JPS6199269A - Manufacture of positive electrode for alkaline storage battery - Google Patents

Abstract

PURPOSE:To effectually prevent the corrosion of porous nickel base plate by immersing the base plate in a wet oxidizer prior to imprenating the base plate with a nickel salt. CONSTITUTION:First, a porous nickel base plate is sufficiently washed with water and then immersed in a 31% H2O2 solution at ordinary temperature for one minute. Then, the base plate is washed with water to remove the residual H2O2 before the washed plate is dried. The thus treated base plate is then immersed in a nickel salt solution to impregnate the base plate with the nickel salt. Next, the impregnated base plate is dried and then immersed in an alkali bath to convert the nickel salt into nickel hydroxide. After that, the base plate is washed with water to clean it and then the cleaned base plate is dried. The above operations are repeated several times. Accordingly, it is possible to form a homogeneous oxidized film over the base plate.

Description

[Detailed Description of the Invention] A. Field of Industrial Use> This invention relates to a method for producing positive polarity for alkaline storage batteries. This is a method for manufacturing a sintering type water-washed nickel positive electrode used in nickel-cadmium storage batteries, which prevents corrosion of a porous nickel substrate during impregnation. This is about the manufacturing method with the addition of a T-bar.

<Conventional Techniques> Paste type, pocket type, sintered type, etc. are available as types of nickel hydroxide batteries used in alkaline storage batteries such as nickel cadmium storage batteries. Recently, the sintered type has become widely used because the utilization rate of certain nickel hydroxide is higher than that of the narrow type, but the internal resistance is also lower. An outstanding method for producing sintered nickel hydroxide tE t=ff has been put into practical use. For example, first, a slurry-like mixture of sintering metal strength wood such as carbonyl nickel, a binder such as carboxymethyl cellulose, and water is applied to a porous metal material such as a porous nickel thin plate, and then sintered in an inert or hydrogen-reducing atmosphere to form porous nickel 'J+
ff< i′7. Next, this porous nickel substrate is placed in a nila gel salt solution such as a nickel nitrate aqueous solution to impregnate the pores of the substrate with nickel+a, and then immersed in an alkaline bath to mix the nickel salt into nickel hydroxide ( Alternatively, using the same method, a porous nickel substrate is placed in a nickel solution and impregnated with nickel salt, and then electrolytically reduced in a nickel salt solution or alkaline aqueous solution to form a substrate. This method includes filling with nickel oxide.

By the way, the above manufacturing method requires a porous nickel base (
As a result of corrosion of the substrate when impregnating a with nickel salt, a battery was constructed using the obtained positive electrode, and the lζζ association was (]
ₛThe positive electrode swells during repeated overdischarge, and the swelling causes the active material to peel off, resulting in a significant deterioration of the battery discharge capacity, or the corrosion of the substrate causes an increase in the amount of positive electrode active material. It is known that this type of corrosion of porous nickel substrates is caused by hydrogen ions in the nickel salt solution. It is known that this is caused by erosion of the substrate due to nickel attack.

Impregnation treatment 1 as disclosed in Takemonsho No. 58-11264! II! 11 in a methanol solution, or heat oxidize porous raw nickel 'L+Fj in air to form an acid-resistant oxide film on its surface as in Mochima Sho 59J6659@. At present, the above-mentioned inconvenience is addressed by adding

<Problems to be Solved by the Invention> However, the method of impregnating in a methanol solution has the following problems. In other words, the specific gravity of the methanol solution is low, and the impregnation of the nickel salt into the substrate is delayed.
On the other hand, it has been confirmed that if the specific gravity becomes too high, corrosion of the substrate tends to proceed. Therefore, it is necessary to maintain the solution at a predetermined ratio during the impregnation process. However, due to the nature of methanol, although it has a low boiling point, it is highly evaporative, and therefore it is difficult to maintain the specific gravity of the solution constant as described above, making the control of the process f2 complicated and difficult. On the other hand, with methods that oxidize the substrate by heating in the air, it is difficult to form a uniform oxide film (1) because the substrate surface cannot be uniformly oxidized due to the influence of temperature distribution, etc., and reliability is lacking. However, like the above method, there is a problem in that process control is difficult. 7 (Means for resolving problem 1) 7) The manufacturing method for the alkaline storage battery of the present invention is to wet-type the substrate with 01-100 nickel prior to impregnating the porous 11-nickel substrate with nickel salt.
The gist of the method is to include a step of immersing it in a diluting agent. As a wet oxidizing agent, hydrogen peroxide (11ρ2
), potassium permanganate (K\=1nO,), chlorine 1
Disturbances such as potassium monate (K2Or20.)
3 can be used as appropriate, but since there is no need for a post-treatment process to remove impurities generated during oxidation treatment, use oxidized water, 1=:! , : thing is the most) thea Φ.

The oxidizing agent of formula 19, which is described as ``7'', has a stable component in the humidity of the residential environment, 1 odor, 3 ``CJ'', and a uniform coating on the opposite surface (
The surface of the substrate can be uniformly oxidized by scanning the surface of the substrate.

Therefore, a uniform oxide film can be formed with easy process control.
This effectively prevents gambling on the board.

<Example> A porous chive/full substrate was prepared by a known method, and after thoroughly washing the W and TFFI with water, it was immersed in a 31% H2O2 solution at room temperature for 1 minute. The purpose of washing with water as a pretreatment before dipping in H,02 is to remove impurities on the substrate and form a uniform oxide film on the substrate. Immediately after dipping, the substrate was washed with water to wash away the remaining l-1,02, dried, and washed. After that, the substrate is crushed in a nickel salt solution to impregnate the inside of the substrate with nickel salt. After impregnation, the substrate is dried, and after drying, the substrate is immersed in an alkali δ solution to remove the nickel salt from nickel hydroxide. After that, wash the board with water to clean it. A sintered Nilaglu hydroxide front surface was created by repeating the series of operations several times, including washing with water, drying the substrate, and then drying the substrate.

Thus, by combining the single positive electrode with a known negative electrode, an alkaline storage battery with a nominal capacity of 1.2 Ah per day was made, and the charging time was J9.
Changes in the discharge capacity of the battery as the battery was cycled (change when the initial cycle was taken as 100%) were investigated. For comparison, a similar alkaline storage battery was made using sintered nickel hydroxide (1) and sintered nickel hydroxide positive (1) by the same method as above, except that the crushing process of H20E was not performed.
The changes in the discharge chamber were investigated by the same method. These results (charge/discharge cycle characteristics) are shown in the drawing.

In the figure, △ indicates the 1-cycle durability of a battery using a positive electrode that has been immersed in H2. As is clear, for example, at 300 cycles,
The discharge container A, which was immersed in 1□oL, was approximately 93%
In contrast, B without immersion is about 83%, △
is more than 10% better than B. It can also be seen that the battery according to the present invention suffers less capacity deterioration by 1% over the course of charging and discharging cycles, and has a longer lf life due to stable capacity.

7. (Effects of the Invention) The method for producing a positive alkaline storage battery according to the present invention includes the step of immersing a porous nickel plate in a wet oxidizing agent prior to immersion in a nickel salt a. As mentioned above, a uniform oxide film can be formed temporarily with easy process control, and nickel salt impregnation treatment 1. It has the effect of being able to effectively prevent the temporary 195 meals of +1 and improving the cycle's life.

[Brief explanation of drawings]

The drawing is a graph showing charge/discharge cycle characteristics for 1 hour.

Claims (1)

[Claims] 1. A method for producing a positive electrode for an alkaline storage battery, which includes the step of immersing a porous nickel substrate in a wet oxidizing agent prior to impregnation treatment with a nickel salt. 2. The manufacturing method according to claim 1, wherein the wet oxidizing agent uses hydrogen peroxide (H_2O_2).