JPS5887765A - Manufacture of electrode plate for battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an electrode plate for a battery, in which a sponge-like metal porous body having a three-dimensionally continuous network structure is filled with an active material in the form of yeast.

The purpose of this is to apply a paste to the porous body during the manufacturing process of an electrode plate in which a long band-shaped sponge-like porous metal body (hereinafter referred to as the porous body) is continuously filled with an active material in an irst-like manner. It is an object of the present invention to provide a method for manufacturing an electrode plate that is excellent in mass production by providing a step of preliminary pressing using a roller press and subsequent main pressing using a flat plate press after filling and before a drying step. That is, by adjusting the liquid content in the porous body to a ratio A11 suitable for the main press in the preliminary lubrication process, it is possible to make the pressurizing process continuous. In addition, the pressurizing process eliminates the opportunity for the binder to adhere to the pressurizing metal 7311 as a binder additive, thereby reducing maintenance work for pressurizing.

Conventionally, as electrode plates for batteries, methods have been adopted for lead-acid batteries, in which a porous cylinder or grid is filled with a powder mainly containing an active material, or a method is applied in the form of a paste.

On the other hand, in the case of nickel-cadmium storage batteries, which are alkaline batteries, there are methods similar to those described above, or methods in which a sintered body is impregnated with a salt solution of the active material, and this is converted into the active material by electrolysis, thermal decomposition, chemical treatment, etc. It has been adopted. In order to retain the active substance q in the sintered body in such a method, it is necessary to repeat the impregnation and conversion with the salt solution several times to more than 10 times, making the process complicated. On the other hand, in the case of the method of applying 4-st to the grid, the manufacturing method is simpler compared to the case of holding it on a sintered body, and the support is a screen, extract, etc.
Continuous production methods were also possible using solid wood, dotaru, perforated plates, etc.

However, there are fewer contact points between the support and the active material than in the case of a sintered body, and the bonding strength is not sufficient, so the battery characteristics such as discharge performance and lifespan are not as good as those of a sintered body.

In addition, the coating method can be used by using a sintered body as the support.
However, in conventional sintered bodies, the pore diameter is small, ranging from several microns to several tens of microns.

On the other hand, the active material used for direct filling has a size of several microns to several hundred microns, and it has been impossible to uniformly fill the sintered body directly to the inside of the sintered body.

However, the sponge-like porous metal bodies that have recently been commercialized are porous bodies in which spherical pores are three-dimensionally connected, and any pore diameter can be selected from a few tens of microns to several digits.

Therefore, if the support is a sponge-like metal porous material having a pore size that matches the particle size distribution of the active material to be filled, the coating method can be employed.

In other words, if a mixture of an active material, a conductive material, and an additive is filled in a single strip inside a sponge-like porous metal material, the active material is directly filled in the form of the active material, which is different from adding it in the form of a salt. Unlike this, it does not require conversion treatment and the manufacturing process can be simplified.

As an application example of this method, we have proposed a nickel positive electrode for alkaline storage batteries. In the case of a nickel positive electrode, the active material nickel hydroxide is a powder with a distribution of several microns to 20 Ott kζ, which is mixed with nickel powder and Co/Z)reto powder and made into a drop shape with a pore diameter of several tens to several microns. After filling the inside of a sponge-like metal porous material with a distribution of 100 microns, it is dried, added with a binder, and pressurized to form an electrode plate. A nickel-cadmium storage battery composed of this positive electrode and a cadmium negative electrode has characteristics equivalent to or higher in capacity than a battery constructed using a conventional nickel electrode using a sintered body as a support (F
I'll be beaten.

However, the electrode plate was manufactured through the following process.
The drying and pressurizing process was not necessarily suitable for mass production.

That is, it was produced through the following steps: 1. Filling the porous body with yeast; 2. Drying (complete drying); 2. Adding a binder; 2. Drying (half-cut drying) (5) Pressure (using a flat plate press). If the drying is completely performed during this pressurization, there is a risk that the skeleton of the sponge will be destroyed by the force.
Next, dry the water content to a value suitable for Calo pressure, that is, 15 ~
This was done after adjusting the moisture content to 20%. However, if the thickness of the porous body and the moving speed are changed at this time, it is necessary to set appropriate drying conditions, which is complicated. For 75 years,
Since it is not always possible to adjust the water content to the optimum value, an adjustment step may be required as a pretreatment during pressurization. The porous material is sandwiched between water-absorbing cloth or paper and pressurized to adjust the water content to the optimum value.

Therefore, the pressurization process requires a lot of time, and
Since the work is intermittent and the drying process before that is complicated, it is not suitable for mass production, and improvements have been desired.

The present invention has focused on the fact that when a multilayer body filled with a paste-like active material is subjected to appropriate pre-pressurization, its liquid content can be adjusted to a value suitable for the actual Calorie pressure. That is, when a porous body filled with a strut-like active material is subjected to a force I1), liquid is discharged from the porous body, and the amount thereof is proportional to the degree of the force IIB2. For example, when a porous body of a nickel electrode with a porosity of 95 cm is filled with 4-st with a liquid content of approximately 30%, the thickness of the porous body at the time of filling is 80%! It has been found that if pressure is applied to a thickness of +1, the liquid content can be adjusted to 15 to 20%, which is optimal for main pressurization. The "F-ring pressurization" can pressurize a long porous body filled with active material at °C, and it is easy to remove the liquid coming out of the porous body and remove the deposits on the press surface. From the r'-A of Sato, it was determined that the method using a roller press is suitable, and the method using a flat plate press is suitable for the wooden sword 11 pressure.

In other words, the capacitance density when the porous body is filled with the active material in a single strip is about 350 mAh/crn3, and if the electrode plate is filled with the active material, it is about 500 mAh/crn3.
When a sponge-like porous metal material is pressed with a roller grip with a force of 1J, the above problem does not occur up to around 450 mAh/cm3, but the problem occurs when the capacitance density is higher than that.
If one pressure is applied, the porous body will elongate and cracks will occur75; therefore, it is not appropriate to employ a roller grip for one pressure of this horn.

Therefore, it was found that the best method is to use a roller press for preliminary pressing and a flat plate press for main pressing.

Next, in the production of electrode plates, the porous body should be pressurized either immediately after filling with the mustard or after adding the binder in the conventional manufacturing method. There is almost no active material adhering to the pressure surface, and even if it does, it is easy to remove. Furthermore, since a portion of the liquid in the porous body is removed by pressurization, the drying efficiency is higher than that of the latter.

On the other hand, in the latter case, the mixture of active material and binder adheres to the pressurized surface, which requires removal work, and the drying process is performed with the porous material containing a large amount of liquid, which consumes more energy than the former case. The quantity will be large. Therefore, it is better to apply pressure immediately after filling the paste.

Hereinafter, a nickel electrode will be described as a specific example.

The support of the example active material was made of nickel, had a structure shown in FIG. 1, had a thickness of 10 mm, a porosity of 95, and a pore diameter of 50 to 30
A spono-like porous material with a diameter of 0μ was used.

In the figure, 1 is a core portion 2, and 2 is a hole portion.

A mixture of 85 wt% nickel hydroxide, 10 wt% nickel powder, and 5 wt% cobalt powder was added to the porous body.
% CMC aqueous solution to form a yeast having a water content of 30 wt %, the mixture was uniformly filled, and the yeast adhering to the surface was removed to obtain an active material-filled porous body. This porous body has an active material with a water content of approximately 30%, a porosity of approximately 5%, and a sticky surface. 20 of this
It was cut into a size of 0 x 500 mm and used as an electrode plate using the method of the present invention and the conventional method.

First, an electrode plate was fabricated by the method of the present invention shown in (A+) in FIG. 2 by gradually changing the pressure conditions of the preliminary pressurization using a roller grip, and the state of the porous body was observed.The results are shown in Table-- As shown in Table 1, it is clear that the pressure applied by RollerGres is wire processing unlike that of flat plate Sores, so it is easy to damage the porous body, and the safe degree of application is limited in the case of nickel electrodes. 11; Density: 450 mAh/cm3
It is before and after, and if it is more than that, cracks and cuts will occur. Therefore, the limit was set at a thickness of about 80% of the thickness at the time of filling the pressure flap with a roller press.

Table 1 Next, main pressurization was performed using a flat plate of Zores, dried, and the binder (4
Addition of fluorinated ethylene suspension) and drying to reduce the thickness to 0.
．． A 7 mm electrode plate manufactured by the method of the present invention was used.

On the other hand, in the conventional method shown in Fig. 2 (Bl), the electrode plate was prepared by completely drying the porous body filled with the active material, adding a binder, semi-drying it, and pressing it with a flat plate press. Dry, 0
．． An electrode plate of 7 wn was obtained. In this case, the total time required for drying to obtain an electrode plate was about 18 minutes at a temperature of 100° C., whereas with the method of the present invention, it could be significantly shortened to about 10 minutes under the same conditions. In the conventional manufacturing method, the binder and active material adhered to the pressurized mold during pressurization, and it was necessary to remove the adhered materials each time pressurization was applied, but in the case of the present invention, the porous mold was removed during pressurization. Since the body does not contain a binder, the active material that adheres to the roller press during pre-pressing can be easily removed, and it rarely adheres to the flat plate press during main pressurization, and even if it does, it can be easily removed. Almost no maintenance work was required. When an electrode plate is manufactured according to the manufacturing process of the present invention,
This makes it possible to improve efficiency by approximately 20% compared to conventional manufacturing methods.

At the same time, six AA and sealed nickel-cadmium storage batteries were manufactured using these electrode plates as positive electrodes and cadmium electrodes as negative electrodes.

The battery using the electrode plate manufactured by the method of the present invention is designated as (a), and the battery manufactured using the conventional method is designated as (bl).The battery is charged at 1/10C.

The initial capacity (al2
470~2580mAh, (bl2460~2580
mAh, now after about 500 charge/discharge cycles (a
l 2400~2520mAh (bl 2400~
At 2500 mAh, there was almost no performance deterioration in any of the batteries, and no influence of changing the pressurization timing in the production of the %-electrode plate was observed.

As described above, the electrode plate manufacturing method of the present invention can be applied to two pressurized [
In addition to improving workability, the time required for the drying process is significantly shortened, and the effect of promoting mass production of electrode plates is very large.

[Brief explanation of the drawing]

Fig. 1 is an enlarged view of a sponge-like porous metal body used in an embodiment of the present invention, Fig. 2 (A) is a schematic diagram of the manufacturing process of an electrode plate showing an embodiment of the present invention, (Bl is a schematic diagram of the manufacturing process of an electrode plate showing a conventional manufacturing method. 1... Core material part 2, Kel, 2... Hole part.

Claims (1)

[Claims] In a battery electrode plate in which a sponge-like porous metal material is used as a support for an active material, after filling the inside of the porous material with the active material in the form of a strip, pressure is applied using a roller press and then a flat plate press before a drying process. A method for manufacturing an electrode plate for a battery, characterized by providing a process.