JPH0773049B2 - Method for manufacturing battery electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing an electrode for a battery, which is used in an alkaline storage battery or the like, and which uses a porous metal body having three-dimensional communication holes as a substrate. is there.

(B) Conventional technology As a method for manufacturing electrodes used in sealed alkaline storage batteries, etc., in recent years, instead of the sintering method, it is made by filling a metal porous body having three-dimensional communication holes with active material powder. Non-sintered manufacturing methods have been studied. This manufacturing method is regarded as an effective manufacturing method for cost reduction and performance improvement because the manufacturing process can be simplified, the manufacturing time can be shortened, and the energy density of the electrode can be easily increased.

Specifically, this typical manufacturing method is based on the following steps. A felt-like sintered body of nickel fiber (hereinafter referred to as nickel matrix, having a fiber diameter of 20μ, an average pore diameter of 50μ and a physical property of porosity of 93%) is used as a substrate, and a nickel hydroxide powder having an average particle diameter of 20μ is mainly used as the base. Fill the slurry prepared by mixing the active material powder and the paste liquid to
After drying, it is compressed under pressure to obtain a finished electrode.

The major difference between this manufacturing method and the conventional sintering type manufacturing method is that the former separately manufactures the active material slurry and fills it into the inside of the substrate, while the latter impregnates the active material raw material salt solution inside the substrate and then chemically , Electrochemical, or thermal methods,
This is to convert this raw material salt into an active material. The latter is
Since the difference between the active material density and the salt solution density is large, it is not possible to perform a predetermined amount of filling in one filling operation, and therefore it is necessary to repeat the filling operation for several times. The former compensates for the low packing density and therefore requires pressing in a later step, but has the advantage that the packing can be completed in a single operation. By the way, this characteristic is that the sinter-type manufacturing method can measure the filling amount one after another and accurately adjust it to a predetermined value. There is a problem that it is difficult. Various methods for filling an active material into a three-dimensional porous metal have been proposed (see, for example, JP-A-53-53).
No. 10333) Nothing suggests the above problems.

(C) Problems to be solved by the present invention The present invention has been made in view of the above problems, with respect to the metal porous body, the main object is to accurately match the filling amount of the active material slurry with the set amount, The quality of the battery electrode obtained by such a manufacturing method is stable and the electrode characteristics are improved.

(D) Means for Solving the Problems The method for producing a battery electrode of the present invention is a metal porous body having three-dimensional continuous pores, filled with an active material slurry, and then partially contained in the active material slurry. It is characterized in that the metal porous body is compressed to a predetermined thickness by a roller installed so as to be submerged and further a blade is applied.

(E) Action The inventors of the present invention set the powder and the dispersion medium (slurry constituent) on the substrate as a condition for uniformly filling the porous metal body (substrate) having three-dimensional continuous pores. (For example, paste)
It has been found that, when it is necessary to fill the substrate with the slurry-like active material, the set value of the filling amount is based on the slurry density, the porosity of the substrate, and the thickness. That is, the required amount of slurry (volume) can be determined from the slurry composition for the set amount of active material, and the required thickness of the substrate can be determined from this, the dimensions (vertical / horizontal) of the substrate, and the porosity. Therefore, theoretically, if the weight per unit area of the substrate, the thickness, and the slurry composition are uniform, a uniform filling amount that matches the set value can be obtained. However, in reality, the thickness and weight of the substrate fluctuate within a certain range, and bubbles may be mixed in the filled slurry, so that it is difficult to make the filling amount uniform. For this reason, there is also a method of making the substrate thickness constant by passing it through a roller before filling, but the sufficient effect cannot be obtained.

On the other hand, the inventor tried adjusting the thickness after filling, and realized that the effect was great, and completed the present invention. This method makes the substrate a little thicker than a predetermined thickness,
This is filled with the active material slurry, and then the base is compressed to a predetermined thickness through a roller, the surplus active material slurry is discharged, and the slurry adhering to the surface of the base is scraped off with a blade and then dried. Is.

It is speculated that the reason why the effect of filling the slurry once excessively and then passing it through the roller is so great is that the air mixed during filling is discharged when the roller compresses and the variation in the filling rate is reduced. .

The test results relating to the above contents are shown below.

The active material slurry has nickel hydroxide as a main component, sodium hexametaphosphate 0.1 wt%, hydroxypropyl cellulose (HPC) 0.1 wt%, and water 30 wt% are added to prepare a viscosity of 3000 CP. The substrate has an average pore diameter of 250 μ, Thickness 1.0 mm
In the sponge-like nickel (metal porous body) filling method, a filling roll is installed inside, and the hoop-like substrate is introduced into a filling tank filled with the active material slurry. Table 1 shows the results of comparing the filling rates by adjusting the thickness of the substrate before or after the slurry filling.

From Table 1, it can be seen that the dispersions adjusted after filling have a small variation (σ) and a high filling rate. On the other hand, in the experiment, the thickness adjusting roller squeezes the once filled slurry from the substrate, but when continuously operating,
It has been found that the solid content of the squeezed slurry may stick to the roller surface in some cases and it is necessary to prevent this, and that the variation in the filling amount varies depending on the roller position. An experiment was conducted on this, and the roller position is that at least part of the roller is in contact with the slurry liquid level,
It has been found that it is desirable that the roller is pressed to the substrate pressing portion in the slurry (see Table 2), and that the compression amount should not exceed 0.1 mm (see Table 3).

The results of this experiment are shown in Table 2 and Table 3 below. The slurry composition and the substrate are the same as those described above. In Table 2, ⊚ indicates that there is no deposit on the roller surface, and ○
Indicates that the roller can be continuously operated although there is a slight amount of deposit, and Δ indicates that the roller can be operated only for a short time. In Table 3, the roller position is in a state of being half immersed in the slurry.

The reason why the roller is better in the slurry is that the wet state of the roller surface becomes constant, and the solid content ratio (slurry water content) of the slurry squeezed from the substrate is the same as that of the slurry in the tank. This is because solid-liquid separation does not occur. When the roller is completely submerged in the slurry, the filling amount increases a little because the base is spring-backed after the thickness is adjusted by the roller, and if there is a large amount of slurry around the base, it is This is because they are filled. Therefore, it is preferable that at least a part of the roller position is in contact with the slurry in the tank, and if possible, the roller position is set so as to be submerged up to a half of the existing substrate.

Further, with respect to the thickness adjustment range, it is necessary to avoid the compression of more than 0.10 mm because the accuracy of the substrate thickness decreases and the powder adheres to the roller surface. Compression amount 1.0 mm
The reason why the filling rate is improved as described above (see Table 3) is that water is preferentially squeezed out from the filled slurry to lower the water content.

Even if filling is performed under such conditions, a thin film of slurry is formed on the surface of the substrate, but the film thickness is not uniform. Therefore, the variation in the filling amount can be further reduced by applying a blade before the final stage drying and removing this film.

(F) Example A typical configuration of an apparatus for carrying out the present invention is shown in the figure as a schematic diagram. In the figure, 1 is a filling tank, 2 is an active material slurry, 3 is a substrate, 4 and 6 are guide rollers, 5 is a filling roller, 7 is a blade, and 8 is an active material for adjusting the substrate thickness, which is a feature of the present invention. It is a thickness control roller installed so that it is submerged in the slurry by half.

(Example 1) 100 parts of powder containing nickel hydroxide as a main component, 0.1 part of HPC,
A slurry having a viscosity of 4000 CP consisting of 0.1 part of sodium hexametaphosphate and 30 parts of water was filled in a sponge nickel having a thickness of 1.0 mm by the device shown in the figure. The compression amount after filling at this time is 0.03 mm.

Example 2 100 parts of powder containing nickel hydroxide as a main component, 0.4 part of HPC,
A slurry of 55 parts of water having a viscosity of 2000 CP was filled in a sponge nickel having a thickness of 1.35 mm under the same conditions as in Example 1.

(Comparative Example 1) The same substrate as used in Example 1 was previously compressed to 0.97 mm and then charged under the same conditions as in Example 1 except that the compression step after filling was omitted.

(Comparative Example 2) The same substrate as in Example 1 was used, and the filling was performed under the same conditions as in Example except that the compression step after filling was omitted. These plates,
After filling all the active material slurry, apply a blade under the same conditions,
It was dried and then rolled with a calendar roller.

Table 4 shows the filling factor of the electrode plates of the above-mentioned examples and the elongation of the electrode plates after rolling with a calender roller.

As described above, the electrode plate according to the present invention has a feature that not only the variation in the filling amount is small, but also the variation in quality in the next step is suppressed.

Further, as shown in Example 2, the effect of the present invention can be similarly obtained as long as the slurry has fluidity and solid-liquid separation hardly occurs, and can be widely applied.

Furthermore, in the examples, only the nickel anode using nickel hydroxide as an active material is described, but the present invention is not limited to this as long as it is a method of directly filling the powdered active material slurried in the three-dimensional metal porous body. It can be applied. Needless to say, a nickel matte or the like can be used as the three-dimensional metal porous body other than the sponge-like nickel shown in the examples.

(G) Effect of the Invention According to the method for producing a battery electrode of the present invention, the active material can be uniformly and accurately filled in the metal porous body, so that the electrode characteristics of the electrode using the metal porous body can be stabilized. Is possible and its industrial value is extremely high.

[Brief description of drawings]

The figure is a conceptual diagram of a filling method schematically showing the present invention. 1 ... Filling tank, 2 ... Active material slurry, 3 ... Substrate (porous metal body), 4,6 ... Guide roller, 5 ... Filling roller, 7 ... Blade, 8 ... Thickness adjusting roller.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masahito Tomita, 2-18 Keihan Hon-dori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Takeio Hamamatsu 2--18, Keihan Hon-dori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A metal porous body having three-dimensional continuous pores is filled with an active material slurry, and then the roller is installed so as to be partially submerged in the active material slurry, so that the metal porous body has a predetermined thickness. A method for producing a battery electrode, comprising compressing and further applying a blade. 2. The method for producing a battery electrode according to claim 1, wherein the slurry active material has a fluidity that does not cause solid-liquid separation. 3. The battery according to claim 1, wherein the roller for compressing the porous metal body is installed so that the compression portion of the porous metal body is immersed in the active material slurry. For manufacturing electrodes for use.