JPS60211767A - Manufacturing method of nickel positive electrode for alkaline storage battery - Google Patents

Abstract

PURPOSE:To improve and stabilize the coefficient of utilization of an active material by containing the alkaline metal including at least lithium in nickel hydroxide powder that forms the principal substance of the active material powder. CONSTITUTION:An aggregate of elementary particles is formed by adding lithium hydroxide powder as alkali while nickel sulfate is being dissolved and agitated in water and leaving them alone for one hour at approximately 50 deg.C for aging. Then powder whose principal component is nickel hydroxide powder is obtained by filtering, drying, pulverizing, adjusting in specified granularity, fully washing with water, and drying this precipitate. This nickel hydroxide powder, carbonyl nickel powder, and carbonyl cobalt powder are mixed and formed into paste by adding water to them. An electrode is obtained by filling the inside of a foamed nickel plate with the paste, drying and pressurizing it.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a nickel positive electrode for alkaline storage batteries, in which nickel hydroxide powder is used as a living material and is directly filled inside a support. It can be applied to general positive electrodes that are coated on support plates.

Structures of conventional examples and their problems The following types of nickel positive electrodes are mainly used: The first method is called a sintering method in which a nickel salt solution is used, filled into a nickel sintered body, and then converted into nickel hydroxide, which is an active material. The second method is to directly fill a support with nickel hydroxide powder.

For the latter, a metal bag with many micropores or a pocket type or foamed metal type, in which the inside of a foamed metal body is filled with nickel hydroxide powder as the main constituent, are usually adopted or proposed industrially. has been done. In addition, a pressurizing method has also been proposed, typified by a method in which the coating is applied to a sheet metal such as punched metal or expanded metal and pressurized into one piece.

Nickel positive electrodes based on these methods have in common that nickel hydroxide powder is used directly as an electrode material as an active material powder. The manufacturing method is relatively simple compared to a sintered nickel positive electrode, and electrodes using a foamed metal type or a pressurized type have the possibility of increasing the packing density of the active material.

This is because the volume ratio of the support material, such as foamed metal or punched metal, in the electrode can be reduced compared to a sintered substrate. However, the current situation is that the utilization rate of active materials is generally lower than that of sintered nickel positive electrodes. Among them, the foamed metal type has a relatively small difference in active material utilization rate, but its stability is currently inferior, with an average of 5.
~1o% (the theoretical amount of trivalent nickel hydroxide → divalent reaction is 1%)
00%) is observed.

In general, the sintered type is superior to these three types in terms of various electrode properties (charge/discharge rate and physical strength), but in terms of energy density, the former can achieve higher UjlJ at a normal discharge rate. However, in order to make full use of its advantages in practical terms (energy density reduction or discharge capacity density), it is necessary to further improve the active material utilization rate (currently 76 to 9
0%).

The nickel hydroxide powder used in these methods is usually hydrated in a nickel salt (sulfate, nitrate, etc.) solution).
A method is adopted in which nickel hydroxide is precipitated by adding Jium powder or an alkali solution thereof. When the powder thus obtained is used alone as it is as a filler for electrodes, the active material utilization rate is 60 to 60%. Therefore, in order to improve the utilization rate, there is a proposal to increase the utilization rate to 75-90% by adding cobalt, nickel, or carbon. However, the general-purpose sintered nickel positive electrode (9
At present, the value of 111 is still low compared to 0% to 1o0%, and the variation is large. In addition, the effects of adding lithium (improvement of active material utilization rate and charge acceptance) are already known, and in sintered nickel positive electrodes, lithium is added in the active material filling → conversion step, followed by the chemical formation process in alkali. A proposal has been made to add However, in the case of electrodes that are directly filled with active material powder, unlike the sintered type, there is no need to remove anions such as nitrate radicals, and chemical formation can be omitted, and the process of chemical formation → water washing → drying can be omitted. is preferred. Furthermore, when lithium was added through chemical formation, it was only added to the surface of lithium hydroxide, and no significant effect was observed in terms of the utilization rate of the active material.

Purpose of the Invention The purpose of the present invention is to improve and stabilize the utilization rate of active materials by improving nickel hydroxide powder, which is a powder of living substances.

Structure of the Invention In order to achieve the above-mentioned object, the present invention prepares a nickel hydroxide powder, which is the main component of an active material powder, which has an alkali metal containing at least lithium inside it, and coats it on a support plate. The active material powder 1 mainly consists of nickel hydroxide powder.
A schematic cross-sectional view of a nickel electrode in which a space 3 of a foamed nickel porous body 2 serving as a support is filled with is shown. The Σnickel hydroxide powder used here contains 0.005 wt
It is a powder containing 4 or more lithium. Lithium is 0
．． 0.005 to 0.02 wt%, resulting in an improvement in the utilization rate.
Even if it contains 0.02 wt% or more, the utilization rate of the active material will be saturated, and the content will vary depending on conditions such as precipitation of nickel hydroxide and aging and washing described below, so we purposely did not set an upper limit.0 Nickel hydroxide powder The manufacturing method is the main steps shown in Figure 2: A: Dissolution of nickel sulfate → B: Addition of an alkali such as NaOH to precipitate and age nickel hydroxide → G: Filtration →
In the process of D drying → E crushing → F water washing → G drying → H nickel hydroxide powder, at least LiOH is added when nickel hydroxide is precipitated by addition of alkali in B, and nickel hydroxide is left to age during this process. When forming aggregate particles, Ll is included inside.

The pocket type, foam metal type, and pressurized type nickel positive electrodes used as this nickel hydroxide powder powder are manufactured using almost similar manufacturing methods, so we will take the foam metal type nickel positive electrode as an example and explain the specific details. Give an explanation.

Description of Examples (Example 1) 13 volumes of crystalline nickel sulfate in the form of hexahydrate are dissolved in water to a total volume of 40 ml. While stirring this at about 26° C., 6.5 kLi of lithium hydroxide powder is added as an alkali, and then left to ripen at about 60° C. for 1 hour to form an aggregate of elementary particles. Next, this precipitate is filtered, dried and pulverized to adjust the desired particle size, thoroughly washed with water, and dried to obtain a powder containing nickel hydroxide powder as the main component.
Get a mansion.

This nickel hydroxide powder with a particle size of 0.1 to 150 μm, carbonyl nickel powder, carbonyl cobalt powder
A foamed nickel plate (porosity 95%, average pore diameter 200 μm) was prepared by mixing wt%: 10wt: 5wt and adding water to make a paste.

It is filled to a thickness of 1.3mm), dried and then pressurized to a thickness of about 0mm.
Obtaining 7 electrodes (Example 2) In the step of adding lithium hydroxide to the nickel sulfate solution in Example 1, immediately after adding 1.5 kg of lithium hydroxide, 4 kg of sodium hydroxide or potassium hydroxide was added. 5.6 kg was added, and the subsequent steps were carried out in the same manner as in Example 1 to obtain a foam metal type nickel positive electrode.

(Example 3) When preparing the nickel sulfate solution in Example 1 or Example 2, nickel hydroxide was prepared in the same manner as in Example 1 or Example 2 by adding ○, skg of cobalt metal powder and 1 kg of nickel powder at the same time. A kneaded mixture of powder, cobalt and nickel is obtained. This kneaded product was filled into the same foamed nickel as in Example 1.

Obtain a foamed metal nickel positive electrode.

Nickel positive electrode obtained in Example 1 (Li in Ni(OH)2
The -R-AA size of the sealed cylindrical nickel-cadmium storage battery was taken up as a means of investigating the active material utilization rate (using powder with an amount of 0.03 wt%). Approximately 0.7n++++, the same thickness as a general-purpose sintered nickel positive electrode
), but by reducing the area by about 10% and increasing the negative electrode capacity by an equivalent volume, a battery was constructed that satisfied the theoretical sealed configuration conditions. Discharge capacity when this battery is charged at 50 mA for 15 hours and discharged at 100 mA (final voltage 1.
Check OVl and fill N1(OH)2 (gravimetric measurement)
Figure 3 shows the results of calculating the utilization rate as 289 mAh/q.

In FIG. 3, the highest and lowest discharge capacities of the 10 batteries that exploded are removed, and the range of the highest and lowest utilization rates of the remaining eight batteries is shown. Note that charging and discharging were performed at 20'C.

At the same time, for comparison, the electrode I N'1 (OH
) 2) and electrodes obtained by reducing the amount of LiOH added in Example 2 (Li amounts of approximately 0.01 wt% and 0.005 wt%) and as conventional (7) N30H The amount of Na in Nl(OH)2 is approximately 0.0
The horizontal axis shows the results of a battery using a foamed metal nickel positive electrode obtained in the same manner as in Example 1 using 3wt%).
The amount of i (wt%) is shown as a variable. Both are battery 1Q
These are the results of the remaining 8 samples after testing 8 samples and removing the maximum and minimum values of discharge capacity.

As a result, an electrode directly filled with the nickel hydroxide powder containing lithium according to the present invention has a higher active material utilization rate than a conventional powder that does not contain lithium, and can be used for general purpose. It was found to be equivalent to a sintered nickel positive electrode. The effect was seen from LJ, 006 wt%, and as the amount increased, the utilization rate improved at 0503 wt%4, and at the same time, there was a tendency for the variation to decrease.

Effects of the Invention As is clear from the above description, the nickel positive electrode of the present invention can be manufactured by directly filling the support with nickel hydroxide powder containing alkali metals including lithium or by coating it on the support plate. It is possible to provide an electrode that is relatively easy to manufacture and has a high capacity density.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the nickel electrode according to the present invention, Figure 2 is a schematic diagram of the manufacturing process of nickel hydroxide, and Figure 3 is the use of active material in batteries using the nickel hydroxide powder containing lithium according to the present invention. It is a figure which shows the result of actually measuring a ratio. 1... Active material powder mainly composed of nickel hydroxide, 2... Foamed nickel porous body, 3...
Space department. Figure 1 Ntontono Mashiri Kataro Hina 1% Ji

Claims (1)

[Scope of Claims] (1) A method for producing a nickel positive electrode in which an active material powder mainly composed of nickel hydroxide powder is applied to a support plate or filled inside the support, the method comprising: 1. A method for producing a nickel positive electrode for an alkaline storage battery, comprising using an alkali metal containing at least lithium inside the nickel positive electrode. (2) The amount of lithium contained in the nickel hydroxide powder is 0
．． The method for producing a nickel positive electrode for an alkaline storage battery according to claim 1, wherein the content is 0.005 wt% or more. (3) The method for producing a nickel positive electrode for an alkaline storage battery according to claim 1, wherein the nickel hydroxide powder is precipitated by adding an alkali containing at least lithium to a nickel salt solution. (4) Claim 3, characterized in that when nickel hydroxide powder is precipitated from a nickel salt solution containing lithium and an alkali added, cobalt metal alone or cobalt salt is added to the nickel salt solution simultaneously with the alkali.
A method for producing a nickel positive electrode for an alkaline storage battery as described in . (6) When precipitating nickel hydroxide powder from a nickel salt solution to which an alkali containing lithium is added, a conductive powder is added to the nickel salt solution at the same time as the alkali. The method for producing a nickel positive electrode for alkaline storage batteries according to item 4.