JPS5833668B2 - Manufacturing method for battery electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery which continuously fills the voids of a metal porous body (hereinafter referred to as foamed metal) with a three-dimensional structure having continuous voids with a paste-like active material. Concerning a method for manufacturing electrodes.

Currently, the typical electrode for alkaline storage batteries is a sintered electrode.

This electrode is made of sintered nickel powder with a porosity of 70 to 80.
% substrate is filled with active material by impregnation with active material salt and conversion to active material by electrolysis, thermal decomposition, etc.

This active material filling process is complex and requires repetition, so there is a demand for its rationalization.

There is a paste type electrode as an electrode with a simpler active material filling process.

This is made by applying a paste-like active material containing a binder to a core material such as a metal net or perforated plate.

In this electrode, the active material is held in the core material by a binder, so it often falls off, and since the electrode is a two-dimensional core material, it cannot hold a large amount of active material.

Therefore, attempts have been made to use foamed metal with a three-dimensional structure in place of the above-mentioned core material.

That is, this is a method of manufacturing an electrode by rubbing and filling a paste-like active material into the voids of a foamed metal from its surface, and then compressing the material with an appropriate pressure.

As is already known, foamed metal has a higher porosity than a sintered substrate, and the pores that form the voids are larger in diameter, so it is possible to fill it with active material powder in the form of a paste. It is possible to increase the density by compression operation after filling.

Furthermore, since the active material is seeped through the three-dimensional framework of the foamed metal, there is very little chance of the active material falling off, unlike in conventional paste-type electrodes.

In this way, electrodes using foam metal can be expected to have high capacity and high density because filling with active material is relatively easy.

In order to continuously fill this foamed metal with active material, a long strip of foamed metal is placed in a position where it will come into contact with the paste-like active material, and a reciprocating rubbing tool is used to rub the upper surface of the foamed metal with the paste-like active material. It is easiest to rub together.

In view of the fact that the rubbing speed greatly influences the active material filling efficiency in a method of filling an active material by a rubbing operation using a rubbing tool, the present invention aims to improve the active material filling efficiency through an optimal rubbing speed. It is something.

That is, in the present invention, when the amplitude of the rubbing tool is aCTL and the movement cycle of the rubbing tool is X times/second, the rubbing speed of the rubbing tool ycIrL/second, which is expressed by equation 1, is set to satisfy equation 2. It is something.

y=2ax ・・・・・・・・・(1)
11-≦y≦64 (2) The present invention will be explained below with reference to Examples.

FIG. 1 shows the configuration of an active material filling device.

1 is a foamed metal, 2 is an active material container, 3 is a stirrer, 4 is a paste active material, 5 is a porous plate, 6 is a rubbing tool with a brush, 7 is a driving morph of the rubbing tool, 8 and 9 are foamed metal This is a drive roller for moving the .

Commercially available nickel hydroxide powder was used as the active material, and
Approximately 10 weight of nickel powder was added as a conductive material and mixed and stirred. Next, an appropriate amount of water or an aqueous solution of carboxymethyl cellulose was added and further stirred to form a paste.

This active material was placed in a container 2, and the stirrer 3 was driven to mix it thoroughly, and the amount of the active material was adjusted so that the active material rose above the porous plate 5 supporting the foamed metal 1.

On the other hand, the foamed metal was impregnated with an appropriate amount of water and then gradually moved to an active material filling device using a driving roller 8.

In this way, the foamed metal 1 moves through the paste-like active material 4 which is being stirred by the stirrer 3, while its upper surface is rubbed together with the active material by the rubbing tool 6 operated by the drive motor 7.

Through this operation, the active material is filled into the voids of the foamed metal while being replaced with water and air.

The foamed metal filled with the active material is then moved to the next step with the addition of a driving roller 9.

The foam metal used here is made of nickel and has a width of 60 mm.
, length 2m, thickness 2.4mm, porosity approximately 96φ.

In addition, the internal volume of the active material-filled part of the container is approximately 101, the weight of the paste active material is approximately 15,2, and the rotation speed of the stirrer is 1.
~2 rotations/second, and the moving speed of the foam metal is 0.5 mm.
/second.

The water content inside the foamed metal was adjusted to about 40% by volume, and the water content of the paste active material was adjusted to about 30% by weight.

Under these conditions, the rubbing speed of the rubbing tool that rubbed the upper surface of the foamed metal together with the active material was varied, and the filling rate of the active material at that time was measured.

Five neoprene rubber plates of three thicknesses were used for the brushing of the scrubbing tool, and the scrubbing speed y was adjusted by changing the length of the amplitude a or the number of cycles X.

FIG. 2 shows the relationship between the rubbing speed y and the active material filling rate when the amplitude a=8 and constant.

As is clear from the figure, when the value of y is 11 or more, a practical active material filling rate of 80% or more can be obtained.

When the rubbing speed is increased, the filling rate increases, and at y=32, the filling rate becomes 100φ.

Furthermore, when the rubbing speed is increased, more resistance than necessary is applied to the surface of the foamed metal, which crushes the pores on the surface of the foamed metal and reduces the porosity of the surface, making it difficult to fill the active material and increasing the filling rate. gradually decreases.

Furthermore, when the rubbing speed increases, strong stress is applied in the direction opposite to the direction in which the foam metal moves, which deforms the foam metal and makes it difficult to move it normally.

This limit was y-65.

From the above, in order to ensure a practical active material filling rate of 80φ or more, the value of y needs to be 11 to 64, and the corresponding value of X is 0.7 to 4.

Here, the amplitude a and the number of cycles X are inversely proportional, and the amplitude is 2
When the number of cycles is doubled, the number of cycles becomes 1/2.

Since the value of the amplitude a cannot be made infinitely large, it is natural that it is regulated by the size of the active material filling device.

In other words, as a increases, not only does the active material filling device become larger, but stress is added in the direction of travel of the foam metal, but in the opposite direction, stress is added in the opposite direction to the travel direction. It takes longer.

Because of this stress, more tension than necessary is applied to the foamed metal and there is a risk of damage, so it is better not to apply it in the opposite direction for too long.

Therefore, in order to reduce the abnormal tension in the foamed metal and avoid increasing the size of the active material filling device, it is preferable that the range is 0<a≦30.

An amplitude of 0 means that the rubbing tool is stopped, so this is impossible.

If the value of a is very small, this is when X becomes large and a type of vibration phenomenon is occurring.

Even in such a state, the active material is filled into the foamed metal, and the filling efficiency maintains approximately 80 weight φ or more.

Therefore, the active material can be filled by applying a rubbing tool together with the active material to the upper surface of the foamed metal to generate a vibration phenomenon.

Furthermore, if a is larger than 30, the entire device becomes large as described above, which not only causes a major problem in device design, but also causes damage to the foam metal.

Moreover, if the rubbing speed is increased, the degree of rubbing becomes so great that loading of the active material becomes impossible.

Next, the foamed metal filled with the active material according to the optimal method of the present invention was cut into pieces of 6 x 30 CrrL in size, and the amount of active material filled in several pieces was determined, and it was found that each piece was approximately 8.
0±4 g, and even when the value of a was very small and the rubbing tool was operated in a vibrating state, it was about 70 g.

On the other hand, when the active material mixed well with a rubber-based resin binder is applied to a metal net of the same size and then pressed with a roller press from both sides, the filling amount is approximately 50 ± 10 g.
The range of fluctuation was also wide.

In addition, although the above example shows an example of rubbing with a neoprene rubber plate, the rubbing tool may be any tool that has the effect of pushing the active material on the top surface of the foamed metal into the voids of the foamed metal by a rubbing action. May be used.

As described above, according to the present invention, a foamed metal can be efficiently filled with a paste-like active material, and a high-capacity, high-density electrode can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of an active material filling device used in an example of the present invention, and FIG. 2 shows the relationship between rubbing speed and active material filling rate. 1... Foamed metal, 4... Paste active material, 6... Rubbing tool.

Claims (1)

[Claims] 1. A porous metal body having a three-dimensional structure having continuously connected voids is placed in a position where it comes into contact with a paste-like active material, and the upper surface of the porous metal body is rubbed together with the active material. In the step of filling the voids of the metal porous body with active material by rubbing with a tool, the amplitude of the rubbing tool is acrrL, the number of movement cycles of the rubbing tool is X times/second, and the rubbing is expressed by the formula y = 2 a x The rubbing speed by the tool yc′IrL/sec is 11≦y≦64
A method for manufacturing a battery electrode characterized by the following. 2. The method for producing a battery electrode according to claim 1, wherein a is 30 or less.