JP2016155696A - Nickel hydroxide particle powder and manufacturing method therefor, cathode active material particle powder and manufacturing method therefor and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel hydroxide particle powder with high filling property and a manufacturing method therefor, a cathode active material particle powder of lithium nickel oxide with high filling property and a manufacturing method therefor and a nonaqueous electrolyte secondary battery having high energy density and excellent heat stability.SOLUTION: There are provided a nickel hydroxide particle powder having crystallite size in a vertical direction to a (00I) face with BET specific surface area of 0.5 to 8.0 m/g of 20 to 100 nm and crystallite size in a parallel direction to the (00I) face of 40 to 300 nm and a cathode active material particle powder of lithium nickel oxide having primary particle diameter of 2 to 15 μm, the amount of Niion to the total nickel amount of 10 mol% or less and BET specific surface area of 0.05 to 0.35 m/g.SELECTED DRAWING: None

Description

  The present invention provides a highly crystalline nickel hydroxide particle powder having a small specific surface area and a method for producing the same. The present invention also provides a lithium nickel oxide positive electrode active material particle powder having a large primary particle size, few structural defects, and a small specific surface area, and a method for producing the same. Furthermore, the present invention provides a nonaqueous electrolyte secondary battery that uses this and has excellent thermal stability and high energy density.

  In recent years, electronic devices such as mobile phones and personal computers have been spurred to be smaller and lighter, and the demand for secondary batteries having high energy density as power sources for driving these devices has increased. Under such circumstances, a battery having a large charge / discharge capacity per unit volume and volume and high safety is drawing attention.

Conventionally, lithium nickel oxide LiNiO ₂ having a layered (rock salt type) structure is known as one of positive electrode active material particle powders useful for a high energy type lithium ion secondary battery having a voltage of 4V class. Since the active material is cheaper and has excellent rate characteristics as compared with a typical positive electrode active material lithium cobalt oxide LiCoO ₂ , the active material is mainly used for a power tool main power source. In recent years, taking advantage of its characteristics, it is also being used as a drive power source for electric vehicles. However, there is a problem in thermal stability in a de-Li state containing Ni ⁴⁺ ions during charging, and further improvement in characteristics is required from the viewpoint of increasing energy density.

As is well known, the Li-free state of the positive electrode active material particle powder of lithium nickel oxide is a thermodynamically metastable phase. When heated to about 200 ° C., a phase transition from a layered structure to a rock salt structure or a spinel structure occurs, and oxygen release occurs from the oxide crystal as the valence from Ni ⁴⁺ decreases. Since the released oxygen reacts with the electrolyte and generates heat, it has a strong influence on the thermal stability of the battery. To suppress the oxygen release amount or to move the release start temperature to a higher temperature side is to improve the thermal stability of the battery, and as one method for improvement, substitution of different elements such as Co and Al has been proposed. (Patent Document 1).

  On the other hand, as a method for improving the filling property of the positive electrode active material particle powder of lithium nickel oxide, increasing the primary particles can be mentioned. As one of the methods, a method of increasing the primary particle diameter of the raw material nickel hydroxide particle powder has been proposed (Patent Document 2). Moreover, since it is almost synonymous with increasing the primary particle diameter of the lithium nickel oxide particle powder and increasing the crystallinity of the particle powder, the lithium nickel oxide having a large primary particle diameter is in the Li-free state. Improvement in thermal stability is expected.

  By the way, the manufacturing method of nickel hydroxide which controls the aggregated particle diameter by the crystallization method of liquid phase reaction has been known for a long time. As a known fact of increasing the aggregated particle diameter, a method of forming a nickel complex with a complexing agent is known in order to increase the solubility of nickel on the alkali side. This method is a crystallization method in which the complex is gradually decomposed with an alkaline solution and precipitated as nickel hydroxide having low solubility without generating new independent crystal nuclei (Patent Document 3).

  As a recent crystallization technique, a nickel raw material, a complexing agent, and a neutralizing agent are dropped in a multistage manner, and a method of synthesizing a high-density nickel hydroxide by controlling the aggregate particle size distribution is disclosed ( Patent Document 4).

JP-A-10-27611 Japanese Patent Laid-Open No. 11-60246 JP-A-7-206438 International Publication No. 2013/125703

  Highly chargeable nickel hydroxide particle powder and lithium nickel oxide positive electrode active material particle powder for secondary battery with high energy density and excellent thermal stability are currently the most demanded, but still sufficient Nothing has been obtained.

  That is, in the technique described in Patent Document 2, the primary particle diameter of nickel hydroxide is as large as 1 to 10 μm, and the crystallinity is considered high. However, the tap density of the particle powders of the examples is 2 g / cc or less, and it is difficult to say that the high filling property. Moreover, the primary particle diameter of the lithium nickel oxide particle powder obtained by mixing and firing the nickel hydroxide with the Li raw material is less than 2 μm as judged from the photograph, and is excellent in thermal stability in the delithiated state. It ’s hard to say.

The technique described in Patent Document 3 is to increase the median diameter of the aggregated nickel hydroxide particle powder to 10 to 20 μm. The particle powder disclosed therein has a high tap density of more than 2 g / cc and a high filling property, but the primary particle size is not specified. By analogy with the obtained BET specific surface area of 10 to 20 m ² / g, it is difficult to say that the primary particles are large and the crystallinity is high. At the same time, it is difficult to say that the positive electrode active material particle powder obtained by lithiating the nickel hydroxide is highly packable and excellent in thermal stability.

  The technique described in Patent Document 4 is to increase the median diameter of secondary particles in which nickel hydroxide is aggregated to 8 to 50 μm. The particle size distribution of the agglomerated particle diameter of the particle powder disclosed therein is also narrow, the tap density is as high as 1.9 g / cc or more, and it is highly packed, but the primary particle diameter is not specified and the crystallinity is high. It's hard to say. In addition, it is difficult to say that the positive electrode active material particle powder obtained by lithiating the nickel hydroxide has high filling property and excellent thermal stability.

  Then, this invention makes it a technical subject to provide the nickel hydroxide particle powder excellent in the filling property. In addition, a technical problem is to provide a positive electrode active material particle powder of lithium nickel oxide having excellent filling properties. Furthermore, it is a technical subject to provide a non-aqueous electrolyte secondary battery having a high energy density and excellent thermal stability.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention has a BET specific surface area of 0.5 to 8.0 m ² / g, a crystallite size perpendicular to the (00l) plane of 20 to 100 nm, and a crystallite size parallel to the (00l) plane of 40. Nickel hydroxide particle powder characterized by being -300 nm (Invention 1).

Further, in the present invention, the median diameter (D ₅₀ ) of the volume-based aggregated particles is 5 to 30 μm, and the ratio between the median diameter D ₅₀ and the peak width (D ₈₄ -D ₁₆ ) in the particle diameter frequency distribution. _{(D 84 -D 16) / D} 50 is nickel hydroxide particles according to the present invention 1 is 0.4 or less (present invention 2).

  Moreover, this invention is the nickel hydroxide particle powder of this invention 1 or 2 whose content of impurity sulfur S is 0.15 weight% or less (this invention 3).

  Further, the present invention is the nickel hydroxide particle powder according to any one of the present inventions 1 to 3, wherein at least one of Mg, Co, and Al is substituted with a part of Ni (the present invention). 4).

  In addition, the present invention continuously drops a nickel raw material, a complexing agent, and a neutralizing agent into a reactor equipped with a draft tube and a stirrer, and solid-liquid separates with a concentrator, so that the mother liquor in the reactor The volume was kept constant, the nickel raw material dropping rate into the reaction mother liquor was 0.02 to 0.25 [mol / (L · hr)], the complexing agent concentration was 0.3 to 1.5 mol / L, and neutralization The concentration of the surplus of the agent is 0.02 to 0.5 mol / L, the reaction temperature is 45 to 80 ° C., and the reaction time is 40 to 300 hours. This is a method for producing nickel hydroxide particle powder (Invention 5).

  Further, the present invention provides the method for producing particle powder according to the present invention 5, wherein the nickel raw material is at least one of nickel sulfate and nickel chloride, and the complexing agent is ammonia water, ammonium sulfate, or ammonium chloride. It is at least one kind, and the neutralizing agent is at least one kind selected from sodium hydroxide, sodium carbonate, and potassium hydroxide (Invention 6).

  Moreover, this invention uses the nickel hydroxide particle powder in any one of this invention 1-4, it mixes with a lithium raw material, and is baked at the temperature of 600-930 degreeC, The lithium nickel oxide characterized by the above-mentioned. It is a manufacturing method of positive electrode active material particle powder (this invention 7).

Further, the present invention is characterized in that the primary particle diameter is 2 to 15 μm, the amount of Ni ²⁺ ions with respect to the total nickel amount is 10 mol% or less, and the BET specific surface area is 0.05 to 0.35 m ² / g. It is a positive electrode active material particle powder of nickel oxide (Invention 8).

Further, in the present invention, the median diameter D ₅₀ of the aggregated particles is 5 to 30 μm, and the ratio (D ₈₄ -D ₁₆ ) between the median diameter D ₅₀ and the peak width (D ₈₄ -D ₁₆ ) in the particle size frequency distribution. _{16) / D 50} is the positive electrode active material particles of the lithium nickel oxide according to the present invention 8 is 0.6 or less (invention 9).

  Further, the present invention is a nonaqueous electrolyte secondary battery using the positive electrode active material particle powder of lithium nickel oxide according to the present invention 8 or 9 as at least a part of the positive electrode active material (Invention 10). .

  Since the nickel hydroxide particle powder according to the present invention has a low specific surface area and a large crystallite size, it exhibits a high filling property and is suitable as a precursor of a non-aqueous electrolyte secondary battery positive electrode active material. In addition, the positive electrode active material particle powder of lithium nickel oxide according to the present invention has a large primary particle size, few structural defects, and a low specific surface area. Suitable as particle powder. Furthermore, since the non-aqueous electrolyte secondary battery according to the present invention uses the positive electrode active material particle powder of lithium nickel oxide, it has a high capacity and starts to generate heat at a higher temperature in the de-Li state. Therefore, it is suitable as a nonaqueous electrolyte secondary battery having high energy density and excellent thermal stability.

It is a SEM photograph of the nickel hydroxide particle powder obtained in Example 1-1 of the present invention. It is a SEM photograph for (1) particle powder observation (low magnification), (2) for primary particle observation (medium magnification), and (3) for crystallite size observation (high magnification). (4) is an SEM photograph observed by solidifying nickel hydroxide particle powder with resin and cutting it with a cross section polisher (CP). It is a particle size distribution of the nickel hydroxide particle powder obtained in Example 1-1. It is the result of Rietveld analysis of the X-ray-diffraction pattern of the nickel hydroxide particle powder obtained in Example 1-1. The actual measurement values are shown in all diffraction angle ranges. It is a SEM photograph of the positive electrode active material particle powder of the lithium nickel oxide produced as Example 1-2 using the nickel hydroxide particle powder obtained in Example 1-1 as a raw material. (1) For particle powder observation (low magnification), (2) For primary particle observation (medium magnification), (3) For primary particle observation (high magnification), and (4) SEM photograph of particle cross section by CP. It is a SEM photograph of the nickel hydroxide particle powder obtained in Example 2-1. (1) is an SEM photograph of the nickel hydroxide particle powder obtained in Comparative Example 1-1 and (2) in Comparative Example 2-1. It is a cross-sectional SEM photograph of the nickel hydroxide particle powder obtained in Comparative Example 1-1. Li _1-a NiO ₂ (1-a≈0.2) obtained by performing Li removal treatment on the positive electrode active material particles of lithium nickel oxide obtained in Example 1-2 and Comparative Example 2-2 It is a differential scanning calorimetry result of positive electrode active material particle powder.

  The configuration of the present invention will be described in more detail as follows.

  First, the nickel hydroxide particle powder according to the present invention will be described.

  The nickel hydroxide particle powder according to the present invention is a particle powder characterized by having a small specific surface area, a large crystallite size, a relatively large aggregate particle diameter, but a uniform particle size. In addition, the inside of the aggregated particles is dense and is characterized by excellent filling properties.

The specific surface area of the nickel hydroxide particle powder according to the present invention is 0.5 to 8.0 m ² / g. It is industrially difficult to produce the particle powder having a particle size of less than 0.5 m ² / g, and the particle powder having a particle size exceeding 8.0 m ² / g tends to have a low density inside the particle. Is not preferable. Preferably, the specific surface area is 0.8 to 6.0 m ² / g.

  The crystallite size in the direction perpendicular to the (00l) plane of the nickel hydroxide particle powder according to the present invention is 20 to 100 nm. When it is less than 20 nm, the particle powder is difficult to be dense, which is not preferable from the viewpoint of high filling properties. In addition, since the particle powder has a layered structure that grows along the (001) plane, it is difficult for crystals to grow in a direction perpendicular to the plane, and it is industrially difficult to produce a film with a thickness exceeding 100 nm. Preferably, the crystallite size is 22-80 nm.

  The crystallite size in the direction parallel to the (00l) plane of the nickel hydroxide particle powder according to the present invention is 40 to 300 nm. When it is less than 40 nm, the particle powder is difficult to be dense, which is not preferable from the viewpoint of high filling properties. Moreover, it is industrially difficult to manufacture beyond 300 nm. Preferably, the crystallite size is 50-200 nm.

  The ratio of the crystallite size in the direction parallel to the crystallite size in the direction perpendicular to the (00l) plane of the nickel hydroxide particle powder according to the present invention is 2 to 7. It is industrially difficult to produce nickel hydroxide particle powder having a ratio outside this range. Preferably, it is 2.5-6.

The chemical formula of the nickel hydroxide particle powder according to the present invention is β-Ni (OH) ₂ and has a trigonal layered structure of the space group P3-m1. Here, it is correct to describe − on 3 as a space group mark, but for convenience, it is 3−. The particle powder has a nickel valence of two. Further, it does not matter if the particle powder contains β-NiOOH or γ-NiOOH.

The nickel hydroxide particle powder according to the present invention is a structure in which primary particles are aggregated, and the median diameter (D ₅₀ ) of the volume-based aggregated particles is preferably 5 to 30 μm. If it is less than 5 μm, the tap density tends to be low, which is not preferable from the viewpoint of high filling properties. When exceeding 30 micrometers, it exists in the tendency which worsens the below-mentioned particle size distribution. More preferably, the median diameter (D ₅₀ ) is 7 to 28 μm.

In the volume-based aggregate particle size distribution of the nickel hydroxide particle powder according to the present invention, the ratio (D ₈₄ -D ₁₆ ) between the median diameter (D ₅₀ ) and the peak width (D ₈₄ -D ₁₆ ) of the frequency distribution. / the _{D 50} was a measure of the narrowness of the particle size distribution, it said value is preferably 0.4 or less. When it exceeds 0.4, it means that the peak of the frequency distribution is wide, and the distribution tends to occur in the particle size and crystallinity of LiNiO ₂ produced by mixing with Li source and firing. More preferably, the _{(D 84 -D 16) / D} 50 is 0.38 or less.

  The content of impurity sulfur S in the nickel hydroxide particle powder according to the present invention is preferably 0.15% by weight or less. If it exceeds 0.15% by weight, the capacity may be reduced or the charge / discharge cycle may be deteriorated due to side reactions.

In the nickel hydroxide particle powder according to the present invention, a part of Ni in the chemical formula β-Ni (OH) ₂ can be substituted with at least one of Mg, Co, and Al. The target particle powder can be produced by dropping predetermined amounts of Mg, Co and Al raw material solutions during the solution reaction. The positive electrode active material particle powder of lithium nickel oxide produced by mixing and firing the nickel hydroxide particle powder substituted with the element and the Li raw material can dissolve the element more uniformly.

  In the nickel hydroxide particle powder according to the present invention, the residual impurity element components such as Mg, Co, and Na excluding Al and sulfur S are preferably 1000 ppm or less. This is because if the value (1000 ppm) is exceeded, the battery characteristics may be adversely affected.

  In the nickel hydroxide particle powder according to the present invention, the tap density by tapping 500 times is preferably 2.15 to 3.00 g / cc. When it is less than 2.15 g / cc, it is difficult to say that the filling property is high. When it exceeds 3.00 g / cc, it is difficult to obtain a particle powder satisfying other characteristics.

  Next, a method for producing nickel hydroxide particle powder according to the present invention will be described.

  The nickel hydroxide particle powder production method according to the present invention employs a liquid phase method for producing the particle powder in a reaction mother liquor composed of an aqueous solvent, and in order to increase the aggregated particle diameter, A crystallization method via decomposition is used. A nickel raw material, a complexing agent, and a neutralizing agent and, if necessary, one or more selected from Mg, Co, and Al raw materials are appropriately added dropwise to the reactor. The nickel raw material is used as a main raw material for obtaining the target nickel hydroxide particle powder, and the Mg, Co, and Al raw materials added as necessary are used as additive raw materials for replacing Ni.

  In the method for producing nickel hydroxide particle powder according to the present invention, the nickel raw material may be at least one of nickel sulfate and nickel chloride. Mg, Co, and Al raw materials are magnesium sulfate heptahydrate, cobalt sulfate heptahydrate, and aluminum sulfate.

  In the method for producing nickel hydroxide particle powder according to the present invention, the complexing agent may be at least one of ammonium water, ammonium sulfate, or ammonium chloride, which is an ammonium ion supplier. As the neutralizing agent, at least one of sodium hydroxide, sodium carbonate, or potassium hydroxide can be used. Since these listed raw materials and drugs are relatively inexpensive and readily available, they can be used industrially.

  The manufacturing method of the nickel hydroxide particle powder according to the present invention follows a crystallization method, and in order to mix the raw material to be dropped, the complexing agent and the neutralizing agent uniformly and efficiently, a draft tube and a stirrer are used. Equipped with a reactor. By continuously dropping the raw material, the complexing agent and the neutralizing agent, the volume of the reaction mother liquor (aqueous solution), the concentration of the complexing agent in the reaction mother liquor, and the concentration of the neutralizing agent are not changed. Then, solid-liquid separation is performed with a concentrator. The influence of the dropping conditions on the properties of the nickel hydroxide particle powder produced is investigated, and the nickel hydroxide particles that are densely aggregated are grown as much as possible without generating new crystal nuclei outside the surface of the particles.

  In the method for producing nickel hydroxide particle powder according to the present invention, the dropping rate of the nickel raw material per volume of the reaction mother liquor in the crystallization method is 0.02 to 0.25 [mol / (L · hr)]. When it is less than 0.02 [mol / (L · hr)], the fineness of the particle powder and the narrowness of the particle size distribution are not improved, which is not efficient. Moreover, when exceeding 0.25 [mol / (L * hr)], many crystal nuclei produced | generated and the fine aggregated particle produced | generated. Moreover, if this dripping rate is this range, you may change dripping rate during reaction.

  In the method for producing nickel hydroxide particle powder according to the present invention, the complexing agent is used to form a highly soluble nickel complex. The concentration of the complexing agent in the reaction mother liquor is 0.3 to 1.5 mol / L. When it is less than 0.3 mol / L, it becomes difficult to form a nickel complex, and the produced nickel hydroxide aggregated particles do not grow greatly. When the concentration exceeds 1.5 mol / L, a highly soluble nickel complex is excessively generated and is discharged out of the liquid phase reaction system during solid-liquid separation by a concentrator, resulting in a decrease in the yield of the resulting nickel hydroxide particle powder. To do. Preferably it is 0.5-1.3 mol / L.

In the method for producing nickel hydroxide particle powder according to the present invention, the neutralizing agent is used for neutralizing the raw material or decomposing the nickel complex to grow primary particles and agglomerated particles largely. In order to precipitate the nickel hydroxide particle powder while keeping the reaction mother liquor alkaline, an alkaline neutralizing agent is excessively added to the NiSO ₄ raw material exhibiting acidity. Here, the surplus of the neutralizing agent means, for example, that the number of moles necessary for the neutralization of NiSO ₄ is more than the amount of NaOH added to control the reaction mother liquor to a high pH value. Let the amount of NaOH be the surplus.

  In the method for producing nickel hydroxide particle powder according to the present invention, the concentration of excess neutralizing agent in the reaction mother liquor is 0.02 to 0.5 mol / L. When the concentration is less than 0.02 mol / L, the neutralization of the raw material or the highly soluble nickel complex is not decomposed, and the solid-liquid separation by the concentrator is discharged out of the liquid phase reaction system to collect the nickel hydroxide particle powder. The rate drops. When it exceeds 0.5 mol / L, the production rate of nickel hydroxide is increased, and a large number of crystal nuclei are generated to form fine particles, so that a desired aggregate particle diameter cannot be obtained. Preferably it is 0.03-0.45 mol / L.

  In the method for producing nickel hydroxide particle powder according to the present invention, the temperature of the reaction mother liquor is in the range of 45 to 80 ° C. When the temperature is lower than 45 ° C., the crystallites of the particle powder do not grow and the specific surface area increases, and as a result, nickel hydroxide particle powder with low filling property is obtained. When it exceeds 80 ° C., the amount of evaporation of ammonia cannot be ignored, and the industrial load becomes high, preferably 50 to 75 ° C.

  The reaction time in the method for producing nickel hydroxide particle powder according to the present invention is in the range of 40 to 300 hours. When the time is less than 40 hours, neither the crystallites nor the aggregated particles of the particle powder grow sufficiently, the specific surface area increases, and as a result, nickel hydroxide particle powder with low filling property is obtained. If it exceeds 300 hours, the concentration of nickel hydroxide particles in the reaction mother liquor becomes too high, and uniform mixing becomes difficult. Preferably, it is 50 to 200 hours.

  The nickel hydroxide particle powder according to the present invention is used to remove a complexing agent that can be an impurity after the crystallization reaction in the liquid phase, an excess neutralizing agent, and sulfate and chloride generated by the neutralization reaction. It may be washed with water and dried.

  Next, the positive electrode active material particle powder of lithium nickel oxide according to the present invention and the production method thereof will be described.

The chemical formula of the positive electrode active material particle powder of lithium nickel oxide according to the present invention is LiNiO ₂ and takes a trigonal layered (rock salt) structure of space group R3-m having Ni ³⁺ ions. Here, in general,-in the space group is written on 3 but is described in this way for convenience. Moreover, it is possible to substitute at least one of Mg, Co, and Al for a part of Li and Ni in the particle powder.

  The method for producing positive electrode active material particle powder of lithium nickel oxide according to the present invention uses the nickel hydroxide particle powder obtained in the present invention as a precursor, mixes the precursor with a lithium raw material, and fires the obtained mixture To do. The lithium raw material is not particularly limited, but lithium carbonate, lithium hydroxide, and lithium hydroxide monohydrate are used.

  The positive electrode active material particle powder of lithium nickel oxide according to the present invention is prepared based on a solid phase reaction method by firing a mixture of the precursor and raw material obtained by the above operation. The solid phase reaction is a method of obtaining a target phase by mixing raw materials containing constituent elements and promoting a chemical reaction between solid raw materials by high-temperature heat treatment. In order to facilitate the diffusion of lithium during the solid phase reaction with the precursor, the lithium raw material preferably has a fine particle size. The precursor and the raw material are preferably mixed by a dry method without using a solvent. As a raw material powder mixing device, a raking machine, a ball mill, a Henschel mixer, a high speed mixer, or the like can be used.

As is well known, in lithium nickel oxide, a structural defect occurs in which a part of nickel becomes Ni ²⁺ ions and is replaced with Li ⁺ ions in the crystal during firing at a higher temperature, thereby impairing battery characteristics. Further, it is known that NiO is generated by firing at a higher temperature. (Non-Patent Document 1)

[Non-Patent Document 1] Arai, et al., “Characterization and cathode performance of Li _1-x Ni _{1 + x} O ₂ prepared with the exact lithium method”, Solid State Ionics, 1995, 1st volume, 1995, 1st volume. 261-269.

In the positive electrode active material particle powder of lithium nickel oxide according to the present invention, the amount of Ni ²⁺ ions with respect to the total nickel amount is 10 mol% or less, and there are very few structural defects. This is because the crystallite size of nickel hydroxide can be increased in the present invention, and even if it is fired at a low temperature using it as a precursor, a positive active material particle powder of lithium nickel oxide having a large primary particle size can be obtained. .

The method for producing a positive electrode active material particle powder of lithium nickel oxide according to the present invention is characterized in that the mixture is fired in a temperature range of 600 to 930 ° C. When the firing temperature is less than 600 ° C., the solid phase reaction does not proceed sufficiently, and the desired positive electrode active material particle powder of lithium nickel oxide cannot be obtained. When the temperature exceeds 930 ° C., the amount of Ni ²⁺ ions substituted for lithium sites as structural defects increases and grows as a NiO impurity phase. Preferably it is 700-900 degreeC.

  As a firing condition in the method for producing a positive electrode active material particle powder of lithium nickel oxide according to the present invention, firing in an atmosphere having a high oxygen concentration is desirable. The holding time of the calcination temperature is about 5 to 15 hours, and the temperature raising and lowering rate is about 50 to 200 ° C./hour. As the firing furnace, a gas flow box muffle furnace, a gas flow rotary furnace, a roller hearth kiln, or the like can be used.

  In the method for producing a positive electrode active material particle powder of lithium nickel oxide according to the present invention, the particle powder obtained by firing may be pulverized and classified. Examples of the pulverizer include a rough machine, an impact pulverizer, and a fluid pulverizer. By pulverizing and classifying, the particle size of the particle powder can be made more uniform.

The primary particle diameter of the positive electrode active material particle powder of lithium nickel oxide according to the present invention is 2 to 15 μm. If it is less than 2 μm, the thermal stability in the de-Li state is insufficient, and it is industrially difficult to reduce the structural defects of the crystal accompanied by the formation of Ni ²⁺ exceeding 15 μm. Preferably, it is 2.5-10 micrometers, More preferably, it is 3-8 micrometers.

The BET specific surface area of the positive electrode active material particle powder of lithium nickel oxide according to the present invention is 0.05 to 0.35 m ² / g. It is industrially difficult to reduce structural defects at less than 0.05 m ² / g. When the Li-free compound is produced at a rate exceeding 0.35 m ² / g, the thermal stability is insufficient. Preferably, it is 0.07-0.30 m < ² > / g.

The ratio of the positive electrode active material particle median diameter D ₅₀ of aggregated particles of the powder of the lithium nickel oxide according to the present invention is preferably from 5 to 30 [mu] m, the peak width in the frequency distribution of the aggregated particle diameter (D _{84 -D 16) (D 84 -D 16) / D} 50 is preferably 0.6 or less. In order to obtain a narrow particle size distribution, the particle powder is generated under conditions that reflect the particle size distribution of the nickel hydroxide used as the precursor. The positive electrode active material particle powder having a narrow particle size distribution has high dispersibility, and handling properties are improved.

  Next, a non-aqueous electrolyte secondary battery using the positive electrode active material particle powder of lithium nickel oxide according to the present invention will be described.

  When manufacturing a positive electrode sheet using the positive electrode active material particle powder according to the present invention, a conductive agent and a binder are added and mixed according to a conventional method. As the conductive agent, carbon black, graphite or the like is preferable. As the binder, polytetrafluoroethylene, polyvinylidene fluoride and the like are preferable. For example, N-methyl-pyrrolidone is preferably used as the solvent. The slurry containing the positive electrode active material particle powder, the conductive material and the binder is kneaded until it becomes honey. The obtained positive electrode mixture slurry is applied onto a current collector with a doctor blade having a groove of 25 μm to 500 μm at a coating speed of about 60 cm / sec, and dried at 80 to 180 ° C. to remove the solvent and soften the binder. An Al foil of about 20 μm is used for the current collector. The current collector coated with the positive electrode mixture is subjected to a calender roll treatment with a linear pressure of 0.1 to 3 t / cm to obtain a positive electrode sheet.

  Since the positive electrode active material particle powder according to the present invention has a high compression-molded body density and a low BET specific surface area, the amount of binder added to the positive electrode mixture slurry can be reduced, and as a result, a high-density positive electrode sheet is obtained. Moreover, a higher-density positive electrode sheet can be obtained by mixing a positive electrode active material having a small particle diameter with a median diameter of 1 to 7 μm.

  As the negative electrode active material, lithium metal, lithium / aluminum alloy, lithium / tin alloy, graphite or the like can be used, and the negative electrode sheet is produced by the same doctor blade method or metal rolling as the positive electrode.

  In addition to the combination of ethylene carbonate and diethyl carbonate, an organic solvent containing at least one of carbonates such as propylene carbonate and dimethyl carbonate and ethers such as dimethoxyethane can be used as the solvent for the electrolytic solution.

  Further, as the electrolyte, in addition to lithium hexafluorophosphate, at least one lithium salt such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in the above solvent and used.

  The secondary battery of the counter electrode Li manufactured using the positive electrode active material particle powder according to the present invention has an initial discharge capacity after charging of 4.3 V at 25 ° C. of 155 mAh / g or more, and a Coulomb efficiency of 70. % Or more.

The stability of the positive electrode active material particle powder in the de-Li state corresponding to the charged state using the positive electrode active material according to the present invention can be evaluated by the stability against thermal decomposition, and the de-Li state can be created chemically. The Li _1-a NiO ₂ (1-a≈0.2) obtained by removing Li from the positive electrode active material particle powder according to the present invention has an exothermic start temperature in the atmosphere of 205 ° C. or higher, and is excellent in thermal stability. .

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Since the nickel hydroxide particle powder according to the present invention has a small specific surface area and a large crystallite size, it has excellent filling properties. Therefore, the primary particle diameter of the positive electrode active material particle powder of lithium nickel oxide obtained by mixing it with a lithium raw material and calcining is large, and the filling property is high. The secondary battery using the particle powder has a high capacity and tends to be thermally decomposed at a higher temperature in the de-Li state, and is excellent in thermal stability.

  Specific examples of implementation of the present invention are shown below.

A predetermined amount of nickel sulfate hexahydrate NiSO ₄ .6H ₂ O was dissolved in pure water to obtain a nickel raw material solution. A concentration of ammonia water NH ₄ OH as a complexing agent and caustic soda NaOH as a neutralizing agent was diluted with pure water to adjust the concentration. Additive amounts of cobalt sulfate heptahydrate CoSO ₄ · 7H ₂ O, magnesium sulfate heptahydrate MgSO ₄ · 7H ₂ O, aluminum sulfate Al ₂ (SO ₄ ) ₃ · 16H ₂ O to pure water Dissolved.

As a lithium raw material, dry-pulverized lithium hydroxide / monohydrate LiOH / H ₂ O was used.

  The powder evaluation of the nickel hydroxide particle powder of the present invention was performed as follows.

  A field emission scanning electron microscope (FE-SEM) S-4300 [Hitachi High-Technologies Corporation] was used to observe the sample surface and shape. Further, in order to prepare a sample for observing a particle cross section, the particle powder was embedded in a resin and cut with a cross section polisher (CP) SM-09010 [JEOL Ltd.].

  The BET specific surface area of the sample was measured by drying and degassing the sample under nitrogen gas at 120 ° C. for 45 minutes and then using Macsorb [Mounttech Co., Ltd.].

In order to identify the crystal phase of the sample and calculate the crystal structure parameters, the measurement was performed using a powder X-ray diffractometer SmartLab [Rigaku Corporation]. The X-ray diffraction pattern was measured through a monochromator under the conditions of Cu-Kα, 45 kV, 200 mA, and the Step-Scan method was performed at a step of 0.02 ° so that the maximum peak intensity count number was 10,000 or more. Measured with ZnO of SRM674b the NIST (National Institute of Standards and Technology ), and LaB ₆ of SRM660b used as an external standard sample was used RIETAN2000 the Rietveld analysis program.

  In the X-ray diffraction pattern of nickel hydroxide particle powder, there is a report of Non-Patent Reference 2 that the diffraction peak broadens due to stacking faults on the (hOl) plane, and a diffraction angle of 35 to 42 ° including the peak derived from the crystal plane is reported. The range of 47-56.5 ° was not used for the analysis. In addition, the crystallite size was handled anisotropically with the (00l) plane as a plate-like crystallite plane.

[Non-Patent Document 2] N. Ramesh, two others, Acta Crystallogr. , “Classification of stacking faults and ther stepwise elinlination the therder → order transformation of nickel hydride, April 11, 2006, p. 530-536.

A laser diffraction / scattering particle size distribution meter [Seishin Enterprise Co., Ltd.] was used for measuring the volume-based aggregate particle size distribution of the sample. As the width of the peak of the frequency distribution _was used (D 84 _{-D 16).} Here, the n value of D _n means the particle diameter when n% in the cumulative distribution. _{That, D 84} and _{D 16} is a particle diameter when the 84% and 16% in the cumulative distribution of each.

  The amount of residual sulfur S in the sample was quantified by burning the sample in an oxygen stream in a combustion furnace using EMIA-820 [manufactured by Horiba Ltd.].

  The sample tap density was measured after filling 40 g of a sample into a 100 ml graduated cylinder and tapping 500 times using a tamp denser (KYT-3000, manufactured by Seishin Enterprise Co., Ltd.).

  The Ni content in the nickel hydroxide particle powder was quantified by chelate titration. After 2.5 g of nickel hydroxide particle powder was precisely weighed and dissolved in 25 ml of high-concentration hydrochloric acid, it was adjusted to 250 ml with 0.12N hydrochloric acid. To 25 ml of this solution, 10 ml of a 0.005 g / ml Cu · EDTA solution and 5 ml of a solution prepared by adjusting 10 g of ammonium chloride to 100 cc with pure water were added and adjusted to 100 ml to obtain a measurement solution. Using a potentiometric automatic titration apparatus [Metrohm Co., Ltd.], 0.1M 2Na · EDTA and ammonia were automatically titrated into the measurement solution, and the amount of Ni in the nickel hydroxide particle powder was determined.

  The powder evaluation of the positive electrode active material particle powder of the lithium nickel oxide of the present invention and the evaluation of the secondary battery using the same were performed as follows.

  The contents of lithium and nickel, which are main component elements of the positive electrode active material particle powder, and cobalt, magnesium and aluminum as accessory components are determined by completely dissolving the sample powder with 20% hydrochloric acid, and then an ICP emission spectroscopic analyzer (ICP -OES) Measured by a calibration curve method using Optima 8300 [Perkin Elmer Japan Co., Ltd.]. At the same time, the amount of impurities was quantified.

  The primary particle diameter of the positive electrode active material particle powder was the average of the primary particle diameters of about 25 particles measured from a photograph of medium magnification (x5000) of FE-SEM as shown in FIG. 4 (2).

The amount of Ni ²⁺ ions Ni ²⁺ / (Ni ²⁺ + Ni ³⁺ ) with respect to the total amount of nickel in the positive electrode active material particle powder used Rietveld analysis in an X-ray diffraction pattern. Here, the total nickel amount is composed of Ni ²⁺ ions and Ni ³⁺ ions forming each phase. In the crystalline phase of LiNiO ₂ of the particle powder, Ni existing at the lithium site was regarded as Ni ²⁺ ions, and Ni present at the nickel site was regarded as Ni ³⁺ ions. At the same time, Ni present in the impurity phase NiO was also regarded as Ni ²⁺ ions.

Positive electrode active material agglomerate BET specific surface area of the particles the particle median diameter D ₅₀ was measured in the same apparatus and nickel hydroxide. Using aggregate particle median diameter _{D 50} obtained represents the narrowness of the particle size distribution _{(D 84 -D 16) / D} 50 was calculated.

The density of the compression molded body of the positive electrode active material particle powder was calculated from the weight and volume of a molded body obtained by compacting a 5 g sample with a 10 mmφ jig at a pressure of 2.5 t / cm ² .

The primary particle diameter of the obtained positive electrode active material particle powder, the amount of Ni ²⁺ ions with respect to the total nickel amount Ni ²⁺ / (Ni ²⁺ + Ni ³⁺ ), the BET specific surface area, the agglomerated particle median diameter D ₅₀ , and the narrow particle size distribution of the agglomerated particles It is the measure _{(D 84 -D 16) / D} 50, compact density illustrated as powder characteristics in Table 2. At the same time, the firing temperature was noted.

  Using the obtained positive electrode active material particle powder, the secondary battery characteristics in a CR2032-type coin cell by the following production method were evaluated and are shown in Table 2.

  The positive electrode active material and the conductive agent acetylene black, graphite, and the binder polyvinylidene fluoride are precisely weighed so as to have a weight ratio of 90: 3: 3: 4, dispersed in N-methyl-2-pyrrolidone, and kneaded at high speed. The positive electrode mixture slurry was prepared by thoroughly mixing with an apparatus. Next, the mixture slurry was applied to an aluminum foil as a current collector with a doctor blade, dried at 120 ° C., and pressurized to 0.5 t / cm to produce a positive electrode sheet having a thickness of about 40 μm. A positive electrode sheet was punched to 16 mmφ to obtain a positive electrode.

  As the negative electrode, a metal lithium foil [Honjo Metal Co., Ltd.] punched to 16 mmφ was used.

As a separator, Celgard # 2400 [Celgard, LLC] 20 mmφ was used. EC and DMC (ethylene carbonate: dimethyl carbonate = 1: 2 volume ratio) mixed solvent in which 1 mol / l LiPF ₆ was dissolved was used as an electrolytic solution. These members were assembled to produce a CR2032-type coin cell [Hosen Co., Ltd.].

  The battery was assembled in a glove box in an argon atmosphere so that the electrolyte and metallic lithium were not decomposed by the air.

  The measurement of the initial discharge capacity at 25 ° C. was performed under the condition that the lower limit of the discharge voltage was 3.0 V and the upper limit of the charge voltage was 4.3 V under a constant current of 0.1 C.

In order to evaluate the thermal stability of the secondary battery, a positive electrode active material particle powder in a de-Li state corresponding to the charged state was chemically produced, and the calorific value at the time of temperature rise was measured. That is, the obtained lithium nickel oxide positive electrode active material particle powder was immersed in 6 M sulfuric acid at 7 ° C., stirred for 48 hours, washed with water, and dried to chemically remove Li. Here, using a disproportionation reaction of Ni ³⁺ → Ni ²⁺ + Ni ⁴⁺ , Li ⁺ ions, Ni ²⁺ ions, and excess (SO ₄ ) ²⁻ ions in the reaction solution are removed by water washing, and Li containing Ni ⁴⁺ is contained. _1-a NiO ₂ (1-a≈0.2) can be obtained. Differential scanning calorimetry (DSC) of the delithiated positive electrode active material particles was performed. The DSC curve was obtained by measuring with DSC-6200 [Seiko Instruments Inc.] at a heating rate of 10 ° C./min in an air atmosphere. As shown in FIG. 8, the heat generation start temperature was obtained from the intersection of the extrapolated DSC curve base line and the tangent at the inflection point on the low temperature side of the heat generation peak.

[Example 1-1]
(Preparation of nickel hydroxide particle powder)
In a reactor having an effective volume of 10 L equipped with a draft tube, a baffle and a blade-type stirrer, the reaction mother liquor volume is 8 L, the reaction temperature is 60 ° C., NH ₄ OH is 1.2 mol / l, and NaOH is 0.2 mol / l. Was adjusted with sufficient stirring. For raw material dropping, 1.55 mol / l NiSO ₄ aqueous solution, 5.41 mol / l NH ₄ OH aqueous solution, and 5.99 mol / l NaOH aqueous solution were prepared in individual containers, respectively. The NiSO ₄ aqueous solution was dropped into the reactor at a rate of 0.05 mol / hr per liter of the reaction mother liquor, and solid-liquid separation was performed with a concentrator so that the reaction mother liquor volume was constant. At the same time, the NH ₄ OH concentration in the reaction mother liquor was dropped to 1.2 mol / l, and the excess NaOH was added dropwise to 0.2 mol / l with respect to the neutralization of the NiSO ₄ aqueous solution.

  The reaction mother liquor during the solution reaction was withdrawn each time and washed with water, and the obtained particle powder was measured with a laser diffraction / scattering particle size distribution meter. 120 hours after the start of dropping, the starting of dropping of the aggregated particles was stopped, and the dropping of the raw material was stopped to complete the solution reaction. After washing with water and drying, nickel hydroxide particle powder was prepared.

The obtained nickel hydroxide particle powder had almost no fine powder and had a uniform particle size, as shown in FIG. 2, and as shown in Table 1, the median diameter _{D 50} of from volume-based particle size distribution is 6.9 [mu] m, the ratio of the width _(D 84 _{-D 16)} and _{D 50} of the particle size distribution of said volume standard ( D ₈₄ -D ₁₆ ) / D ₅₀ was as small as 0.31, and almost coincided with the particle size of the low-magnification SEM photograph. As shown in the SEM photograph of FIG. 1 (2), primary particles of about 0.7 μm aggregate to form aggregated particles of about 7 μm. As shown in the particle cross-sectional SEM photograph of FIG. It was a fine aggregated particle as a whole. As shown in the high-magnification SEM photograph of FIG. 1 (3), it was observed that crystallites with a thickness of several tens of nm overlapped to form primary particles.

As shown in the analysis result of the X-ray diffraction pattern in FIG. 3, since the reliability factor R _wp was as low as 14.2%, it was considered that analysis was possible in the space group P3-m1. The lattice constants as a hexagonal system, a = 3.129 Å and c = 4.637 Å were obtained, and it was found that β-Ni (OH) ₂ was obtained. The crystallite sizes in the direction perpendicular to and parallel to the (00l) plane were 32 nm and 123 nm, respectively, which were observed almost the same as the size of the plate-like particles in the SEM photograph of FIG. Therefore, it was considered that primary particles of about 0.7 μm were formed by overlapping plate-like crystallites of the size.

The BET specific surface area was 2.9 m ² / g, the tap density of 500 times was 2.25 g / cc, and it was found that the filling property was excellent. Further, the amount of residual sulfur S was as low as 0.06% by weight, and the purity was high.

Table 1 shows the powder characteristics and production conditions of the obtained nickel hydroxide particles. As the powder characteristics, the BET specific surface area, the crystallite size perpendicular (方向) and parallel (//) to the (00l) plane, the crystallite size perpendicular to the (00l) plane, The ratio of the crystallite size, the median diameter of aggregated particle D ₅₀ , the standard of narrowness of particle size distribution (D ₈₄ -D ₁₆ ) / D ₅₀ , the amount of residual sulfur S, and the tap density of 500 times. The production conditions are nickel raw material dropping rate, NH ₄ OH concentration, neutralized surplus NaOH concentration, reaction temperature, and reaction time.

[Example 1-2]
(Preparation of positive electrode active material particle powder of lithium nickel oxide)
The Ni content of the obtained nickel hydroxide particle powder was 10.7 mol / kg according to chelate titration. 150 g of the particle powder was weighed. As a lithium source, lithium hydroxide LiOH.H ₂ O was charged and weighed so that the ratio Li / Ni = 1.05 mol. Using a desktop mixer having stirring blades, after dry mixing, it was fired at 860 ° C. for 10 hours in an oxygen atmosphere. The obtained sample was classified using a sieve having an opening of 45 μm while being pulverized in a mortar.

  An SEM photograph of the obtained positive electrode active material particle powder of lithium nickel oxide is shown in FIG. Judging from FIG. 4 (1), the primary particle size showed a value close to the aggregated particle size. Judging from FIG. 4 (2), the primary particle size was about 4 μm. As shown in the SEM photograph of the cross section of the particle in FIG. 4 (4), it was found to be a dense structure.

Table 2 shows the powder characteristics of the obtained positive electrode active material particle powder of lithium nickel oxide. The amount of Ni ²⁺ ions Ni ²⁺ / (Ni ²⁺ + Ni ³⁺ ) relative to the total amount of nickel by analysis of the X-ray diffraction pattern was 6 mol%, and there were few structural defects in the crystals of the particle powder. Since the primary particle diameter of the particle powder was large, the BET specific surface area was as low as 0.22 m ² / g. The median diameter D ₅₀ of the agglomerated particles was 7.6 μm, and the standard (D ₈₄ -D ₁₆ ) / D ₅₀ of the narrow particle size distribution was as low as 0.49, and the particle sizes were uniform. Even when the low-magnification SEM photographs of FIG. 1 (1) and FIG. 4 (1) are compared, the aggregated particle diameter of the nickel hydroxide particle powder obtained in Example 1-1 and the positive electrode active material of the lithium nickel oxide The particle size of the particle powder is highly correlated, and it is expected that the lithium raw material is decomposed and diffused into the nickel particles. The density of the compression molded product was as high as 3.3 g / cc.

  The obtained positive electrode active material particle powder of lithium nickel oxide was converted into a positive electrode and evaluated in a coin cell. As shown in Table 2, the initial discharge capacity and initial coulomb efficiency were as high as 170 mAh / g, and the coulomb efficiency was also high. In addition, the exothermic start temperature in the thermal analysis of the de-Li sample was as high as 210 ° C., and it was found that the thermal stability was excellent.

  Similarly, in the following examples and comparative examples, the production conditions and powder characteristics of nickel hydroxide particle powder are shown in Table 1, and the firing temperature of the positive electrode active material particle powder of lithium nickel oxide produced using the same Table 2 shows the powder characteristics and battery characteristics.

[Examples 2-1, 3-1, 4-1]
When producing the nickel hydroxide particle powder, the other steps were performed in the same manner as in Example 1-1, except that the nickel raw material dropping rate, the neutralized excess NaOH concentration, and the reaction time were changed according to the production conditions shown in Table 1. As a result of Example 2-1, as shown in FIG. 5, dense nickel hydroxide particle powder having a large primary particle diameter was obtained. As shown in Table 1, low specific surface area, large crystallite size, moderate agglomerated particle size and narrow agglomerated particle size distribution, low residual sulfur S content are obtained, and good powder characteristics showing high tap density are obtained. It was.

[Examples 2-2, 3-2, 4-2]
In Examples 2-2, 3-2, and 4-2, the nickel hydroxide particle powders obtained in Examples 2-1, 3-1, and 4-1, respectively, were used. In the same manner as in Example 1-2, 150 g of each nickel hydroxide particle powder was weighed, and lithium hydroxide LiOH.H ₂ O was weighed so that the ratio Li / Ni = 1.05 mol. Using a desktop mixer having stirring blades, after dry mixing, it was fired at 860 ° C. for 10 hours in an oxygen atmosphere. Then, while pulverizing with a mortar, classification was performed using a sieve having an opening of 45 μm.

As shown in Table 2, the obtained positive electrode active material particle powder of lithium nickel oxide has a large primary particle diameter, a low Ni ²⁺ ion content, a small specific surface area, and an agglomerated particle of nickel hydroxide particle powder. Excellent powder characteristics with little change in diameter and narrow particle size distribution were obtained. The molded body density was 3.3 g / cc or more and was high.

  As the battery characteristics of the obtained positive electrode active material particle powder, as shown in Table 2, it had a high capacity, a high heat generation starting temperature, and excellent thermal stability.

[Example 5-1]
The production of the nickel hydroxide particle powder was performed under the same conditions as in Example 2 except for the nickel raw material dropping speed. For 19 hours from the start of the dropping, the raw material was gradually dropped into the reaction mother liquor at a rate of 0.025 [mol / (L · hr)] so that no new crystal nuclei were generated during the dropping. The remaining 71 hours were added dropwise at a rate of 0.05 [mol / (L · hr)]. As shown in Table 1, the powder characteristics of the obtained nickel hydroxide particle powder showed a large aggregated particle diameter of 20.1 μm.

[Example 5-2]
Based on the obtained nickel hydroxide particle powder, a positive electrode active material particle powder of lithium nickel oxide was produced in the same manner as in Example 1. The properties of the particle powder are shown in Table 2.

[Examples 6-1 and 6-2]
This was performed under the same conditions as in Example 4-1, except that magnesium sulfate was used as the Mg raw material and a solution having a Ni / Mg = 0.98 / 0.02 mol ratio was used as the raw material solution. Based on the conditions of Example 1-2, the molar ratio was Li / (Ni + Mg) = 1.05. The powder characteristics of the obtained nickel hydroxide particle powder are shown in Table 1, and the powder of the obtained positive electrode active material particle powder of lithium nickel oxide and the battery characteristics are shown in Table 2.

[Comparative Examples 1-1 to 4-1]
According to the numerical values described in Table 1, the nickel raw material dropping rate, NH ₄ OH concentration, neutralized surplus NaOH concentration, reaction temperature, and reaction time were changed, and other conditions were hydroxylated under the same conditions as in Example 1-1. Nickel particle powder was produced. FIG. 6 shows SEM photographs of the nickel hydroxide particles obtained in Comparative Examples 1-1 and 2-1, and Table 1 shows the powder characteristics. The obtained nickel hydroxide particle powder was not dense, the specific surface area was high, and the crystallite size was small. In Comparative Examples 1-1 and 2-1, the amount of residual sulfur S was also large. In Comparative Examples 3-1 and _4-1, the _{(D 84 -D 16) / D} 50 high, had spread particle size distribution. Also from the SEM photograph of the particle cross section of FIG. 7, there was no appearance that the particles were densely packed, and many of the obtained tap densities were low.

[Comparative Examples 1-2, 2-2, 3-2]
Using the nickel hydroxide particle powder obtained in Comparative Examples 1-1, 2-1, and 3-1, Li was formed as Comparative Examples 1-2, 2-2, and 3-2, respectively. In the same manner as in Example 1-2, 150 g of the nickel hydroxide particle powder was weighed, and lithium hydroxide LiOH.H ₂ O was charged and weighed so that the ratio Li / Ni = 1.05 mol. Using a desktop mixer having stirring blades, after dry mixing, it was fired at 860 ° C. for 10 hours in an oxygen atmosphere. Then, while pulverizing with a mortar, classification was performed using a sieve having an opening of 45 μm.

As shown in Table 2, the obtained positive electrode active material particle powder of lithium nickel oxide was expected to have few structural defects because the amount of Ni ²⁺ ions was small, and the compact density was high. On the other hand, the primary particle size was as small as 1 μm, and the specific surface area was relatively high. A wide particle size distribution was also obtained, and it was difficult to say that the powder characteristics were excellent. Although the discharge capacity is high, the heat generation start temperature by DSC of the sample in the Li-free state is low, and when it is used for a secondary battery, heat generation is expected to start at a low temperature, which is said to be excellent in thermal stability. It was difficult.

[Comparative Examples 4-2a and 4-2b]
Using the nickel hydroxide particle powder obtained in Comparative Example 4-1, a mixture with a Li raw material was produced in the same manner as in Example 1-2. Comparative Example 4-2a was fired in an oxygen atmosphere at 950 ° C.-10 h, and Comparative Example 4-2b was 1000 ° C.-10 h. Then, while pulverizing with a mortar, classification was performed using a sieve having an opening of 45 μm.

As shown in Table 2, the obtained positive electrode active material particle powder of lithium nickel oxide had a large primary particle diameter and a small specific surface area, but contained a large amount of Ni ²⁺ ions. The particle size distribution also spreads and gets worse, and some have a low molded body density. Although the exothermic start temperature by DSC of the sample in the Li-free state was high, the battery characteristics were extremely deteriorated.

  The nickel hydroxide particle powder according to the present invention has a small specific surface area and a large crystallite size. In addition, the aggregated particle diameter is uniform, dense and excellent in filling properties. Since the positive electrode active material particle powder of the lithium nickel oxide according to the present invention can also use the nickel hydroxide particle powder obtained in the present invention as a precursor, the resulting primary particle size is large, the filling property is excellent, and Excellent thermal stability in delithiated state. Therefore, a secondary battery having high energy density and excellent thermal stability can be manufactured.

  Since the present invention has a small specific surface area and a large crystallite size, it is possible to obtain a nickel hydroxide particle powder exhibiting a high filling property at a low cost by a production method with a small environmental load. The positive electrode active material particle powder of lithium nickel oxide, which can also be produced as a precursor, has a large primary particle size and few structural defects. Therefore, the non-aqueous electrolyte secondary battery using the positive electrode active material particle powder as a positive electrode has a high energy density and excellent thermal stability.

Claims (10)

The BET specific surface area is 0.5 to 8.0 m ² / g, the crystallite size perpendicular to the (00l) plane is 20 to 100 nm, and the crystallite size parallel to the (00l) plane is 40 to 300 nm. Characteristic nickel hydroxide particle powder. The median diameter (D ₅₀ ) of the volume-based aggregated particles is 5 to 30 μm, and the ratio (D ₈₄ -D ₁₆ ) between the median diameter D ₅₀ and the peak width (D ₈₄ -D ₁₆ ) in the particle size frequency distribution. ) _/ nickel hydroxide particles of claim 1 _{D 50} is 0.4 or less.   The nickel hydroxide particle powder according to claim 1 or 2, wherein the content of impurity sulfur S is 0.15 wt% or less.   The nickel hydroxide particle powder according to any one of claims 1 to 3, wherein at least one of Mg, Co, and Al is substituted with a part of Ni.   The nickel raw material, complexing agent, and neutralizing agent are continuously dropped into a reactor equipped with a draft tube and a stirrer, and solid-liquid separation is performed by a concentrator, so that the mother liquor volume in the reactor is kept constant and the reaction is performed. The nickel raw material dropping rate into the mother liquor is 0.02 to 0.25 [mol / (L · hr)], the concentration of the complexing agent is 0.3 to 1.5 mol / L, and the concentration of the surplus of the neutralizing agent The nickel hydroxide particles according to claim 1, wherein 0.02 to 0.5 mol / L, reaction temperature is 45 to 80 ° C., and reaction time is 40 to 300 hours. Powder manufacturing method.   6. The method for producing nickel hydroxide particle powder according to claim 5, wherein the nickel raw material is at least one of nickel sulfate and nickel chloride, and the complexing agent is at least one of ammonia water, ammonium sulfate and ammonium chloride. The method for producing nickel hydroxide particle powder, wherein the neutralizing agent is at least one of sodium hydroxide, sodium carbonate, or potassium hydroxide.   The manufacturing method of the positive electrode active material particle powder of the lithium nickel oxide baked at the temperature of 600-930 degreeC after mixing with a lithium raw material using the nickel hydroxide particle powder as described in any one of Claims 1-4. Positive electrode active of lithium nickel oxide, characterized in that the primary particle size is 2 to 15 μm, the amount of Ni ²⁺ ions relative to the total nickel amount is 10 mol% or less, and the BET specific surface area is 0.05 to 0.35 m ² / g. Substance particle powder. The median diameter D ₅₀ of the aggregated particles is 5 to 30 μm, and the ratio (D ₈₄ −D ₁₆ ) / D _{50 of the} median diameter D ₅₀ to the peak width (D ₈₄ −D ₁₆ ) in the particle size frequency distribution is 0. The positive electrode active material particle powder of lithium nickel oxide according to claim 8, which is .6 or less.   A non-aqueous electrolyte secondary battery using the positive electrode active material particle powder of lithium nickel oxide according to claim 8 or 9 as at least a part of the positive electrode active material.