JP2002003223A - Surface electroconductive oxy nickel hydroxide and method for manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface electroconductive oxy nickel hydroxide and a method for manufacturing it. SOLUTION: The surface electoconductive oxy nickel hydroxide concerned to this invention has a characteristic that it is produced by two processes consisted with the first process in which particles of nickel oxide and cobalt salt are reacted in the solution of pH 5-11 to get intermediate product and the second process in which the aforesaid intermediate product is oxidized in the solution and it has superior electro conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface conductive nickel oxyhydroxide and a method for producing the same.

[0002]

2. Description of the Related Art Surface-conductive nickel oxyhydroxide is obtained by oxidizing nickel hydroxide in an aqueous solution to form nickel oxyhydroxide, and reacting the obtained nickel oxyhydroxide with a cobalt salt in an aqueous solution. (Step B) of obtaining a nickel oxyhydroxide coated with a cobalt compound by heating and a step C of subjecting this to a long-time heat treatment with an aqueous sodium hydroxide solution (Japanese Patent Application No. 10-214622). ). In addition, the surface conductivity of the resulting surface-conductive nickel oxyhydroxide is not always sufficient, and it has been desired to provide a surface-conductive nickel oxyhydroxide having excellent surface conductivity.

[0003]

Means for Solving the Problems The inventor of the present invention has a pH of 5-1.
The present inventors have found that a surface conductive nickel oxyhydroxide obtained by further oxidizing an intermediate obtained by reacting granular nickel hydroxide and a cobalt salt in an aqueous solution in aqueous solution is excellent in surface conductivity. Was completed. That is, the present invention provides a surface comprising a step 1 of reacting granular nickel hydroxide and a cobalt salt in an aqueous solution having a pH of 5 to 11 to obtain an intermediate, and a step 2 of oxidizing the obtained intermediate in an aqueous solution. An object of the present invention is to provide a method for producing conductive nickel oxyhydroxide.

Further, the present invention is characterized in that, in the step 1, the pH is in the range of 9 to 11, and an ammonium salt is dissolved in the aqueous solution. A method for producing nickel is provided. Further, the present invention provides a surface conductive nickel oxyhydroxide having excellent surface conductivity.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of a surface-conductive nickel oxyhydroxide according to the present invention comprises a step 1 of reacting granular nickel hydroxide with a cobalt salt in an aqueous solution having a pH of 5 to 11 to obtain an intermediate. And oxidizing the obtained intermediate in an aqueous solution. The properties, shapes, etc. of the obtained intermediate and surface conductive nickel oxyhydroxide depend on the shape of the reaction vessel, the stirring method, the concentration of the reactants in the reaction solution, the reaction time, etc. It is easier for those skilled in the art to appropriately select and optimize

(Step 1) The pH value in step 1 may be 5 or more. The pH range is more preferably pH
5 to 11. The pH value of the reaction solution can be kept constant, for example, by adding an alkali metal hydroxide as needed. The alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide. Further, the step 1
An ammonium salt can also be added to the reaction solution in the above. The ammonium salt is, for example, ammonium sulfate or ammonium chloride. The reaction temperature is 20-60
C. is preferred. More preferably, the lower limit is 30 ° C,
The upper limit is 50 ° C. More preferably, the lower limit is 35
° C, the upper limit is 45 ° C.

The granular nickel hydroxide used as a raw material in the step 1 preferably has an average particle size of 6 to 15 μm. Further, eutectic containing other metals can also be used as nickel hydroxide. Other metals include Zn and Co. When the water content is 0.6%, Zn is added in an amount of 0.1 to 6.0 wt.
%, And eutectic nickel hydroxide containing 0.1 to 5.0 wt% of Co can be used. The cobalt salt that can be used in step 1 may be a cobalt salt that becomes divalent cobalt ion in an aqueous solution. For example, cobalt sulfate, cobalt nitrate, and cobalt chloride can be mentioned.

The intermediate obtained in step 1 is nickel hydroxide whose surface is coated with cobalt hydroxide. Specifically, the cobalt hydroxide is considered to be α-form, β-form or a mixture thereof. The cobalt hydroxide is preferably α
Type cobalt hydroxide. If necessary, the obtained intermediate can be washed with water and used as a raw material in step 2. Further, if necessary, the obtained intermediate can be separated and used as a raw material in step 2. For example, filtration can be mentioned as a separation method. If necessary, the obtained intermediate can be dried and used as a raw material in step 2. For example, drying methods include hot air drying and vacuum drying.

(Step 2) In step 2, water and the intermediate obtained in step 1 are added to a reactor and stirred. Further, an oxidizing agent dissolved in water is added, and the mixture is heated and reacted for several hours to obtain surface conductive nickel oxyhydroxide. The oxidizing agent that can be used in the step 2 may be any one that oxidizes the intermediate cobalt hydroxide and nickel hydroxide obtained in the step 1. For example, sodium hypochlorite, potassium hypochlorite, sodium persulfate, and potassium persulfate. Oxidizing agents that can be used are preferably sodium hypochlorite and potassium hypochlorite. The reaction temperature is preferably in the range of 20 to 70C. More preferably, the lower limit is 30 ° C and the upper limit is 60 ° C. More preferably, the lower limit is 35 ° C and the upper limit is 55 ° C. If necessary, the obtained surface conductive nickel oxyhydroxide can be washed with water. Further, if necessary, the obtained surface conductive nickel oxyhydroxide can be dried. For example, drying methods include hot air drying and vacuum drying.

Surface-conductive nickel oxyhydroxide The surface-conductive nickel oxyhydroxide obtained by the production method of the present invention is nickel oxyhydroxide whose surface is coated with a cobalt compound and has excellent surface conductivity. . As a result of observing the surface of the nickel oxyhydroxide coated with the cobalt compound with an electron microscope, it was confirmed that the surface of the nickel oxyhydroxide was uniformly coated with the cobalt compound as shown in FIGS. 1 and 2. You can check.

[0011]

Example 1 10 L of water was put into a 15 L cylindrical reaction vessel equipped with a stirrer, and the mixture was stirred at a constant speed while maintaining the temperature at 40 ° C. Nickel hydroxide (dry granules with water content of 0.6%, Z
1.2 kg of a eutectic containing 4.0 wt% of n and 1.5 wt% of Co and having a mean particle diameter of 10.5 μm) were added to the reaction vessel. While maintaining the stirring speed at which the added nickel hydroxide is uniformly dispersed, 1 part of an aqueous solution of cobalt sulfate (containing 84 g / L of Co) is added.
It was continuously added to the reactor at a rate of 0 ml / min for 100 minutes. During the reaction, a 30 wt% aqueous sodium hydroxide solution was added intermittently so that the pH of the reaction solution was always maintained at 8.0.
The granular material in the reaction tank was washed with water, filtered, and dried at 60 ° C. for 15 hours. As a result, a green dry granular intermediate in which the surface of nickel hydroxide was coated with cobalt hydroxide was obtained.

Next, 6 L of water was put into a 15 L cylindrical reaction vessel equipped with a stirrer, and 1.2 kg of the intermediate obtained above was added thereto, followed by stirring at a constant speed. 4 L of an aqueous solution of sodium hypochlorite (available chlorine amount: 14%) was added thereto, and the reaction was performed for 2 hours while maintaining the reaction temperature at 50 ° C. After completion of the reaction, the particulate matter in the reaction tank was washed with water, filtered,
Dried for hours. As a result, nickel oxyhydroxide (black granular material) coated with the cobalt compound was obtained. A pressure of 10 N / cm ² was applied to the obtained black granular material to produce a plate-like solid having a thickness of 2 mm. When the resistance was measured in the thickness direction of the solid, it was 0.93Ω. The average particle size of the obtained black granular material (using LA-910 manufactured by HORIBA, Ltd. and following the operating procedure) was 10.6 μm. Further, X-ray diffraction analysis of the black granules (using the black granules as they are, RINT200 manufactured by Rigaku Corporation)
Using 0 (Cu-Kα), the operating procedure was followed. ) Was consistent with the peak of β-type nickel oxyhydroxide (JCPDS card number = 60141).

Example 2 10 L of water was put into a 15 L cylindrical reaction tank equipped with a stirrer, and 400 g of ammonium sulfate was added to dissolve it.
Here, a 30 wt% aqueous sodium hydroxide solution was added so that the pH became 10.5, and the temperature was maintained at 40 ° C., and stirring was performed at a constant speed. Subsequent operations are based on the p of the reaction solution.
The same operation and measurement as in Example 1 were carried out, except that H was kept at 10.5 at all times. As a result, black dried granules of nickel oxyhydroxide coated with a cobalt compound having conductivity were obtained. The resistance was 0.90Ω and the average particle size was 10.5 μm. In addition, the peak coincided with the peak of β-type nickel oxyhydroxide (JCPD
S card number = 60141).

[0014]

According to the process for producing surface-conductive nickel oxyhydroxide of the present invention, a step 1 of reacting granular nickel hydroxide with a cobalt salt in an aqueous solution having a pH of 5 to 11 to obtain an intermediate.
And a step 2 of oxidizing the obtained intermediate in an aqueous solution. The surface-conductive nickel oxyhydroxide obtained by the production method according to the present invention is nickel oxyhydroxide whose surface is coated with a cobalt compound, and has excellent surface conductivity. In addition, it exhibits excellent performance as a positive electrode material for Ni-Mn.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of a surface conductive nickel oxyhydroxide obtained by the production method of the present invention.

FIG. 2 is an electron micrograph showing an enlarged surface of surface conductive nickel oxyhydroxide obtained by the production method of the present invention.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tokushi Iida 5-10, Sakahama-wari, 45, Shirakata-cho, Fukui-shi, Fukui F-term in Tanaka Chemical Laboratory Co., Ltd. 4G048 AA04 AB02 AC04 AC06 AE05 AE07 5H050 AA01 BA11 CA03 DA02 DA10 EA01 EA12 FA17 FA18 GA15 GA22 HA10

Claims (3)

[Claims] 1. A step 1 of reacting granular nickel hydroxide with a cobalt salt in an aqueous solution having a pH of 5 to 11 to obtain an intermediate.
And a step 2 of oxidizing the obtained intermediate in an aqueous solution. 2. In the step 1, the pH is 9 to 1.
2. The method for producing a surface conductive nickel oxyhydroxide according to claim 1, wherein the ammonium salt is dissolved in the aqueous solution. 3. A surface conductive nickel oxyhydroxide obtained by the production method according to claim 1.