JP2002255562A - Method for manufacturing positive electrode active material for alkali secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a positive electrode active material for an alkali secondary battery by solving problems of conventional methods requiring relatively large air heating device or microwave irradiation device which consumes much energy pushing up production cost. SOLUTION: This method for manufacturing the positive electrode active material for the alkali secondary battery comprises the steps of (a) introducing steam into a jacket of a vertical high speed mixing and pelletizing device with a jacket provided with an air inlet and a vent on the upper lid, and heating inside of the body at 50 to 130 deg.C, (b) starting agitation on charging nickel hydroxide particles coated with α-cobalt hydroxide while continuing introduction of steam into the jacket, and heating the nickel hydroxide particles coated with the α-cobalt hydroxide at 40 to 120 deg.C, (c) spraying an alkali metal hydroxide aqueous solution onto the α-cobalt hydroxide coated nickel hydroxide particles while continuing agitation to conglobating the particle, and (d) starting exhaustion and introducing air into inside of the device wile continuing agitation and introduction of steam into the jacket to high order oxidize the α-cobalt hydroxide into γ-cobalt oxyhydroxide and drying the particles, and is characterized in that an auxiliary heating by microwave is not used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a positive electrode active material for an alkaline secondary battery, and more particularly to nickel hydroxide particles having a high-order cobalt oxyhydroxide (.gamma.-cobalt oxyhydroxide) coating. And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, an alkaline secondary battery using an active material mainly composed of nickel hydroxide for a positive electrode, for example, a nickel-cadmium battery or a nickel-hydrogen battery has been frequently used. Particularly in recent years, as a power source for portable electronic devices such as mobile phones and portable audio devices, a non-sintered material in which a powdery active material is filled in a base such as foamed nickel or is made into a paste and supported on a punching metal or the like. A nickel electrode of a mold type has been widely used because a packing density of an active material is higher than that of a conventional sintered nickel electrode and high capacity can be expected. However, various proposals have been made to further improve the utilization rate of a highly-filled active material for the purpose of further increasing the capacity of a non-sintered nickel electrode.

[0003] JP-A-8-148145 discloses an active material composed of granular nickel hydroxide having cobalt and / or a cobalt compound unevenly distributed on the surface thereof, and a suspension in which a cobalt compound solution contains granular nickel hydroxide. Discloses a method for producing an active material in which cobalt hydroxide is precipitated with granular nickel hydroxide as a nucleus by adding alkali to the mixture and further heated in the presence of an alkali metal hydroxide and oxygen to highly oxidize cobalt hydroxide. Have been.

Japanese Patent Application Laid-Open No. Hei 10-261414 discloses that a mixed particle of nickel hydroxide and cobalt hydroxide is treated with an alkali using a batch-type fluidized drying apparatus, a kneader and a Nauta mixer (trade name, manufactured by Hosokawa Micron Corporation). Japanese Patent Application Laid-Open No. 11-329425 and Japanese Patent Application Laid-Open No. 11-9700 disclose an alkaline heat treatment method for directly heating particles by introducing an aqueous metal solution and heated air to highly oxidize cobalt hydroxide.
No. 8 discloses a method of using direct heating by microwave irradiation for alkali heat treatment.

[0005]

In each of the above-mentioned methods, a large amount of air is introduced into the apparatus in order to fluidize the granules in the apparatus and prevent their fusion, and the entire amount is reduced to the reaction temperature. Heating. As a result, a relatively large air heating device or microwave irradiation device is required, the energy consumption is large, and the production cost of the positive electrode active material is increased.

An object of the present invention is to provide an improved method for producing a positive electrode active material for an alkaline secondary battery.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, have found an apparatus provided with an air inlet at the periphery of an exhaust port of a vertical high-speed mixing and granulating apparatus with a jacket. As a result of conducting high-order oxidation of cobalt hydroxide using only indirect heating from the jacket, it was found that a cathode material having the same physical properties as in the case of employing a direct heating method using a batch-type fluidized drying apparatus was obtained. Completed the invention.

According to the present invention, (a) steam is introduced into a jacket of a vertical type high-speed mixing and granulating apparatus equipped with a jacket provided with an air inlet and an air outlet in an upper lid, and the inside of the main body is heated to 50 to 13 mm.
Heating to 0 ° C., (b) while continuing to introduce water vapor into the jacket, add α-cobalt hydroxide-coated nickel hydroxide particles into the main body and start stirring, and α-cobalt hydroxide-coated. Heating the deposited nickel hydroxide particles to 40 to 120 ° C., (c) continuing to stir while spraying the aqueous alkali metal hydroxide solution onto the α-cobalt hydroxide coated nickel hydroxide particles from a spray nozzle. And (d) continuing to stir and introduce water vapor into the jacket while initiating evacuation and introducing air into the apparatus to convert α-cobalt hydroxide into γ-cobalt oxyhydroxide. A process for oxidizing and drying the particles, wherein no auxiliary heating by microwave is used.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of a vertical high-speed mixing granulator used in the production of a cathode active material for an alkaline secondary battery according to the present invention will be described with reference to FIG. Vertical high-speed mixing granulator 1
Is composed of a container body 2 having an upper lid, a flat bottom, and a cylindrical body, a stirrer 3 for granular material, and a body heating jacket 4 provided on the outer periphery of the flat bottom 2b and the cylindrical body 2c of the container body 2. You.

In the upper cover of the main body, a raw material inlet 5, a liquid spray nozzle 6, and an exhaust port 7 are arranged, and at least one air inlet 8 is provided. The exhaust port 7 is connected to an exhaust blower via a filter (not shown).
A temperature detection nozzle and a pressure gauge nozzle (not shown) are further arranged on the upper lid.

The bottom of the container body 2 is usually a flat bottom, depending on the shape of the stirring blade. The cylindrical body may be a vertical cylinder from the bottom to a certain height, and the upper part may be constituted by a conical or inverted conical body.

The agitator 3 for powders and granules is generally provided with S-shaped, rod-type, anchor-type, etc. stirring blades used for mixing and granulating the powders and granules, and is provided with a stirring shaft and a speed reducer. Connected to the motor. The stirrer seat may be provided on either the top lid or the flat bottom. A chopper 9 is arranged in the container body 2. The main body heating jacket 3 includes a heating steam inlet, a drain port, and a pressure detection nozzle and a pressure gauge nozzle (not shown).

In the present invention, a vertical high-speed mixing granulator 1
In a commercially available vertical high-speed mixing and granulating apparatus with a jacket, the exhaust port 7 and at least one air inlet 8 can be installed on the upper lid of the main body and used. The air inlet 8 may be provided with a plurality of pores around the outlet 7 of the upper cover of the main body as shown in FIG.

By installing the air inlet 8 on the upper lid of the main body,
Most of the air introduced from the air inlet 8 at the time of exhaust is exhausted together with the reaction gas without being heated, and only the air necessary for the reaction circulates in the main body. As a result, the reaction is required only by heating from the jacket 3. Heat can be sufficiently supplied.

The method for producing a positive electrode active material for an alkaline secondary battery according to the present invention uses the above-described vertical high-speed mixing granulator with a jacket. In the step (a), steam is introduced into the jacket 3 and the inside of the container body 2 is heated to 50 to 130 ° C, preferably 70 to 120 ° C, more preferably 80 to 100 ° C.
Heat to ° C. If the heating temperature inside the main body is too low, the heating time in the subsequent step (b) becomes too long, and heating to an unnecessarily high temperature is not preferred because the raw material charging operation in the subsequent step (b) involves danger.

In the subsequent step (b), while the introduction of steam into the jacket 3 is continued, α-
The cobalt hydroxide-coated nickel hydroxide particles are charged and stirring is started, and the α-cobalt hydroxide-coated nickel hydroxide particles are heated to 40 to 120 ° C, preferably 60 to 110 ° C, more preferably 80 to 100 ° C. Heat.

Instead of using a mixture of α-cobalt hydroxide particles and nickel hydroxide particles as a raw material, an aqueous slurry containing nickel hydroxide particles is dissolved by adding a cobalt salt, for example, cobalt sulfate, Is added to adjust the pH to 10.5 to 11.5 to generate α-cobalt hydroxide crystals with nickel hydroxide particles as nuclei, and to adhere to the surface of the nickel hydroxide particles, so-called wet neutralization. Α-Cobalt hydroxide-coated nickel hydroxide particles produced by the method are used.

The heating temperature is preferably higher in consideration of the reaction and the drying rate in the subsequent step (c) and subsequent steps, but may be at least a certain temperature. Heating to an unnecessarily high temperature may reduce the vapor pressure of steam for heating. It is not preferable because it is required to be high.

In the step (c), the aqueous alkali metal hydroxide solution is sprayed from the spray nozzle 6 while maintaining stirring.
Spraying onto cobalt hydroxide coated nickel hydroxide particles. By this operation, the α adhered to the nickel hydroxide particles
-Cobalt hydroxide adsorbs the alkali metal aqueous solution and gels, forming a coating on the surface of the nickel hydroxide particles. Further, the particles are pulverized and dispersed by the chopper 9 into individual particles, and are spheroidized into a shape close to a true sphere.

As the aqueous solution of the alkali metal hydroxide, an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide and the like can be used, preferably an aqueous solution of sodium hydroxide having a high concentration of 32% or more, more preferably an aqueous solution of sodium hydroxide of 48% or more. I do. If the concentration of the aqueous alkali metal hydroxide solution is too low, the particles are partially dissolved to form lumps, and a large amount of water must be evaporated to obtain dry particles, which is not preferable.

In step (d), stirring is started and the introduction of water vapor into the jacket is continued while air is introduced into the apparatus by starting evacuation. Thereby, the α-cobalt hydroxide layer is highly oxidized by contact of the particles with air, and the particles are dried.

Following the step (d), a post-step of washing, dehydrating and drying the obtained particles is carried out, whereby
Dried positive electrode material particles for an alkaline secondary battery, that is, substantially spherical particles having nickel hydroxide as a nucleus and having a uniform γ-cobalt oxyhydroxide layer on the surface are obtained.

As shown in Table 1, the cathode material particles for an alkaline secondary battery obtained by the above method have the same physical properties as the cathode material particles obtained by a conventional batch flow method.

[0024]

[Table 1]

[0025]

EXAMPLES The present invention will be described in more detail with reference to Examples. The measurement methods used in the examples are summarized below.

(TAP density, BULK density): Measured according to the following procedure. The measuring instrument is SEISHIN TAPDE
NSER KYT3000 was used. The measurement powder is naturally dropped and filled into a 20 ml cell with a 48 mesh sieve. KYT30
Tap 200 times at 00 and measure the fill volume. TAP density = filling amount (g) / filling volume (ml) BULK density = filling amount (g) / 20 (cell volume) (ml)

(Average particle size): Measured according to the following procedure. Laser particle size analyzer (PRO-7000S manufactured by Seisin)
And set a blank measurement. Add 2 to 3 drops of surfactant (extran) to the ultrasonic dispersion tank. A few ml sample is charged and the particle size distribution is measured while performing ultrasonic dispersion. The diameter equivalent to 50% by weight is read as the average particle diameter.

(Half width (101)): Measured according to the following procedure. A measuring powder is applied to the measuring cell. The half width at 38.4 ° is measured with an X-ray diffractometer (XD-D1 manufactured by Shimadzu). Measurement conditions Target: Cu, tube voltage: 40 kV, tube current: 30 m
A, divergence slit: 1 deg., Scattering slit: 1 deg., Light receiving slit: 0.3 mm, scanning axis: θ-2θ, scanning range: 30-45 deg., Scanning mode: continuous, scanning speed: 2
deg./min, sampling width: 0.043 deg., preset time: 0.4 sec., full scale: 2.0 kcps. Processing conditions Smoothing points: 17 points, background removal: automatic, K
α1-Kα2 separation: execution

(Resistance value): The resistance value is measured according to the following procedure. 5 g of sample is weighed to the nearest 0.1 g,
Place in a 0 mm, 3 mm height vinyl chloride cylinder. A pressure of 100 kN is applied from both ends of the cylinder by a press machine, and the obtained pellet-shaped sample is further sandwiched between SUS cylinders and a pressure of 100 kN is applied. The resistance value between the active materials is measured using a digital multimeter.

Example 1 Apparatus: A manufacturing apparatus 1 having a main body heating jacket 4 having the structure shown in FIG. 1 was prepared. The basic specifications of this device are as follows.

The jacket 4 of the above-mentioned manufacturing apparatus 1
g / cm ² G (110 ° C.) to supply saturated steam
Was heated, and when the internal temperature reached 80 ° C., 80 kg of spherical cobalt hydroxide-coated nickel hydroxide particles were charged. The stirrer was started to start stirring at a rotation speed of 250 rpm, and the supply of saturated steam to the jacket 3 was continued, and the internal temperature was raised to 80 ° C. in about 10 minutes. At the time when the internal temperature reaches 80 ° C., the above stirring is continued and the 48% aqueous sodium hydroxide solution 7.5 k is sprayed from the spray nozzle 6.
g was fed in about 2 minutes to evenly coat the elevated temperature cobalt hydroxide coated nickel hydroxide particles. After the entire amount of the sodium hydroxide aqueous solution is supplied, the exhaust is started, and while the air is introduced from the air inlet 8 into the container body, the rotation speed of the stirrer is reduced to 220 rpm, and the stirring is continued. The temperature inside the main body was maintained at a constant temperature of 80 ° C., and water in the main body was evaporated to obtain dry particles in about 30 minutes. The obtained dried particles were poured into water and stirred to dissolve impurities such as adhered alkalis in water, then the particles were settled and the supernatant liquid was decanted. Next, the sedimented particles are dehydrated using a press to collect a cake containing about 10% of water, and the cake is dried using a hot air drier until the water content becomes 1% or less. Thus, nickel hydroxide particles coated with cobalt hydroxide oxide were obtained. Various properties of the obtained particles are shown in Table 2 together with the properties of the raw material particles and the properties of the particles produced using a conventional batch-type fluidized-bed dryer.

[0032]

[Table 2]

As shown in Table 2, the cathode material particles obtained using the apparatus and method of the present invention have particle properties, particularly TAP density, comparable to those obtained by the conventional method. In addition, the amount of steam consumed per product required for the reaction was about half that of the conventional method in which particles were fluidized by heated air.

[0034]

According to the present invention, since the flow of particles in the apparatus main body depends on the stirring force and does not require heating of a large amount of air, the energy consumption is small, and there is no need to use auxiliary heating by microwaves. Lower manufacturing costs. The present invention provides an inexpensive method for producing a cathode material for an alkaline battery, and its industrial significance is extremely large.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a vertical high-speed mixing granulator used in the present invention.

[Explanation of symbols]

 1: Vertical high-speed mixing granulator 2: Container body 3: Stirrer 4: Body heating jacket 5: Raw material input port 6: Spray nozzle 7: Exhaust port 8: Air inlet 9: Chopper

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tokuyoshi Iida 45-10, Shirahama-cho, Fukui-shi, Fukui Prefecture 5-10, Sunahamawari F-term in Tanaka Chemical Laboratory Co., Ltd. 4G048 AA03 AB01 AB05 AC06 AD04 AE05 5H050 AA19 BA11 CA03 CA04 FA17 FA18 GA02 GA10 GA21 GA27 GA29 HA01 HA14

Claims (3)

[Claims] 1. A step of introducing steam into a jacket of a vertical high-speed mixing and granulating apparatus equipped with a jacket provided with an air inlet and an air outlet in an upper lid, and heating the inside of the main body to 50 to 130 ° C., (b) ) While continuing to introduce steam into the jacket,
A step of introducing α-cobalt hydroxide-coated nickel hydroxide particles into the body, starting stirring, and heating the α-cobalt hydroxide-coated nickel hydroxide particles to 40 to 120 ° C., (c) from a spray nozzle A step of spraying an aqueous solution of an alkali metal hydroxide onto the α-cobalt hydroxide-coated nickel hydroxide particles while continuing to stir the particles, and (d) starting exhaust and introducing air into the apparatus While continuing stirring and introducing steam into the jacket, α-
A method for highly oxidizing cobalt hydroxide to γ-cobalt oxyhydroxide and drying the particles, wherein no auxiliary heating by microwave is used, and a method for producing a cathode material for an alkaline secondary battery. 2. The raw material α-cobalt hydroxide-coated nickel hydroxide particles are particles having nickel hydroxide particles obtained by a wet neutralization method as nuclei and having α-cobalt hydroxide adhered to the surface thereof. The method of claim 1 wherein: 3. The method according to claim 1, wherein the alkali metal hydroxide aqueous solution sprayed in the step (c) is a 32-48% sodium hydroxide aqueous solution.