JP4737849B2 - Method for producing positive electrode active material for alkaline secondary battery - Google Patents

Description

【００２５】
【実施例】
本発明を実施例によりさらに詳細に説明する。
なお、実施例で使用した各測定方法は以下にまとめた。
【００２６】
(ＴＡＰ密度、ＢＵＬＫ密度)：以下の手順で測定した。
測定機器は、ＳＥＩＳＨＩＮ ＴＡＰＤＥＮＳＥＲ ＫＹＴ３０００を用いた。
４８meshのふるいで測定粉を２０mlセルに自然落下充填する。ＫＹＴ３０００で２００回タッピングし、充填体積を測定する。
ＴＡＰ密度 ＝ 充填量（ｇ）／充填体積(ml)
ＢＵＬＫ密度 ＝ 充填量（ｇ）／２０（セル体積）(ml)
【００２７】
(平均粒径）：以下の手順で測定した。
レーザー粒度分析計（セイシン製 ＰＲＯ−７０００Ｓ）をセットしてブランク測定する。超音波分散槽に界面活性剤（エキストラン）２〜３滴添加する。数mlサンプルを投入し、超音波分散を行いながら粒度分布を測定する。重量５０％相当径を平均粒径として読み取る。
【００２８】
(半値幅（１０１）)：以下の手順で測定した。
測定用セルに測定紛を塗布する。Ｘ線回折装置（島津製ＸＤ−Ｄ１）にて３８.４°での半値幅を測定する。
測定条件
ターゲット：Ｃｕ、管電圧：４０ｋＶ、管電流：３０ｍＡ、発散スリット： １deg.、散乱スリット：１deg.、受光スリット：０.３ｍｍ、走査軸：θ−２θ、走査範囲：３０〜４５deg.、走査モード：連続、走査速度：２deg.／min、サンプリング幅：０.０４３deg.、プリセット時間：０.４sec.、フルスケール：２.０kcps.
処理条件
平滑化点数：１７点、バックグラウンド除去：自動、Ｋα１−Ｋα２分離：
実行
【００２９】
(抵抗値）：抵抗値は以下の手順で測定する。
サンプル５ｇを０.１ｇの単位まで秤量し、内径３０ｍｍ、高さ３ｍｍの塩化ビニル製円筒に入れる。プレス機で上記円筒の両端から１００ｋＮの圧力をかけ、得られるペレット状のサンプルを更にＳＵＳ製円筒で挟み１００ｋＮの圧力をかける。これをデジタルマルチメータを使用して活物質間抵抗値を測定する。
【００３０】
実施例 １
装置：図１に示す構造の本体加熱用ジャケット４を備えた製造装置１を準備した。この装置の基本仕様は下記の通りである。

【００３１】
上記製造装置１のジャケット４に、０.４kg／cm²Ｇ（１１０℃）の飽和蒸気を供給して本体容器２の内部を加熱し、内部温度が８０℃に達した時点に球状水酸化コバルト被着水酸化ニッケル粒子８０ｋｇを投入した。撹拌機を起動して回転数２５０ｒｐｍで撹拌を開始し、ジャケット３への飽和水蒸気の供給を継続して約１０分間で内部温度を８０℃まで加温した。
内部温度が８０℃に達した時点に、上記撹拌を継続しながらスプレーノズル６から４８％水酸化ナトリウム水溶液７.５ｋｇを約２分間で供給して、温度の上昇した水酸化コバルト被着水酸化ニッケル粒子上に満遍なくコーティングした。
水酸化ナトリウム水溶液の全量を供給した後、排気を開始し、それに伴って空気導入口８から空気を容器本体内に導入しながら、撹拌機の回転数を２２０ｒｐｍに低下させて撹拌を継続し、本体内温度を８０℃の一定温度に維持し、本体内の水分を蒸発させ、約３０分で乾燥粒子を得た。
得られた乾燥粒子を、水中に投入、撹拌して付着しているアルカリ分などの不純物を水中に溶解させた後、粒子を沈降させ上澄み液をデカントした。次いで沈降した粒子をプレスを用いて脱水し約１０％の水分を含有するケーキを回収し、このケーキを熱風乾燥機を使用して水分含有率が１％以下になるまで乾燥し、目的の高次酸化水酸化コバルト被覆水酸化ニッケル粒子を得た。
得られた粒子の諸特性を、原料粒子の特性および従来の回分式流動乾燥装置を使用して製造した粒子の特性と共に表２中に示す。
【００３２】
【表２】

【００３３】
表２に示したように、本発明の装置および方法を用いて得られた正極物質粒子は、従来法で得られた粒子に匹敵する粒子特性、特にＴＡＰ密度を有している。また、反応に要した製品当たりの蒸気消費量は加熱空気により粒子を流動化させる従来法の約１／２であった。
【００３４】
【発明の効果】
本発明は、装置本体内における粒子の流動を撹拌力に依存し大量の空気の加熱を必要としないので消費エネルギーが小さく、マイクロ波による補助加熱を使用する必要がなく正極物質の製造コスト低下させる。
本発明は、アルカリ電池用正極物質の安価な製造方法を提供するものであり、その産業的意義はきわめて大きい。
【図面の簡単な説明】
【図１】本発明で使用する縦型高速混合造粒装置の一態様を示す断面図である。
【符号の説明】
１：縦型高速混合造粒装置
２：容器本体
３：撹拌機
４：本体加熱用ジャケット
５：原料投入口
６：スプレーノズル
７：排気口
８：空気導入口
９：チョッパー[0001]
BACKGROUND 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 a method for producing nickel hydroxide particles having a high-order cobalt oxide hydroxide (γ-cobalt oxyhydroxide) coating.
[0002]
[Prior art]
Conventionally, an alkaline secondary battery using an active material mainly composed of nickel hydroxide as 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, non-sintered powdery active material filled in a base material such as foamed nickel or carried in punched metal or the like in paste form The type of nickel electrode is increasingly used because it has a higher packing density of the active material and can be expected to have a higher capacity than a conventional sintered type nickel electrode. However, various proposals have been made to further improve the utilization rate of the highly filled active material in order to achieve a further increase in capacity of the non-sintered nickel electrode.
[0003]
Japanese Patent Application Laid-Open No. 8-148145 discloses an active material composed of granular nickel hydroxide in which cobalt and / or a cobalt compound is unevenly distributed on the surface, and a suspension in which granular nickel hydroxide is contained in a cobalt compound solution. A method for producing an active material is disclosed in which cobalt hydroxide is precipitated by adding granular nickel hydroxide as a nucleus, and further heated in the presence of an alkali metal hydroxide and oxygen to highly oxidize cobalt hydroxide. .
[0004]
JP-A-10-261414 uses a batch fluid dryer, a kneader and a Nauta mixer (trade name, manufactured by Hosokawa Micron Co., Ltd.), and an alkali metal aqueous solution and a mixed particle of nickel hydroxide and cobalt hydroxide. JP-A-11-329425 and JP-A-11-97008 disclose an alkali heat treatment method in which heated air is introduced to directly heat particles to highly oxidize cobalt hydroxide. A method of using heating is disclosed.
[0005]
[Problems to be solved by the invention]
In each of the above-described methods, a large amount of air is introduced into the apparatus in order to fluidize the powder particles in the apparatus and prevent their fusion, and the entire amount is heated to the reaction temperature. As a result, a relatively large air heating device or microwave irradiation device is required, the amount of energy consumption is large, and the manufacturing cost of the positive electrode active material is increased.
[0006]
An object of this invention is to provide the improved manufacturing method of the positive electrode active material for alkaline secondary batteries.
[0007]
[Means for Solving the Problems]
As a result of diligent research to achieve the above object, the present inventors have used a device in which an air inlet is provided in the periphery of the exhaust port of a jacketed high-speed mixing granulator, and uses cobalt oxide for higher-order oxidation of cobalt hydroxide. As a result of carrying out the process only by indirect heating from the jacket, it was found that a positive electrode material having physical properties equivalent to those obtained when the direct heating method using a batch fluidized drying apparatus was adopted was completed.
[0008]
The present invention
(A) introducing water vapor into a jacket of a jacketed vertical high-speed mixing granulator provided with an air inlet and an exhaust port on the upper lid, and heating the inside of the main body to 50 to 130 ° C;
(B) While continuing the introduction of water vapor into the jacket, the α-cobalt hydroxide-deposited nickel hydroxide particles were introduced into the main body and stirring was started. Heating to ~ 120 ° C,
(C) A step of spheroidizing the particles by continuing stirring while spraying the alkali metal hydroxide aqueous solution onto the α-cobalt hydroxide-deposited nickel hydroxide particles from the spray nozzle, and (d) starting the exhaust. Continuing stirring and introduction of water vapor into the jacket while introducing air into the apparatus, subjecting α-cobalt hydroxide to higher oxidation to γ-cobalt oxyhydroxide and drying the particles;
And a method for producing a positive electrode material for an alkaline secondary battery, wherein auxiliary heating by microwaves is not used.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a vertical high-speed mixing granulator used in the production of a positive electrode active material for an alkaline secondary battery according to the present invention will be described with reference to FIG.
A vertical high-speed mixing granulator 1 is provided on the outer periphery of a container body 2 composed of an upper lid, a flat bottom, and a cylindrical body, a powder agitator 3 and a flat bottom 2b of the container body 2, and a cylindrical body 2c. Consists of a body heating jacket 4.
[0010]
A raw material charging port 5, a liquid spray nozzle 6 and an exhaust port 7 are disposed on the upper lid of the main body, and at least one air introduction port 8 is further provided. The exhaust port 7 is connected to an exhaust blower through a filter (not shown). Further, a temperature detection nozzle and a pressure gauge nozzle (not shown) are arranged on the upper lid.
[0011]
The bottom of the container body 2 is usually a flat bottom although it depends 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.
[0012]
The granular material agitator 3 is generally equipped with S-shaped, rod-shaped, anchor-shaped, etc. agitation blades used for mixing and granulating granular materials, and is connected to an electric motor via a stirring shaft and a speed reducer. Connected. The stirrer seat may be provided on either the upper lid or the flat bottom. A chopper 9 is disposed 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).
[0013]
In the present invention, the vertical high-speed mixing and granulating apparatus 1 is installed in a jacket-type vertical high-speed mixing and granulating apparatus that is generally available on the body upper cover of the exhaust port 7 and at least one air introduction port 8. can do. As shown in FIG. 1, the air introduction port 8 may have a plurality of fine holes arranged around the exhaust port 7 of the upper lid of the main body.
[0014]
As a result of the installation of the air inlet 8 on the top lid of the main body, most of the air introduced from the air inlet 8 during exhaust is exhausted together with the reaction gas without being heated, and only the air necessary for the reaction circulates in the main body. Heat required for the reaction can be sufficiently supplied only by heating from the jacket 3.
[0015]
The manufacturing method of the positive electrode active material for alkaline secondary batteries of the present invention uses the above-mentioned jacketed vertical high-speed mixing granulator.
In the step (a), water vapor is introduced into the jacket 3 to heat the inside of the container body 2 to 50 to 130 ° C., preferably 70 to 120 ° C., more preferably 80 to 100 ° 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 preferable because it involves danger in the raw material charging operation in the subsequent step (b).
[0016]
In the subsequent step (b), while continuing the introduction of water vapor into the jacket 3, the α-cobalt hydroxide-deposited nickel hydroxide particles are introduced from the raw material inlet 3 and stirring is started. The nickel hydroxide particles are heated to 40 to 120 ° C, preferably 60 to 110 ° C, more preferably 80 to 100 ° C.
[0017]
Rather than using a mixture of α-cobalt hydroxide particles and nickel hydroxide particles as a raw material, a cobalt salt such as cobalt sulfate is dissolved in an aqueous slurry containing nickel hydroxide particles, and then alkali is added. By adjusting the pH to 10.5 to 11.5, α-cobalt hydroxide crystals are produced using nickel hydroxide particles as nuclei and deposited on the surface of the nickel hydroxide particles. Α-cobalt hydroxide-coated nickel hydroxide particles are used.
[0018]
The heating temperature is preferably higher in consideration of the reaction and the drying rate in the subsequent step (c), but may be higher than a certain temperature, and heating to a higher temperature than necessary should increase the vapor pressure of the steam for heating. Is not preferable.
[0019]
In the step (c), an alkali metal hydroxide aqueous solution is sprayed from the spray nozzle 6 onto the α-cobalt hydroxide-coated nickel hydroxide particles while stirring is continued. By this operation, the α-cobalt hydroxide deposited on the nickel hydroxide particles adsorbs the alkali metal aqueous solution and gels, thereby forming a coating on the surface of the nickel hydroxide particles. Further, the chopper 9 pulverizes and disperses the particles into individual particles and spheroidizes them into a shape close to a true sphere.
[0020]
As the alkali metal hydroxide aqueous solution, a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, or the like can be used, preferably a high concentration sodium hydroxide aqueous solution of 32% or more, more preferably 48% or more. If the concentration of the alkali metal hydroxide aqueous solution is too low, the particles are partially dissolved to form a lump, and a large amount of water must be evaporated to obtain dry particles, which is not preferable.
[0021]
In step (d), evacuation is started and air is introduced into the apparatus while stirring and introduction of water vapor into the jacket are continued. Thereby, the α-cobalt hydroxide layer is highly oxidized by contact of the particles with air, and the particles are dried.
[0022]
Subsequent to the step (d), the obtained particles are washed with water, dehydrated and dried, and then subjected to a post-process, whereby the dried positive electrode material particles for the alkaline secondary battery, that is, nickel hydroxide is used as a nucleus on the surface. Nearly spherical particles with a uniform γ-cobalt oxyhydroxide layer are obtained.
[0023]
As shown in Table 1, the positive electrode material particles for alkaline secondary batteries obtained by the above method have the same physical properties as the positive electrode material particles obtained by the conventional batch flow method.
[0024]
[Table 1]

[0025]
【Example】
The invention is explained in more detail by means of examples.
In addition, each measuring method used in the Example was summarized below.
[0026]
(TAP density, BULK density): Measured by the following procedure.
As a measuring instrument, SEISHIN TAPDENSER KYT3000 was used.
The measurement powder is naturally dropped and filled into a 20 ml cell with a 48 mesh sieve. Tapping 200 times with KYT3000 and measuring the filling volume.
TAP density = filling amount (g) / filling volume (ml)
BULK density = filling amount (g) / 20 (cell volume) (ml)
[0027]
(Average particle diameter): measured by the following procedure.
A laser particle size analyzer (PRO-7000S manufactured by Seishin) is set and blank measurement is performed. Add 2-3 drops of surfactant (Extran) to the ultrasonic dispersion tank. Add a few ml sample and measure the particle size distribution while ultrasonic dispersion. The diameter equivalent to 50% by weight is read as the average particle diameter.
[0028]
(Half-width (101)): Measured according to the following procedure.
Apply measurement powder to the measurement cell. The full width at half maximum 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 mA, divergence slit: 1 deg., Scattering slit: 1 deg., Light receiving slit: 0.3 mm, scanning axis: θ-2θ, scanning range: 30 to 45 deg., Scan mode: continuous, scan speed: 2 deg./min, sampling width: 0.043 deg., Preset time: 0.4 sec., Full scale: 2.0 kcps.
Processing conditions Number of smoothed points: 17 points, background removal: automatic, Kα1-Kα2 separation:
Execute [0029]
(Resistance value): The resistance value is measured by the following procedure.
A 5 g sample is weighed to the nearest 0.1 g and placed in a vinyl chloride cylinder having an inner diameter of 30 mm and a height of 3 mm. A pressure of 100 kN is applied from both ends of the cylinder with a press machine, and the obtained pellet-like sample is further sandwiched between SUS cylinders and a pressure of 100 kN is applied. The resistance value between active materials is measured for this using a digital multimeter.
[0030]
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.

[0031]
Saturated steam of 0.4 kg / cm ² G (110 ° C.) is supplied to the jacket 4 of the manufacturing apparatus 1 to heat the inside of the main body container 2, and when the internal temperature reaches 80 ° C., spherical cobalt hydroxide 80 kg of deposited nickel hydroxide particles were added. The stirrer was started and stirring was started at a rotational speed of 250 rpm. The supply of saturated steam to the jacket 3 was continued and the internal temperature was raised to 80 ° C. in about 10 minutes.
When the internal temperature reaches 80 ° C., while continuing the above stirring, 7.5 kg of 48% aqueous sodium hydroxide solution is supplied from the spray nozzle 6 in about 2 minutes to increase the temperature of the cobalt hydroxide-deposited hydroxide. Evenly coated on the nickel particles.
After supplying the entire amount of the sodium hydroxide aqueous solution, evacuation is started, and while stirring, air is introduced into the container body from the air inlet 8 and the stirring speed is reduced to 220 rpm. The body temperature was maintained at a constant temperature of 80 ° C., the water in the main body was evaporated, and dry particles were obtained in about 30 minutes.
The obtained dried particles were put into water and stirred to dissolve impurities such as alkalis adhering thereto, and then the particles were settled and the supernatant liquid was decanted. Next, the settled particles are dehydrated using a press to recover a cake containing about 10% of moisture, and the cake is dried using a hot air dryer until the moisture content is 1% or less. Next, nickel hydroxide particles coated with cobalt hydroxide hydroxide were obtained.
The various characteristics of the obtained particles are shown in Table 2 together with the characteristics of the raw material particles and the characteristics of the particles produced using a conventional batch fluid drying apparatus.
[0032]
[Table 2]

[0033]
As shown in Table 2, the cathode material particles obtained using the apparatus and method of the present invention have particle characteristics comparable to those obtained by the conventional method, in particular, the TAP density. Further, the steam consumption per product required for the reaction was about ½ of the conventional method in which particles are fluidized by heated air.
[0034]
【The invention's effect】
The present invention depends on the stirring force for the flow of particles in the main body of the apparatus and does not require a large amount of air heating, so that the energy consumption is small, and it is not necessary to use auxiliary heating by microwaves, thereby reducing the production cost of the positive electrode material. .
The present invention provides an inexpensive method for producing a positive electrode 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 inlet 6: Spray nozzle 7: Exhaust port 8: Air inlet 9: Chopper

Claims (6)

(A) introducing water vapor into a jacket of a jacketed vertical high-speed mixing granulator provided with an air inlet and an exhaust port on the upper lid, and heating the inside of the main body to 50 to 130 ° C;
(B) While continuing the introduction of water vapor into the jacket, the α-cobalt hydroxide-deposited nickel hydroxide particles were introduced into the main body and stirring was started. Heating to ~ 120 ° C,
(C) While spraying the alkali metal hydroxide aqueous solution from the spray nozzle onto the α-cobalt hydroxide-deposited nickel hydroxide particles, the step of continuously stirring and spheroidizing the particles; and (d) starting the exhaust. A step of continuously stirring and introducing water vapor into the jacket while introducing air into the apparatus, and subjecting α-cobalt hydroxide to higher-order oxidation to γ-cobalt oxyhydroxide and drying the particles. A method for producing a positive electrode material for an alkaline secondary battery, wherein no auxiliary heating is used.   2. The raw material α-cobalt hydroxide-coated nickel hydroxide particles are particles obtained by depositing α-cobalt hydroxide on the surface of nickel hydroxide particles obtained by wet neutralization. the method of.   The method according to claim 1, wherein the alkali metal hydroxide aqueous solution sprayed in step (c) is a 32-48% sodium hydroxide aqueous solution.   The method according to claim 1, wherein the TAP density of the obtained positive electrode material for an alkaline secondary battery is 2.2 to 2.4 g / cc. The method according to claim 1, wherein the obtained BULK density of the positive electrode material for an alkaline secondary battery is 1.6 to 1.8 g / cc. The method according to claim 1, wherein the average particle diameter of the obtained positive electrode material for an alkaline secondary battery is 9 to 13 μm.

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