount of water that dissolves the alkali metal hydroxide is not particularly limited, and it is preferable to maintain a stirring slurry concentration after suspending nickel hydroxide. That is, if the amount of water is too large, it takes a lot of time to evaporate the water and the time to reach the reaction temperature becomes long, so the productivity is lacking. On the other hand, if there is too little water, it becomes clay after suspension, Since alkali metal hydroxide does not spread uniformly over the entire nickel hydroxide, non-uniform growth may occur.

  In the method for producing plate-like nickel hydroxide, if necessary, an inorganic chloride is added to the aqueous solution containing the alkali metal hydroxide, and the amount of chlorine contained in the inorganic chloride is changed to nickel hydroxide. It can be made to contain so that it may become a ratio of 0.01-0.20 time by the molar ratio with respect to this. That is, the thickness of the plate-like nickel hydroxide particles can be more easily controlled by including an inorganic chloride in the aqueous solution. Here, when the amount of chlorine is less than 0.01 times in molar ratio, there is almost no effect of increasing the thickness of the plate-like crystal, while when the amount of chlorine exceeds 0.2 times in molar ratio, the thickness is 8 μm. It is because it may exceed.

The inorganic chloride is not particularly limited and can be used as long as it is a water-soluble salt that does not contain an element that impedes battery performance. However, alkali metal chloride, alkaline earth metal chloride, nickel chloride can be used. Or at least one chloride selected from transition metal chlorides used as M in the formula (2) representing the composition of the plate-like nickel hydroxide.
Among these, the composition of nickel hydroxide is represented by the formula (2) representing the composition of the plate-like nickel hydroxide, and the inorganic chloride is represented by M in the formula (2). Preferably, the transition metal used is at least one chloride.

The nickel hydroxide can be used regardless of its shape, but preferably has a particle size of 100 μm or less in order to uniformly stir in an aqueous solution. For the purpose of improving battery performance, nickel hydroxide containing an additive element, for example, nickel hydroxide represented by the following formula (2) is preferably used.
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)

The reaction tank used in the method for producing the plate-like nickel hydroxide is not particularly limited, and it is sufficient if heating up to the holding temperature and stirring in the tank are possible. The mechanism is not necessary. Here, as time to hold | maintain at the said temperature, it does not specifically limit, What is necessary is just to judge with the magnitude | size of the produced | generated plate-shaped nickel hydroxide. That is, the retention may be terminated when the nickel hydroxide suspended as a raw material is consumed and the plate-like nickel hydroxide powder has grown to a desired size.
Then, after completion | finish of holding | maintenance, under normal conditions, it can wash with water, and also can dry and can obtain plate-like nickel hydroxide powder.

Steps (2), (2-1), (2-2) The step (2) is a step of adding and mixing a lithium compound to the plate-like nickel hydroxide prepared in the step (1). is there.
Moreover, it can replace with the process of said (2) and can include the process of the following (2-1) and (2-2) as needed.
(2-1) The plate-like nickel hydroxide is roasted at a temperature of 400 ° C. to 900 ° C. to obtain plate-like nickel oxide.
(2-2) A lithium compound is added to the plate-like nickel oxide and mixed.

  In the step (2-1), the plate-like nickel hydroxide is roasted at a temperature of 400 ° C. to 900 ° C. to obtain plate-like nickel oxide. Thereby, in baking after mixing with a lithium compound, the quantity of the water vapor | steam generated can be reduced and a plate-like lithium nickel composite oxide can be obtained stably. That is, when the roasting temperature is less than 400 ° C., the nickel valence of the plate-like nickel oxide is not stable, and the composition is not stable, so that the lithium nickel composite oxide aiming at a specific composition ratio cannot be synthesized. There is. On the other hand, when the roasting temperature exceeds 900 ° C., the crystallinity of nickel oxide becomes too high, a heterogeneous phase is generated when a lithium nickel composite oxide is synthesized, and the battery characteristics deteriorate when used as a positive electrode active material. There are things to do.

  Here, in the plate-like nickel hydroxide or plate-like nickel oxide, x described in the formula (1) representing the composition of the plate-like lithium nickel composite oxide is such that 0 <x ≦ 0.3. In addition, aluminum hydroxide or aluminum oxide can be added. Thereby, the safety | security of a battery when the obtained lithium nickel composite oxide is used as a positive electrode active material can be improved.

In addition, as a method of making the lithium nickel composite oxide contain aluminum, the following methods (a) to (c) are used. In the method for producing plate-like nickel hydroxide, aluminum should be uniformly contained. If difficult, it is preferable to mix a desired amount of aluminum hydroxide or aluminum oxide with plate-like nickel hydroxide or plate-like nickel oxide before firing. Furthermore, titanium can be contained in the lithium nickel composite oxide by using titanium oxide instead of aluminum hydroxide or aluminum oxide.
(A) Aluminum is dissolved in plate-like nickel hydroxide.
(B) A desired amount of aluminum hydroxide or aluminum oxide is mixed with plate-like nickel hydroxide or plate-like nickel oxide before firing.
(C) The aluminum hydroxide or aluminum oxide covers at least partially the surface of the plate-like nickel hydroxide or plate-like nickel oxide particles.

  Here, by mixing the plate-like nickel hydroxide and aluminum hydroxide or aluminum oxide before roasting, the plate-like nickel oxide obtained by roasting can be made to contain aluminum uniformly, and the subsequent firing Thus, it can be dissolved in a plate-like lithium nickel composite oxide. In addition, when aluminum hydroxide or aluminum oxide is mixed with the plate-like nickel oxide after roasting, it can be dissolved in the plate-like lithium nickel composite oxide by subsequent firing. Furthermore, when plate-like nickel hydroxide and aluminum hydroxide or aluminum oxide are mixed to directly produce a plate-like lithium nickel composite oxide, aluminum is solid-dissolved by firing.

  The mixing of the plate-like nickel hydroxide or plate-like nickel oxide with aluminum hydroxide or aluminum oxide is not particularly limited, but may include a dry blender such as a V blender, a Spartan luzer, or a vertical granulator. A mixing granulator can be used, and it is preferable to carry out within a suitable time range for uniform mixing. Here, as aluminum hydroxide or aluminum oxide, in order to promote the reaction, it is preferable to use finely pulverized aluminum hydroxide or aluminum oxide, and the particle diameter is preferably 0.01 to 1 μm.

Furthermore, in order to make each particle contain aluminum uniformly, it is preferable that the aluminum hydroxide or aluminum oxide covers the surface of the plate-like nickel hydroxide or plate-like nickel oxide.
Although it does not specifically limit as the method of coating | covering, The method of coat | covering the particle | grain surface of the said plate-like nickel hydroxide or plate-like nickel oxide at least partially is mentioned.
For example, first, plate-like nickel hydroxide or plate-like nickel oxide is suspended in water, and then sodium aluminate is added to a desired composition and dissolved by stirring. Next, sulfuric acid is further added to the slurry to neutralize it, so that aluminum hydroxide is deposited on the surface of the plate-like nickel hydroxide or plate-like nickel oxide.
Further, the surface of plate-like nickel hydroxide is coated with aluminum hydroxide or aluminum oxide by a mechanochemical method. When the mechanochemical method is used, it is preferable to finely pulverize aluminum hydroxide or aluminum oxide in the same manner as in the mixing described above.

  In the step (2) or (2-2), when the plate-like nickel hydroxide or plate-like nickel oxide and the lithium compound are mixed, the aluminum hydroxide or the aluminum oxide may be mixed at the same time. The mixing at this time is not particularly limited, but a dry mixer or a mixing granulator such as a V blender, a Spartan luzer, or a vertical granulator can be used. It is preferable to carry out in the range.

  The lithium compound used in the step (2) or (2-2) is not particularly limited, and is at least one selected from lithium hydroxide, oxide, chloride, carbonate, or nitrate. Of these, lithium hydroxide or oxide, which does not damage the furnace or mortar used in firing and has a low environmental load, is preferable.

Step (3) In the step (3), the mixture obtained in (2) or (2-2) is 650 to 850 ° C, preferably 680 to 800 ° C, more preferably 700 to 780 ° C. This is a step of baking at a temperature. Thereby, the plate-like lithium nickel composite oxide of the present invention is obtained. That is, when the firing temperature is less than 680 ° C., unreacted lithium compound remains, or the crystallinity of the obtained lithium nickel composite oxide is lowered and the battery performance is lowered. On the other hand, when the firing temperature exceeds 800 ° C., the lithium nickel composite oxide changes to a compound having a different structure or composition, and battery performance is significantly reduced.

  The atmosphere at the time of firing is not particularly limited, but is preferably a gas atmosphere having as little carbon dioxide or moisture as possible, for example, an atmosphere having an oxygen concentration of 70% by volume or more. That is, in the presence of carbon dioxide gas, lithium on the surface of the lithium nickel composite oxide produced after firing may be carbonated, resulting in internal resistance of the battery. In addition, if moisture is present, it is adsorbed on the dried particles after firing, and the adsorbed water reacts with the solvent at the time of electrode preparation to cause gelation, or oxygen and Hydrogen may be generated, causing a risk of explosion.

  The firing time is determined by firing conditions such as firing temperature and throughput, and is not particularly limited. However, firing is preferably performed for 10 hours or more, and firing for 20 hours or more. Is more preferable. That is, when the firing time is shorter than 10 hours, the time required for comprehensively such as dehydration process, reaction process, and crystal growth process may be insufficient.

  The furnace used for the firing is not particularly limited, and a furnace normally used for firing can be used. However, the mixture is filled in a ceramic or stainless steel bowl, and a box-type electric furnace or lifting furnace is used. In addition to a batch furnace such as an atmospheric furnace, a continuous furnace such as a roller hearth kiln or a pusher furnace is preferable.

The plate-like lithium nickel composite oxide after firing obtained in the step (3) is subjected to a pulverization treatment so as to obtain a desired particle size by mechanical pulverization such as a pin mill or a hammer mill, if necessary. Can do.
Thereafter, it is preferable to perform classification using a desired mesh screen so as not to cause protrusions due to lumps or coarse grains during electrode fabrication. As the sieve, an ultrasonic vibration sieve is preferable.
Subsequently, the plate-like lithium nickel composite oxide after classification is preferably heat-treated over time so that it can be sufficiently dehydrated in a vacuum dryer. In addition, after heat processing, it is preferable to cool in vacuum and to return to atmospheric pressure in dehydrated low dew point air.

2. Plate-like lithium nickel composite oxide The plate-like lithium nickel composite oxide of the present invention is a plate-like lithium nickel composite oxide obtained by the method for producing the plate-like lithium nickel composite oxide,
The grain size in the plane direction is 3 to 20 μm, and it has a porous structure.

The plate-like lithium nickel composite oxide has a composition represented by the following formula (1) and has a special porous structure with large primary particles and excellent crystallinity. It is particularly important to have a porous structure.
Equation _{(1): Li y Ni 1} -x M x O 2
(In the formula, M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si, and x is 0 ≦ x ≦ 0.3. And y is 0.95 ≦ y ≦ 1.1.)

The porous structure is a particle in which a plate-like nickel hydroxide plate-like shape (for example, hexagonal plate-like) remains as a raw material, and the microstructure is a fiber having a maximum diameter of 0.2 to 2 μm. , Dendritic or branch-shaped primary particles are intertwined to form secondary particles, and there are many voids continuously connected to the outside of the secondary particles between the primary particles, which will be described later In the example, it is a special porous structure as shown in a SEM (scanning electron microscope) photograph (FIGS. 2 and 3).
That is, by having this porous structure, when used as a positive electrode active material for a lithium ion secondary battery, the electrolyte enters into the secondary particles of the plate-like lithium nickel composite oxide, and the primary particles are equally lithium. Ion movement (intercalation) is performed. In addition, since there are a large number of voids, the expansion and contraction of the primary particles accompanying the movement of lithium ions are absorbed. By these effects, deterioration of the lithium nickel composite oxide due to the charge / discharge cycle is suppressed, and the cycle characteristics are improved.

Although it does not specifically limit as a specific surface area of the said plate-like lithium nickel complex oxide, It is preferable that it is 0.3-1.2 m < ² > / g. That is, the plate-like lithium-nickel composite oxide is formed from spherical or elliptical secondary particles obtained using nickel hydroxide obtained by a normal crystallization method as a raw material, despite having a porous structure. The specific surface area of the resulting lithium nickel composite oxide is excellent in crystallinity and means that there are few fine pores on the surface. As a result, since there are few fine pores, contact with the electrolytic solution is suppressed to a minimum, and since crystallinity is high, decomposition of the lithium nickel composite oxide and generation of oxygen are suppressed, and safety is improved. . Moreover, the high crystallinity also has the effect of suppressing the deterioration of the lithium nickel composite oxide due to the charge / discharge cycle and improving the cycle characteristics.

Here, when the specific surface area is less than 0.3 m ² / g, contact with the electrolytic solution is not sufficient, and a high-capacity battery cannot be obtained when used as a positive electrode active material. On the other hand, if the specific surface area exceeds 1.2 m ² / g, the crystallinity also decreases, and the effects of improving safety and cycle characteristics are not sufficient.

The particle size in the planar direction of the plate-like lithium nickel composite oxide is 3 to 20 μm. Thereby, when used as a positive electrode active material of a lithium ion secondary battery, both high safety and cycle characteristics can be achieved. In addition, a plane direction particle size means the maximum diameter in the plane of the particle | grains of lithium nickel complex oxide.
In other words, when the particle size in the plane direction is less than 3 μm, the particles are too fine during paste production, so that a large amount of solvent is required when applying to the electrode of the secondary battery, resulting in poor productivity and a very high specific surface area. Therefore, self-discharge and battery cycle deterioration are likely to occur. On the other hand, when the planar particle size exceeds 20 μm, the safety is improved, but the paste cannot be uniformly applied to the electrodes.

Furthermore, although it does not specifically limit as thickness of the said plate-like lithium nickel complex oxide, It is preferable that it is 1-8 micrometers. That is, when the thickness is less than 1 μm, the particles are easily broken and the cycle characteristics may be deteriorated. On the other hand, when the thickness exceeds 8 μm, the expansion and contraction of the primary particles accompanying the movement of lithium ions are not absorbed, and the cycle characteristics may be deteriorated.
The plate-like lithium nickel composite oxide has a composition represented by the above formula (1), and M in the formula is particularly preferably Co, Al, Ti, Ga, and 0 <x More preferably, ≦ 0.3, and even more preferably 0.005 ≦ x ≦ 0.3. By using M as these elements, when used as a positive electrode material active material of a secondary battery, a large improvement effect can be obtained due to safety and cycle characteristics.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the planar direction particle size and composition used in the examples and comparative examples, and the battery capacity after 25 cycles of the batteries obtained using the respective positive electrode active materials and the safety (thermal stability) evaluation method during charging Is as follows.
(1) Measurement of grain size and thickness in the plane direction: An average value of 50 particles arbitrarily selected in a SEM (scanning electron microscope) photograph was calculated.
(2) Composition analysis: ICP emission analysis was performed.
(3) Specific surface area: The specific surface area was measured by the BET one-point method using nitrogen gas adsorption.

(4) Evaluation of battery capacity after 25 cycles: A battery was produced using powder (active material) as follows, and the discharge capacity after 25 cycles was measured.
90% by mass of lithium nickel composite oxide (active material) was mixed with 5% by mass of acetylene black and 5% by mass of PVDF (polyvinylidene fluoride), and NMP (n-methylpyrrolidone) was added to make a paste. This was applied to a 20 μm thick aluminum foil so that the weight of the active material after drying was 0.05 g / cm ² , vacuum-dried at 120 ° C., and punched out into a 1 cmφ disk shape to obtain a positive electrode. Lithium metal was used as the negative electrode, and an equivalent mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) using 1M LiClO ₄ as a supporting salt was used as the electrolyte. A separator made of polyethylene was impregnated with an electrolytic solution, and a 2032 type coin battery was produced in a glove box in an Ar atmosphere in which the dew point was controlled at −80 ° C.
FIG. 1 shows a schematic structure of a 2032 type coin battery. Here, the coin battery is composed of a positive electrode (evaluation electrode) 3 in a positive electrode can 6, a lithium metal negative electrode 1 in a negative electrode can 5, an electrolyte-impregnated separator 2, a gasket 4, and a current collector 7.
The manufactured battery was allowed to stand for about 24 hours and after the OCV was stabilized, the current density was 0.5 mA / cm ² and a charge / discharge test was performed at a cut-off voltage 4.3-3.0 V to measure the initial discharge capacity. . Further, the discharge capacity after 25 cycles of the charge / discharge test was measured and evaluated as a relative ratio to the initial discharge capacity.

(5) Evaluation of safety (thermal stability) during charging: Disassembling a coin battery in a state where the charge cut voltage in the first cycle is set to 4.3 V, taking out the positive electrode mixture, and measuring by DSC The calorific value was determined and its thermal stability was evaluated. In addition, the calorific value of Example 1 was set to 100, and the relative ratio was shown.

Example 1
(1) Manufacture of plate-like nickel hydroxide powder As a raw material, it consists of a composition of Ni _0.82 Co _0.15 Al _0.03 (OH) ₂ manufactured by a normal crystallization method, and is granular water having a particle size of 5 μm. Using nickel oxide powder, 1 mol of this nickel hydroxide powder was suspended in 200 mL of an aqueous sodium hydroxide solution (content 2.5 mol) in a reaction vessel and sufficiently stirred. Thereafter, the reaction vessel was heated to 140 ° C. and held for 5 hours with stirring. After holding, it was washed with water and dried to obtain plate-like nickel hydroxide.
The obtained plate-like nickel hydroxide powder had a planar particle size of 10.6 μm and a specific surface area of 105 m ² / g, and the composition was the same as that of the raw material nickel hydroxide.

(2) Production of plate-like lithium nickel composite oxide Using a Spartan Luther, lithium hydroxide monohydrate was added to the plate-like nickel hydroxide powder in a molar ratio of Li / (Ni + Co + Al) = 1.02. The resulting mixture was calcined in an oxygen atmosphere at a temperature of 680 ° C. for 24 hours. The obtained fired product was crushed, classified with an ultrasonic sieve having a mesh of 50 μm, and then vacuum dried to obtain a plate-like lithium nickel composite oxide.
The obtained plate-like lithium nickel composite oxide was evaluated for particle size in the planar direction, composition, battery capacity after 25 cycles, and thermal stability. The results are shown in Table 1. Moreover, the SEM photograph of the external appearance of the obtained plate-like lithium nickel composite oxide is shown in FIG. 2, and the SEM photograph of the cross section is shown in FIG.

(Example 2)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that the firing temperature was 800 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 3)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 2 except that lithium oxide was used instead of lithium hydroxide monohydrate. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

Example 4
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 2 except that lithium chloride was used instead of lithium hydroxide monohydrate. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 5)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 2 except that lithium carbonate was used instead of lithium hydroxide monohydrate. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 6)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 2 except that lithium nitrate was used instead of lithium hydroxide monohydrate. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 7)
The plate-like nickel hydroxide obtained in Example 1 was roasted at 400 ° C. for 5 hours in the air atmosphere to produce plate-like nickel oxide. In the production of the plate-like lithium nickel composite oxide, plate-like hydroxide was produced. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 2 except that nickel was used instead of nickel. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 8)
When producing the plate-like nickel oxide, a plate-like lithium-nickel composite oxide was obtained in the same manner as in Example 7 except that the roasting temperature was 900 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

Example 9
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 2.5 mol, sodium chloride: 0.01 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that it was used. The plate-like nickel hydroxide obtained as an intermediate had a planar particle size of 9.8 μm, a thickness of 1.5 μm, and a specific surface area of 98 m ² / g, and its composition was the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1. Moreover, the specific surface area of the obtained plate-like lithium nickel composite oxide was 1.01 m ² / g.

(Example 10)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 2.5 mol, sodium chloride: 0.1 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that it was used. The plate-like nickel hydroxide obtained as an intermediate has a planar particle size of 10.1 μm, a thickness of 4.0 μm, and a specific surface area of 55 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 11)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 2.5 mol, sodium chloride: 0.2 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that it was used. The plate-like nickel hydroxide obtained as an intermediate has a planar particle size of 9.8 μm, a thickness of 7.6 μm, and a specific surface area of 51 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1. Moreover, the specific surface area of the obtained plate-like lithium nickel composite oxide was 0.43 m ² / g.

Example 12
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and calcium chloride (sodium hydroxide: 2.5 mol, calcium chloride: 0.1 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that it was used. The plate-like nickel hydroxide obtained as an intermediate had a planar particle size of 9.9 μm, a thickness of 3.9 μm, and a specific surface area of 64 m ² / g, and its composition was the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 13)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and nickel chloride (sodium hydroxide: 2.5 mol, nickel chloride: 0.1 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 1 except that it was used. The plate-like nickel hydroxide obtained as an intermediate has a planar particle size of 10.1 μm, a thickness of 4.0 μm, and a specific surface area of 68 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 14)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 10 except that the firing temperature was 800 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1. Moreover, the specific surface area of the obtained plate-like lithium nickel composite oxide was 0.71 m ² / g.

(Example 15)
The plate-like nickel hydroxide obtained in Example 10 was roasted at 400 ° C. for 5 hours in the air atmosphere to produce plate-like nickel oxide. In the production of the plate-like lithium nickel composite oxide, plate-like hydroxide was produced. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 14 except that this was used instead of nickel. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 16)
When producing plate-like nickel oxide, a plate-like lithium-nickel composite oxide was obtained in the same manner as in Example 15 except that the roasting temperature was 900 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 17)
In the manufacture of the plate-like nickel hydroxide powder, the composition of the nickel hydroxide used as a raw material _Ni 0.845 _Co 0.155 _(OH) Similarly tabular lithium nickel complex except which was a ₂ and Example 14 An oxide was obtained. The plate-like nickel hydroxide obtained as an intermediate has a planar particle size of 10.1 μm, a thickness of 4.6 μm, and a specific surface area of 74 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 18)
The plate-like nickel hydroxide obtained as the intermediate was roasted at 900 ° C. for 5 hours in the air atmosphere to produce plate-like nickel oxide. In the production of the plate-like lithium nickel composite oxide, A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 17 except that this was used instead of nickel. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

Example 19
In the production of the plate-like lithium nickel composite oxide, a molar ratio of Ni: Co: Al = 0.82: 0 was obtained in a slurry in which the plate-like nickel hydroxide was suspended in pure water to a concentration of 300 g / L. .15: Example except that sodium aluminate was dissolved to a composition of 0.03, neutralized by adding sulfuric acid, and the surface of the plate-like nickel hydroxide particles was coated with aluminum hydroxide. In the same manner as in Example 17, a plate-like lithium nickel composite oxide was obtained. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 20)
In the production of the plate-like lithium nickel composite oxide, aluminum oxide was added to the plate-like nickel hydroxide so that the molar ratio of Ni: Co: Al = 0.82: 0.15: 0.03. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 17 except that the surface of the plate-like nickel hydroxide particles was coated with aluminum oxide by mechanofusion. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 21)
The plate-like nickel hydroxide is roasted at 900 ° C. in an air atmosphere for 5 hours to produce plate-like nickel oxide. Instead of the plate-like nickel hydroxide, a slurry in which this is suspended is used to produce a plate-like nickel hydroxide. Example 19 except that the surface of the nickel oxide particles was coated with aluminum hydroxide and that the plate-like lithium nickel composite oxide was used in place of the plate-like nickel hydroxide. Thus, a plate-like lithium nickel composite oxide was obtained. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 22)
In the production of the plate-like lithium nickel composite oxide, the plate-like nickel hydroxide is submicron (in a molar ratio of Ni: Co: Al = 0.82: 0.15: 0.03). A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 17 except that aluminum hydroxide finely pulverized to 0.1 μm) was added and mixed using a V blender. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 23)
The plate-like nickel hydroxide was roasted at 900 ° C. in an air atmosphere for 5 hours to produce plate-like nickel oxide, and the aluminum hydroxide was added and mixed in place of the plate-like nickel hydroxide. Except this, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 22. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 24)
A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 23 except that aluminum oxide finely pulverized to submicron (0.1 μm) was used instead of the aluminum hydroxide. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 25)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 0.5 mol, sodium chloride: 0.1 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 14 except that it was used and the holding temperature was 100 ° C. The plate-like nickel hydroxide obtained as an intermediate had a planar particle size of 3.5 μm, a thickness of 2.8 μm, and a specific surface area of 104 m ² / g, and its composition was the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Example 26)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 5 mol, sodium chloride: 0.1 mol) was used as an aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 14 except that the holding temperature was 180 ° C. The plate-like nickel hydroxide obtained as an intermediate has a grain size in the plane direction of 18.5 μm, a thickness of 4.9 μm, and a specific surface area of 68 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Comparative Example 1)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 10 except that the firing temperature was 600 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Comparative Example 2)
In the production of the plate-like lithium nickel composite oxide, a plate-like lithium nickel composite oxide was obtained in the same manner as in Example 10 except that the firing temperature was 900 ° C. The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. In addition, precipitation of heterogeneous phase was observed. The results are shown in Table 1.

(Comparative Example 3)
In the production of the plate-like nickel hydroxide powder, a mixed aqueous solution of sodium hydroxide and sodium chloride (sodium hydroxide: 0.3 mol, sodium chloride: 0.1 mol) is used as the aqueous solution to be suspended instead of the aqueous sodium hydroxide solution. A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 14 except that it was used and the holding temperature was 100 ° C. The plate-like nickel hydroxide obtained as an intermediate has a plane direction particle size of 1.3 μm, a thickness of 2.2 μm, and a specific surface area of 155 m ² / g, and its composition is the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Comparative Example 4)
A plate-like lithium nickel composite oxide was obtained in the same manner as in Example 26 except that the holding temperature was 220 ° C. The plate-like nickel hydroxide obtained as an intermediate had a planar particle size of 24.5 μm, a thickness of 5.6 μm, and a specific surface area of 28 m ² / g, and its composition was the raw material nickel hydroxide It was the same.
The plate-like lithium nickel composite oxide obtained was evaluated for the particle size in the planar direction, the composition, the battery capacity after 25 cycles, and the thermal stability. The results are shown in Table 1.

(Comparative Example 5)
First, while maintaining the reaction temperature at 50 ° C. by a crystallization method in which an aqueous solution in which nickel sulfate and cobalt sulfate are mixed, an aqueous solution of sodium aluminate, ammonia water for forming an ammine complex salt, and caustic soda for pH adjustment are dropped into the reaction vessel. In this way, spherical nickel hydroxide having a composition of Ni _0.82 Co _0.15 Al _0.03 (OH) was obtained by maintaining the pH at 11 and controlling the residence time to be 8 hours.
Next, lithium hydroxide monohydrate was added to the obtained spherical nickel hydroxide using a Spartan Reuser so that the Li / (Ni + Co + Al) molar ratio = 1.02. The obtained mixture was baked for 24 hours at 800 ° C. in an oxygen atmosphere. The obtained fired product was crushed, classified with an ultrasonic sieve having a mesh size of 50 μm, and then vacuum dried to obtain a spherical lithium nickel composite oxide.
The average secondary particle diameter, composition, battery capacity after 25 cycles, and thermal stability of the obtained spherical lithium nickel composite oxide were evaluated. The average secondary particle size was measured by SEM observation as in Example 1. The results are shown in Table 1.

From Table 1, in Examples 1-26, plate-like nickel hydroxide having a planar particle size of 3-20 μm and a specific surface area of 50-150 m ² / g is used. A lithium compound is mixed with plate-like nickel oxide obtained by baking at a temperature of 400 ° C. to 900 ° C., and the resulting mixture is fired at a temperature of 680 to 800 ° C. Since it was performed according to the method, when used as a positive electrode active material for a lithium ion secondary battery, a secondary battery with high thermal stability and excellent cycle characteristics can be obtained, and a special porous material with large primary particles and excellent crystallinity It can be seen that a plate-like lithium nickel composite oxide having a porous structure is obtained.
On the other hand, in Comparative Examples 1 to 5, the firing temperature at the time of producing the lithium nickel composite oxide, the planar particle size of the plate-like nickel hydroxide used as the raw material, or the spherical nickel hydroxide meets these conditions. Therefore, it can be seen that satisfactory results are not obtained in any of the size, battery capacity or thermal stability of the lithium nickel composite oxide.

  2 and 3 show the porous structure of the plate-like lithium nickel composite oxide of the present invention. 2 and 3, the plate-like lithium nickel composite oxide of the present invention leaves a plate-like nickel hydroxide plate-like shape (for example, hexagonal plate-like) as a raw material. The structure is such that primary particles with a maximum diameter of 0.2 to 2 μm are intertwined to form secondary particles, and there are many voids continuously connected to the outside of the secondary particles between the primary particles. It can be seen that the structure has a porous structure.

As is clear from the above, the plate-like lithium nickel composite oxide of the present invention is suitable as a positive electrode active material for a lithium ion secondary battery, and by using this lithium ion having high safety and good cycle characteristics. Since a secondary battery is obtained, it is particularly suitable for a chargeable / dischargeable secondary battery used in the field of small electronic devices.
In addition, in the power source for electric vehicles, it is indispensable to ensure safety by increasing the size of the battery and an expensive protection circuit for ensuring higher safety. The secondary battery using nickel composite oxide has excellent safety, so that not only is it easy to ensure safety, but also an expensive protection circuit can be simplified and the cost can be reduced. In this case, it is also suitable as a power source for electric vehicles. In addition, it can be used not only as a power source for an electric vehicle driven purely by electric energy but also as a power source for a so-called hybrid vehicle used in combination with a combustion engine such as a gasoline engine or a diesel engine.

It is the perspective view and sectional drawing showing the coin battery used for battery capacity evaluation after 25 cycles of lithium nickel complex oxide. It is an external appearance SEM photograph of the plate-like lithium nickel complex oxide obtained in Example 1 of the present invention. It is a cross-sectional SEM photograph of the plate-like lithium nickel composite oxide obtained in Example 1 of the present invention.

Explanation of symbols

1 Lithium metal negative electrode 2 Separator (electrolyte impregnation)
3 Positive electrode (Evaluation electrode)
4 Gasket 5 Negative electrode can 6 Positive electrode can 7 Current collector

Claims (16)

A method for producing a plate-like lithium nickel composite oxide having a composition represented by the following formula (1):
Equation _{(1): Li y Ni 1} -x M x O 2
(In the formula, M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si, and x is 0 ≦ x ≦ 0.3. And y is 0.95 ≦ y ≦ 1.1.)
A method for producing a plate-like lithium nickel composite oxide comprising the following steps (1) to (3):
(1) A plate-like nickel hydroxide having a planar particle size of 3 to 20 μm and a specific surface area of 50 to 150 m ² / g is prepared.
(2) A lithium compound is added to the plate-like nickel hydroxide and mixed.
(3) The obtained mixture is fired at a temperature of 650 to 850 ° C.   Furthermore, the thickness of the said plate-shaped nickel hydroxide is 1-8 micrometers, The manufacturing method of the plate-shaped lithium nickel complex oxide of Claim 1 characterized by the above-mentioned. 3. The method for producing a plate-like lithium nickel composite oxide according to claim 1, wherein the composition of the plate-like nickel hydroxide is represented by the following formula (2).
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)   The plate-like nickel hydroxide is obtained by suspending nickel hydroxide in an aqueous solution containing an alkali metal hydroxide at a molar ratio of 0.5 times or more with respect to nickel hydroxide, and the temperature of the aqueous solution. The method for producing a plate-like lithium nickel composite oxide according to any one of claims 1 to 3, which is produced by stirring while maintaining at 90 to 190 ° C.   The said alkali metal hydroxide is at least 1 sort (s) chosen from sodium hydroxide, potassium hydroxide, or lithium hydroxide, The manufacturing method of the plate-shaped lithium nickel complex oxide of Claim 4 characterized by the above-mentioned.   Further, the aqueous solution contains an inorganic chloride such that the amount of chlorine contained in the inorganic chloride is 0.01 to 0.20 times the molar ratio with respect to nickel hydroxide. The method for producing a plate-like lithium nickel composite oxide according to claim 4 or 5.   The method for producing a plate-like lithium nickel composite oxide according to claim 6, wherein the inorganic chloride is at least one selected from alkali metal chloride, alkaline earth metal chloride, or nickel chloride. . The composition of the nickel hydroxide is represented by the following formula (2), and the inorganic chloride is at least one chloride of transition metal used as M in the following formula (2). The method for producing a plate-like lithium nickel composite oxide according to claim 6.
Formula (2): Ni _1-x M _x (OH) ₂
(However, x is 0 <x ≦ 0.3, and M is at least one element selected from transition metals other than Ni, alkaline earth metal elements, Al, Ti, Ga, In, or Si. is there.)   In the step (2), aluminum hydroxide or aluminum oxide is further added to the plate-like nickel hydroxide so that x in the formula (1) is 0 <x ≦ 0.3. The method for producing a plate-like lithium nickel composite oxide according to any one of claims 1 to 8.   The said aluminum hydroxide or aluminum oxide coat | covers the particle | grain surface of plate-like nickel hydroxide, The manufacturing method of the plate-like lithium nickel complex oxide of Claim 9 characterized by the above-mentioned. The plate-like lithium nickel composite oxide according to any one of claims 1 to 10, comprising the following steps (2-1) and (2-2) instead of the step (2): Manufacturing method.
(2-1) The plate-like nickel hydroxide is roasted at a temperature of 400 ° C. to 900 ° C. to obtain plate-like nickel oxide.
(2-2) A lithium compound is added to the plate-like nickel oxide and mixed.   In the step (2-2), aluminum hydroxide or aluminum oxide is added to the plate-like nickel oxide so that x described in the formula (1) is 0 <x ≦ 0.3. The method for producing a plate-like lithium nickel composite oxide according to claim 11.   The said aluminum hydroxide or aluminum oxide coat | covers the particle | grain surface of plate-like nickel oxide, The manufacturing method of the plate-like lithium nickel complex oxide of Claim 12 characterized by the above-mentioned.   The plate-like lithium nickel according to any one of claims 1 to 13, wherein the lithium compound is at least one selected from a hydroxide, oxide, chloride, carbonate, or nitrate of lithium. A method for producing a composite oxide. A plate-like lithium nickel composite oxide obtained by the method for producing a plate-like lithium nickel composite oxide according to any one of claims 1 to 14,
A plate-like lithium nickel composite oxide having a planar particle size of 3 to 20 μm and a porous structure.   The plate-like lithium nickel composite oxide according to claim 15, further having a thickness of 1 to 8 μm.

Images