JPS6322016B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention improves electrode plates such as electrode plates for various batteries by applying a special electrolytic treatment effect to the electrode plates in which a paste-like active material is held in the current collector. The present invention relates to a suitable new electrode plate electrolysis method and apparatus.

Generally, battery electrode plates are made by holding an active material in a current collector mainly made of metal to form the base of the electrode plate, then drying this, and then incorporating it into a battery case, or by chemically processing it in the plate state. Built into the battery case,
Normally, the plates are submerged in a rich electrolyte and polarized either positively or negatively to produce a battery-functioning plate.

By the way, in this type of electrode plate, the active material may apparently cover the current collector, but in reality, there are parts of the porous body that are not completely covered with the active material, and especially in the positive electrode, the pores of the current collector are The parts exposed to the inside are particularly susceptible to oxidation and erosion, and sometimes the current collector disappears or breaks.

In order to suppress such a phenomenon, the present inventors used a solution in which oxidation-resistant fine powder was dispersed, using the zeta potential formed by ions coordinating with the fine particles to We proposed a method to form a protective layer or film by electrochemically electrolytically depositing even the smallest particles preferentially on the surface of the current collector that is exposed inside the pores. That is, fine particles are dispersed in a solvent containing almost no electrolyte, and the current collector of the electrode plate is dispersed in a positive or negative direction in a state where the active material has virtually no discharge ability. This effect can be expected for both alkaline and acid batteries, and on the other hand, this treatment does not need to be carried out for a long time.

Furthermore, in lead-acid batteries, for example, lead-calcium alloys with high hydrogen generation overvoltage have recently been used as current collectors due to the demand for maintenance-free storage, and their structures have changed from conventional cast grids to expanded metal and perforated plates. Things are changing. In connection with this technology, we are particularly concerned with the early deterioration phenomenon that occurs during deep discharge cycles, which seems to be due to the properties of this alloy. In some cases, the present inventors have found that chemical formation in water containing almost no electrolyte is effective. In this case, the purpose is to form a strong oxidation layer that is unlikely to cause deterioration on the exposed surface within the pores of the current collector or at the interface between the active material and the current collector. At this time as well, if the electrolytic treatment is carried out for a long time, it may be difficult to obtain an active material that exhibits excellent rapid discharge characteristics, so it is often better to carry out the treatment in a short time.

In this case, although electrolysis is performed in the same way, the purpose and treatment method will need to be significantly different from the conventional chemical conversion treatment, which changes an active material into a substance that causes an electromotive reaction. In other words, if the above method is adopted during the battery cell formation stage of conventional chemical formation, a liquid different from the normal chemical liquid is put into the battery for short-term electrolysis, and the liquid must be changed after formation. The need arises. Furthermore, it must be taken into account that adding substances that are unnecessary for the discharge reaction may adversely affect the battery characteristics. On the other hand, in the chemical conversion method in which a separate chemical conversion tank is provided, two or more chemical conversion tanks of the same size as conventional methods are required for short-time special electrolytic treatment. In addition, in managing the processing solution, particularly in the case of processing such as precipitation of fine particles by electrolysis, it is difficult to uniformly disperse particles that are consumed or settled at all times.

From these points of view, it is desirable to have an electrolytic treatment device that can achieve the same effect quite simply, rather than placing it in a battery tank or electrolytic bath as in the past, and it is preferable to process it with bare electrode plates. .

From these viewpoints, the present invention has departed from the conventional idea that electrolysis is carried out in a battery container, and has invented a completely new electrolytic treatment apparatus.

That is, the present invention provides an electrolytic terminal for press-contacting an unfinished electrode plate to an exposed current collector of the electrode plate in a wet state of a pasty active material without using a battery case to electrically conduct the electrode plate; It is characterized in that electrolysis is carried out by applying an electrolytic voltage between the current collector and a counter electrode for electrolysis, which is not directly electrically conductive but is ionically electrically electrically electrically electrically connected via a liquid that wets the inside of the electrode plate. With this configuration, the electrolytic treatment can be carried out efficiently in a bare state, especially in the process up to transporting the electrode plate to the battery case.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figures 1 and 2 show examples of electrode plates in which a paste or slurry active material is applied to the current collector, such as in paste-type lead-acid batteries and paste-type alkaline batteries. , when applied to screens, perforated plates, etc. a
is a current collector, b is a coating layer of active material, and generally a non-coating portion c is provided for taking out the terminal.

FIG. 3 shows an example of an electrode plate obtained by applying an active material layer b' to a cast grid a', in which two electrode plates are formed. Here, too, there is a non-applied portion c'. When the coating amount is small, a portion of the current collector may be exposed on the surface of the active material layer.

In addition, there are also structures in which the current collector itself has a porous skeleton structure in which an active material is packed by chemical impregnation or thermal decomposition, especially in the case of electrode plates for alkaline batteries. In this case, a part of the current collecting porous body is often exposed on the surface,
In order to take out the terminal, measures are taken such as pressing the peripheral part to create a part where the active material does not enter, or welding a non-porous conductor to the current collector in advance.

Now, on the surface of the electrode thus obtained, the current collector or, as an extension of the current collector, a conductor portion connected to the current collector and a porous body of active material are exposed.

FIG. 4 shows the configuration of a basic apparatus for applying electrolytic treatment to these electrode plates. 1 designates an electrode plate as described above to be electrolytically treated. Reference numeral 2 denotes a pedestal, on the top of which is provided an electrode support 3 made of an insulator such as plastic, and in the center of which is provided a counter electrode 5 for electrolysis whose periphery is protected by an insulator 4.
6 is a conducting wire of the counter electrode 5. Reference numeral 7 denotes a frame provided on the pedestal 2, on which an electrolytic terminal 9 protected by an insulator 8 is provided, and is adapted to be pressed against the exposed portion of the current collector on the electrode plate 1. . It is preferable to use biasing means such as a spring to press the terminal 9 into contact with the current collector. 10 is a conductive wire of the terminal 9. Although the electrode plate 1 supplied on the support stand 3 can be placed directly on the counter electrode 5 for electrolysis, in this example, a non-conductive porous body 11 is provided on the counter electrode 5.

Direct contact of the electrolytic counter electrode 5 with the active material layer of the electrode plate 1 generally means that if the active material of the electrode plate before chemical formation is a non-conductive material such as lead sulfate or nickel hydroxide, it will become a conductor in a short period of time. However, since a part of the current collector is often exposed on the surface of the active material layer, it is recommended to place a non-conductive porous body 11 between the electrode plate and the counter electrode. good. In this structure, if the electrode plate is in a wet state, even if the porous plate 11 is used, the liquid in the electrode plate will move and accumulate in the porous body 11 during continuous processing operations, and the liquid in the electrode plate will be transferred to the porous body 11 and accumulated prior to processing. The porous body is also moistened by keeping the body 11 moist with a liquid used for electrolysis. With such a structure, whether directly or indirectly, the electrolytic counter electrode 5 is ionically connected to the liquid in the electrode plate.

Either moisten the electrode plate in advance as described above, or
When electrolyzed in a wet state inside the device,
Electrolysis occurs between the current collector in the electrode plate and the counter electrode for electrolysis using the liquid present inside the porous body as a medium. These polarities can be selected as necessary, or alternating current, alternating current and direct current, or direct current can be selected as necessary. The ability to perform electrolytic treatment after forming the active material layer in this way is particularly effective in modifying the surface of the current collector exposed at the interface between the active material and the current collector or in the space within the porous body, and is also quick and effective. In terms of processing time, you can easily complete the task without having to put it in a container.

FIG. 5 is basically the same as FIG. 4, but is an example of a configuration in which the counter electrode 5 is pressed from the top surface of the electrode plate, and the current collector is included in the entire surface of the electrode plate, so the counter electrode 5 is pressed from the top surface of the electrode plate. There is no need for terminal 9 to face each other.

On the other hand, the electrolytic terminal 9 that presses the current collector of the electrode plate is a roller electrode as shown in FIG.
If a method is adopted in which the terminal 9 is made a conductor or a live electrode is brought into contact with the terminal 9 separately, there is less risk of damaging the electrode plate. The same thing can be said for the counter electrode side, and the counter electrode 5 is a roller type, a non-conductive porous body 11 is provided around it, and the support 13 is used as a current-carrying path, or a separate conductor 14 is connected to the counter electrode 5. It is effective to have a structure that allows FIG. 7 shows an example of the structure of an electrolytic counter electrode in which a counter electrode 5 is fixed in a drum shape on a roller body 15 and a porous body 11 is provided on top of the counter electrode 5.
is provided with electrical continuity by a brush 16. The electrode plate 1 passes under this and receives electrolysis. Reference numeral 17 denotes a pedestal on which the roller body 15 is pivotally supported.

FIG. 8 shows an example in which the electrolytic terminal 9 and the counter electrode 5 are set on the same roller. Reference numeral 18 denotes a frame provided with a shaft 19, an insulator 21 is fixed to a fixture 20 fixed to the shaft 19, and a drum-shaped counter electrode 5 is disposed separately on the left and right, and a non-contact material is provided on the surface of the counter electrode 5. A conductive porous body 11 is provided. In this example, an electrolytic terminal 9 is arranged in a ring shape in the center, and the terminal 9 and the counter electrode 5 are energized from brushes 22 and 23, respectively. The conduction between the left and right counter electrodes 5 is short-circuited through the insulation 21. The roller 24 is used to prevent damage caused by sliding of the lower part of the electrode plate and to increase the smoothness of feeding, and the electrode plate is configured to pass between the terminal 9 and the counter electrode 5 and the roller 24. In this configuration, electrolysis is performed while being held between the rollers.

Next, it is also possible to wet the electrode plate itself externally before transporting it to the electrolytic section, but since this is time-consuming, a conduit 26 is always used from the liquid tank 25 to the porous body 11 placed on the surface of the counter electrode. The liquid 27 may also be supplied. The liquid amount can be controlled arbitrarily during this period. 8th
The format shown in the figure happens to be designed to be applied to a device in which the conductor portion of the current collector is located in the center of the electrode plate to be electrolyzed, as shown in FIGS. 1 and 2, and its position can be changed as required.

On the other hand, regarding the supply of liquid, it is possible to directly infiltrate the electrode plate or moisten it with a shower during the process of conveying the electrode plate, but as shown in FIG. The method of transferring is convenient for process control. This can be done from above or below. In addition, as shown in Fig. 4, when the counter electrode is located below, a liquid tank is provided on the extension of the porous body 11 in either direction to keep the porous body constantly moistened by surface tension and supply the components necessary for electrolysis. be able to.

Another important point in FIG. 9 is that the electrolytic terminal 9 and the electrolytic counter electrode 5 are separated from each other in the transport direction of the electrode plate. This is applied when the electrode plate is still long. There is no particular difference in the positional relationship between the front and back. When the electrolytic terminal and the counter electrode are close to each other, in addition to the electrolytic current between the current collector and the electrolytic terminal, the current flowing between the electrolytic terminal and the counter electrode increases due to impedance, and the electrolytic terminal itself In the case where the conductive material corrodes, becomes immobile, or deposits fine particles, non-conductive fine particles are deposited, increasing the need for maintenance. In either case, as long as the terminal 9 is in contact with the current collector of the electrode plate, the current collectors in successive electrode plates are charged, and the impedance of the electrolyte varies depending on the distance from the counter electrode. As a result, the strength of electrolysis in the transport direction changes. In other words, if it is far from the opposite pole 5, it will be small whether it is before or after it, and as it gets closer, it will become larger.
It becomes maximum near the opposite pole. Note that 30 is a pedestal.

A long unformed plate of the lead battery electrode shown in Figure 1 was moistened with a 1 mol/aqueous solution of sulfur salt, and the voltage was set at 2.4V.
The intensity of the electrolytic current when electrolyzed with the current collector was investigated using the method shown in Figure 9 from the difference in the voltage drop of the current collector, and the results are shown in Figure 10.
As shown in the figure. Although the distribution differs depending on the electrolysis voltage, the tendency is the same. From this, a special electrolytic pattern in which the current is gradually increased from a small current during the conveyance process, strong electrolysis is performed, and then attenuated can be realized without programming the voltage applied between the terminal 9 and the counter electrode 5. You can see that this can be done with a constant voltage. This means that when growing oxide film crystals on the surface of a current collector or depositing fine particles, strong and large crystals will grow first, and then dense crystals will grow in areas where there is insufficient space. You can expect it.

Note that if the purpose is to form a film by electrolytic oxidation in an almost neutral region, it is not necessarily necessary to apply a new electrolyte. For example, in the case of paste electrodes for lead-acid batteries, the applied paste retains sufficient moisture, the liquid is approximately neutral, and some lead sulfate is dissolved in the liquid. Therefore, although the resistance is large, the voltage is 10 to 20V.
If exposed to heat, oxidation of the current collector will occur little by little. Taking advantage of this situation, the present invention can be applied in the process of applying paste or slurry or in the process of filling before drying, and this effect will have a positive effect on the life characteristics of the resulting electrode plate. give.

As described above, the present invention departs from the idea that electrolysis is carried out in a liquid-rich battery tank, and is particularly suitable for preliminary short-time electrolytic treatment such as improving the properties near the current collector. It provides an electrolytic device that can be used widely, and its industrial value is great.

The materials of the various elements described above, the materials of the electrolyte liquid, the applied voltage, etc., depend on the purpose of the treatment,
It should be selected depending on the type of electrode, and there are no restrictions. In terms of safety, it is within a few volts when an electrolyte is applied, and a few volts when depositing fine particles that do not substantially contain electrolyte.
Since the work can be done at around 100V, there is no major danger. In other words, consider insulation from other equipment by cutting long items to an appropriate length as necessary. Adjustment of electrolysis time can be controlled by the speed of conveyance. Note that for a long object, at least a plurality of counter electrodes may be provided, or a terminal that rotates between a plurality of rollers in a belt manner may also be used.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an example of a paste-type electrode plate, Fig. 2 is a longitudinal sectional view thereof, Fig. 3 is a front view showing another example of an electrode plate, and Fig. 4 is an electrolytic device. FIG. 5 is a vertical cross-sectional view of another example, and FIG.
The figure is a front view showing an example of the configuration of an electrolytic terminal and a counter electrode, Fig. 7 is a side view with main parts cut out of the electrolytic counter electrode, and Fig. 8 is a side view with main parts cut out showing another example of an electrolytic device. FIG. 9 is a front view showing still another example, and FIG. 10 is a diagram showing the relationship between the distance to the counter electrode and the electrolytic strength during electrolysis. a... Current collector, b... Active material, 1... Electrode plate, 5
... Counter electrode for electrolysis, 9 ... Terminal for electrolysis, 11 ... Non-conductive porous body, 25 ... Liquid tank.

Claims (1)

[Scope of Claims] 1. An electrode plate comprising a current collector and a paste-like active material held therein is pressure-bonded to the active material directly or through a non-conductive porous material in a wet state of the paste-like active material. A method for electrolyzing an electrode plate, characterized in that electrolysis is carried out by passing current between the counter electrode for electrolysis and the current collector. 2 means for supporting a current collector and an electrode plate having a paste-like active material held therein; an electrolytic terminal that presses into contact with the current collector and provides electrical continuity; and a means for electrically connecting the current collector. An electrolysis device for an electrode plate, comprising: a counter electrode for electrolysis that conducts ionically by separating the liquid within the electrode plate without contact; and an electrolysis mechanism that conducts current between the terminal for electrolysis and the counter electrode for electrolysis. . 3. The electrode plate electrolysis device according to claim 2, wherein the counter electrode for electrolysis has a non-conductive porous material on its surface. 4. The electrode plate electrolysis device according to claim 2, wherein the electrolysis terminal is roller-shaped. 5. The electrode plate electrolysis device according to claim 2, wherein the counter electrode for electrolysis is roller-shaped. 6. Claim 2, in which the electrolytic terminal and the electrolytic counter electrode are provided on one roller insulated from each other.
An electrolysis device for the electrode plate described in Section 1. 7. The electrode plate electrolyzer according to claim 2, wherein the electrolytic terminal and the electrolytic counter electrode are provided separated from each other in the front and back with respect to the transport direction of the long electrode plate. 8. An electrolytic device for an electrode plate according to any one of claims 2 to 7, comprising a mechanism for supplying and wetting a solvent, an electrolyte solution, a dispersion of fine particles, etc. to the electrode plate undergoing electrolysis.