JPS6151636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode plate for an electrolytic cell, and more particularly to an electrode plate for an electrolytic cell using a synthetic resin material containing a conductive substance.

2. Description of the Related Art Conventionally, a stacked electrolytic cell is known in which a positive electrode chamber and a negative electrode chamber are stacked with a diaphragm interposed in between synthetic resin plates provided with electrolyte flow holes. FIG. 1 shows a typical example of such a stacked electrolytic cell, which includes a diaphragm 5,
It is composed of a frame-shaped spacer 1 and a plate-shaped electrode 3 containing a conductive material laminated symmetrically on the negative electrode side and the positive electrode side (only one side is shown) with the diaphragm 5 and the frame-shaped spacer in between. The positive electrode solution (or negative electrode solution) is supplied through the electrolyte flow hole 6A of the plate electrode 3.
It flows from the frame space 2 of the spacer 1 above onto the electrode surface, and then flows to the outside or the next electrolytic cell from the communication hole in the other frame space. On the other hand, the negative electrode liquid (or positive electrode liquid) is supplied through spacers (not shown) installed symmetrically across the diaphragm 5 from the flow hole 6B.
Similarly, it flows in and is discharged from the space within the frame.

The electrode plate used in the electrolytic cell has electrical conductivity by containing a conductive substance, but in such an electrode plate, if the entire area of the plate is a good conductor of electricity, the electrolyte flow path is The drawback is that current leaks outside the electrolysis chamber. Such leakage current is not a current passing between the electrodes of the electrolytic cell, but is normally not involved in the intended electrolytic reaction (or battery reaction) and becomes ineffective power.

An object of the present invention is to provide an electrode for an electrolytic cell that can eliminate the drawbacks of the prior art described above and can reduce leakage current from the electrolytic cell as much as possible.

In order to eliminate as much as possible the factors that reduce the electrical resistance of the electrolyte flow path, the present inventors reduced the amount of conductive material contained in the electrode plates in the electrolyte flow path outside the electrolytic chamber, thereby increasing the electrical resistance of the electrolyte flow path. The present invention was achieved by discovering that the resistance increases and the leakage current decreases.

The present invention provides an electrode plate for an electrolytic cell made of a synthetic resin containing a conductive substance, in which the content of the conductive substance in the liquid flow path outside the electrolytic chamber is 70% of the content in the electrolytic chamber.
It is characterized by the following.

The present invention applies not only to electrolytic cells but also to batteries having the same configuration as electrolytic cells, so the term electrolytic cell or electrode plate in this specification is synonymous with battery or electrode plate, and of course , within the scope of the claims.

In the present invention, examples of the conductive substance contained in the resin include electron conductive substances such as carbon powder and metal powder, as well as substances having hole and ion conductivity, such as various semiconductors and solid electrolytes.

The synthetic resin forming the electrode plate of the present invention may be any material as long as it can form the electrode plate, such as synthetic resins such as polyethylene, polypropylene, polyvinyl chloride, polycarbonate,
Examples include minerals that can be molded into sheets and have properties similar to resins. The amount of the conductive substance contained in the synthetic resin may be an amount that provides sufficient conductivity for electrolysis or reaction, and in the case of metal powder, for example, it is about 50% by weight or more. In the present invention, it is preferable that the synthetic resin surrounding the electrolyte flow path outside the electrolytic chamber does not contain a conductive substance, but it does not substantially contain 70% by weight or less (preferably 50% by weight or less) of the electrically conductive part. However, the electrical resistance becomes sufficiently large and the object of the present invention can be achieved. It is preferable that the conductive substance is uniformly contained in the resin in the electrode chamber portion.

In addition, when manufacturing the electrode plate, for example, synthetic resin containing a large amount of solid electrolyte is brittle and difficult to process.
Although it is also difficult to tighten with bolts, etc., the peripheral area of the electrode plate (electrolyte flow area) does not contain a large amount of solid electrolyte and is relatively easy to process, which is advantageous in terms of manufacturing, and strength reduction is also an issue. It won't happen.

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

Example 1 An electrolytic cell was fabricated by stacking bipolar plates shown in FIG. 2. As shown in Figure 2, the synthetic resin sheet of the bipolar plate is a fluororesin binding sheet that contains carbon powder at both ends of the sheet, including the liquid flow holes, in an amount of 40 to 60% by weight of the central portion. A single electrolytic cell was constructed by stacking the spacer and the diaphragm. Two of these single electrolytic cells were stacked together to form a bipolar electrolytic cell. Note that when measuring leakage current, a soft polyvinyl chloride sheet was used instead of the diaphragm to electrically insulate the diaphragm portion. The electrolytic cell was filled with 1 mol/aqueous sodium chloride solution, and the electrical resistance between both bipolar plates was measured using an AC bridge method and a circuit tester. The same applies to the case of using a bipolar plate shown in Fig. 2, which has grayish-white ends and contains almost no carbon powder, and for comparison, the case of using a bipolar plate containing almost uniform carbon powder over the entire area of the bipolar plate. We considered this. As a result, assuming that the resistance is 1 when both ends of the bipolar plate contain carbon powder uniformly like the center, then when it contains 40 to 60% by weight,
10, and those containing almost no amount were 12. As a result, it has become clear that the leakage current flowing through the electrolyte flow path is significantly reduced by the present invention.

FIG. 3 is a perspective view of a bipolar plate showing another embodiment of the present invention. In this case, in addition to the electrolyte flow holes 10 in the peripheral portion, the flow holes 11 are formed in the central portion,
The content of the conductive substance in the resin in the central portion is also reduced, similar to that in the peripheral portion. Even with such a configuration, leakage current can be reduced similarly to the first embodiment. Furthermore, even if a large number of communication holes are formed, since the conductive material is not contained in those portions, the strength, durability, etc. will not be adversely affected.

As described above, according to the present invention, since the peripheral portion of the liquid flow hole of the plate electrode has a relatively high electrical resistance, the leakage current flowing from the peripheral portion of the electrode plate through the conductive frame, the holder, and the solution can be significantly reduced. can be reduced to In addition, a large amount of conductive material is present in the central part of the plate-like material that constitutes the electrode, and there is less (or no) conductive material in the peripheral part where there are many processed parts such as liquid flow holes, so the electrode material has weak strength. (matrix material) can be used satisfactorily, and durability is also improved.

[Brief explanation of the drawing]

FIG. 1 is a developed view showing an example of a liquid flow type electrolytic cell in which a plate-shaped electrode of the present invention is used, and FIGS. 2 and 3 are perspective views of plate-shaped electrodes each showing an example of the present invention. It is. Code 1 in the figure is a spacer,
3 is a (plate-shaped) electrode, 5 is a diaphragm, and 10 and 11 are liquid flow holes.

Claims (1)

[Claims] 1. An electrode plate for an electrolytic cell made of a synthetic resin containing a conductive substance, characterized in that the content of the conductive substance in the liquid flow path outside the electrolytic chamber is 70% or less of the content in the electrolytic chamber. Electrode plate for tank.