JP3426649B2 - Method for producing nickel active material for alkaline storage battery - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is, Knitting for an alkaline storage battery
The present invention relates to a method for producing a keel active material . 2. Description of the Related Art Conventionally, in order to increase the activity (charging efficiency) of a nickel active material, a nickel hydroxide crystal has to be strained.
Cause, that is the disruptive of crystals are known to be effective. And as a method for this,
A method for forming a solid solution of nickel and zinc has been proposed (JP-A-2-30061). In this method, an alkali acts on a mixed crystal salt of nickel and zinc, and nickel and zinc are coprecipitated to form a solid solution. According to this method, distortion of the nickel hydroxide crystal is caused by the presence of zinc , and the order of the crystal is disturbed, so that the activity of the active material is increased. [0004] However, the above method has the following problems. That is, since zinc has a higher solubility and a lower deposition rate than nickel, a part of zinc in the mixed crystal salt is eluted into the alkaline solution and then taken in the active material again to precipitate. For this reason, crystals of zinc alone that do not form a solid solution are also formed, resulting in an inert layer or insufficient formation of a solid solution of zinc-nickel .
You . Therefore, the activity of the active material could not be sufficiently increased. The present invention has been made in order to solve the above-mentioned problems, and has established a method for further promoting the solid solution of nickel and zinc, and has established an alkali having an excellent activity.
An object of the present invention is to provide a method for producing a nickel active material for a rechargeable battery . [0006] [0007] [Means for Solving the Problems] In order to achieve the above purpose
The present invention according to claim 1 is a nickel active material for an alkaline storage battery.
The method for producing zinc, wherein zinc is contained in an amount of 3 to 9 mol%.
An alkaline aqueous solution obtained by adding zinc to a nickel salt having
It is characterized by producing an active material of nickel electrode by acting
And [0008] [0009] [action] d for an alkaline storage battery according to claim 1 of the structure
In the method for producing a nickel active material, zinc is added in an amount of 3 mol% to 9 m.
ol% containing nickel salt with zinc added in advance.
Since the active material is generated by the action of the potassium solution,
When co-precipitating Kel and zinc to form a solid solution, zinc
Is higher than nickel and has a slower deposition rate.
Insufficient solid solution of zinc-nickel
Can be suppressed. Therefore, when forming a mixed crystal salt of nickel and zinc, the deposition rate of nickel and zinc can be made close to each other, and the solid solution can be favorably advanced. [Example] [0010] Zinc oxide is dissolved in an aqueous sodium hydroxide solution until saturation is reached to prepare a zinc-saturated alkaline aqueous solution, while zinc nitrate is dissolved in 0, 3, 6, 9 mol%. To prepare a nickel nitrate solution. Then, a porosity of 85% was obtained by a chemical impregnation method.
Was filled with a nickel active material. To explain the characteristic matter in this filling, first, the nickel nitrate solution was impregnated into the nickel substrate .
Thereafter, the substrate is immersed in the aqueous solution of zinc-alkali to form a nickel-zinc solid solution in the pores.
Kell active material was charged. Operations other than those described above were performed according to a conventional method. In this way, zinc is added to each of 0, 3,
A nickel electrode (positive electrode) filled with a nickel hydroxide active material containing 6.9 mol% was prepared. In addition, the zinc content produced as described above is 0 mol% and 9 mol%.
% Nickel hydroxide electrode will be treated as the electrode of the present invention below for convenience of explanation. Comparative Example A nickel hydroxide electrode was produced in the same manner as in the above example, except that an aqueous solution of sodium hydroxide containing no zinc compound was used. Experiment 1 above adjusted invention nickel hydroxide active material crystal, and the nickel hydroxide active material crystals of Comparative Example, subjected to X-ray diffraction analysis under the following conditions, determine the spacing of (001) plane Was. Then, the solid solution state was evaluated by comparing the above-mentioned plane spacing of both crystals. (X-ray diffraction conditions of the diffraction analysis) · TARGET / FILTER (MONOCHRO) : CuKα · VOLTAGE / CURRENT: 30kV / 12.5mA · SCAN SPEED: 5 DEG / MIN Incidentally, the solid solution of the crystal proceeds, a uniform crystal structure Since distortion occurs, the position of the X-ray diffraction peak shifts. Therefore, it is possible to know the degree of distortion from the magnitude of the plane spacing and evaluate the solid solution state. Table 1 shows the plane spacing of the (001) plane measured by X-ray diffraction analysis, and FIG. 1 is a graph showing the relationship between the zinc content (mol%) in the active material and the plane spacing (Å). [Table 1] As is clear from Table 1, the zinc content is 0%.
No difference was observed between the product of the present invention and the comparative product. This is because the crystal structure is not disturbed by zinc.
On the other hand, when the zinc content was 3% to 9%, the product of the present invention clearly had a smaller interplanar spacing than the comparative product. FIG. 1 also shows that the interplanar spacing decreases as the zinc content in the active material increases, and that the degree of the decrease is greater in the active material adjusted by the method of the present invention. From these, according to the method of the present invention,
It can be seen that solid solution formation of nickel and zinc can be sufficiently advanced. [Experiment 2] Potassium hydroxide having a specific gravity of 1.23 using the electrode of the present invention and the electrode of the comparative example prepared above and a nickel plate as a counter electrode.
The charge / discharge efficiency of the electrode was examined in an aqueous electrolyte solution . The charge / discharge efficiency is calculated by charging the theoretical capacity in one hour.
The current value that can be charged is 1C, and after charging at 1 / 3C for 120 minutes, the potential of the nickel plate reference is -0.8V at 1 / 3C.
Discharged until, (discharge capacity / charge capacity) × 100
(%). The results are shown in Table 2 and FIG. [Table 2] From Table 2, it was found that when the zinc content was 3% to 9%, the product of the present invention had higher charge / discharge efficiency than the comparative product. From FIG. 2, it was found that the zinc content in the active material (mol
%) As the increase, charge discharge collection efficiency has been found to be elevated. [Experiment 3] With respect to the electrode of the present invention and the electrode of the example produced as described above, the electrode plate utilization was determined. The electrode utilization rate is as follows: after charging at 0.1 C for 24 hours to make the battery fully charged, at 1/3 C the nickel plate is used.
The potential of the reference is discharged to -0.8 V, it was determined by calculating the (discharge capacity <br/> amount / charge capacity) × 100 (%). The results are shown in Table 3, and the relationship between the zinc content in the active material and the electrode plate utilization is shown in FIG. [Table 3] As is clear from Table 3 and FIG. 3, all of the products of the present invention having a zinc content of 3 to 9% had higher electrode plate utilization rates than the comparative products. However, even in the case of the product of the present invention, when the zinc content was 9%, the electrode plate utilization was a very low value of 83.5%. This indicates that the zinc content in the nickel active material is preferably 6% or less. As described above, when the results of Experiments 1 to 3 are combined, it is necessary that at least zinc is contained in the nickel active material (Tables 1 and 2). On the other hand, it is concluded that the zinc content is preferably 6% or less (Table 3). According to the present invention, a nickel hydroxide active material in which solid solution of zinc and nickel has been suitably advanced can be obtained, and the nickel active material has a high activity. It will be. Therefore, the alkaline storage according to the present invention
According to the production method of the pond nickel active material, the activity is excellent
Thus, a nickel active material can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a relationship between a zinc content in a nickel active material and charge / discharge efficiency. FIG. 2 shows the zinc content in the nickel active material and the nickel hydroxide content.
It is a figure which shows the relationship with the (001) plane spacing of a Kell active material . FIG. 3 is a graph showing a relationship between a zinc content in a nickel active material and an electrode plate utilization factor.

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Claims (1)

(57) [Claim 1] Zinc is contained in an amount of 3 mol% to 9 mol%.
An alkaline aqueous solution containing zinc added is acted on the nickel salt.
The active material of the nickel electrode
A method for producing a nickel active material for an alkaline storage battery.