JPS6182676A - Sea water battery - Google Patents

Abstract

PURPOSE:To improve the reliability of a sea water battery by placing a separator made of pulp which can be decomposed by water between the positive and the negative electrodes. CONSTITUTION:A separator 4 which can be decomposed by water is made of pulp and prepared from paper. It is desirable that a binder or a hydration- resistant agent not be contained in the separator 4. The size of the separator 4 is adjusted to be either the same or as larger as possible than the size of the larger one of a positive and a negative electrode 2 and 3. The separator 4 is placed between the positive and the negative electrodes 2 and 3 in such a manner as to cover their facing surfaces. Accordingly, almost no short circuits develop during assembly of the sea water battery and therefore its reliability can be greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the improvement of seawater batteries, and its purpose is to improve the reliability of the batteries.

BACKGROUND OF THE INVENTION Conventionally, this type of battery generates electricity by being immersed in seawater. In other words, taking a silver chloride-magnesium battery, which is a common seawater battery, as an example, electricity can be extracted to the outside through a reaction in which silver chloride becomes silver at the anode and magnesium chloride at the cathode in seawater. I can do it. At this time, magnesium hydroxide is produced at the cathode while generating hydrogen gas as a side reaction. Magnesium hydroxide is passive and has low solubility, and when deposited in a battery, it leads to an increase in internal resistance, which not only makes it impossible to obtain high output but also causes a decrease in battery capacity. Therefore, the hydrogen gas (=
Therefore, it is necessary to adopt a structure that releases the gas to the outside of the battery. In other words, as shown in Figure 2, seawater batteries do not use separators such as those used in ordinary lead-acid batteries, Ninokerucadium batteries, or dry batteries, but instead use small glass balls or plastic strips, the so-called spacers 1. A so-called "seawater" is appropriately inserted between the anode 2 and the cathode 3 to adjust the distance between the electrodes and facilitate the flow of seawater within the battery.

Since the seawater battery that the invention seeks to solve has the above-mentioned structure, the anode and cathode are not completely separated over the entire surface, and in the area where there is no spacer, the two electrodes have a space between them (= We will face each other.

Therefore, when assembling the battery, the electrodes are easily short-circuited due to deformation of the electrode plates or pressurization of the battery, resulting in poor yield.

In addition, it is possible to check for short circuits when assembling cells, but it is difficult to check after stacking many cells and applying insulation coating, and it is difficult to check for short circuits when actually immersed in seawater. There were also cases where the short circuit did not occur, resulting in a lack of reliability of the battery (-).

The invention therefore aims to eliminate the above-mentioned drawbacks.

Means for Solving the Intervertical Vertex To achieve this objective, anode 2
A separator 4, which is decomposed by water, is placed between the cathode 3 and the cathode 3. The water decomposable separator 4 is made of a valve,
Although it is characterized by being a so-called paper, it is desirable that it contains no binder or waterproofing agent as much as possible. The separator 4 is cut to be the same size as the anode 2 or the cathode 3, whichever is larger, as much as possible. This cut separator 4 is inserted between the anode 2 and the cathode 3 (so as to cover the opposing surfaces of the two electrodes) when stacking the electrodes. Also, the separator 4 is made of water or a moisture absorbent such as silica gel or calcium chloride. Immerse it in a solution suspended in a solvent such as alcohol,
It can also be dried and used as a separator containing a moisture absorbent.

Function (2) The separator 4, which decomposes in water, acts as a separating member between the anode 2 and the cathode 3 to prevent short circuits during battery assembly, and after being immersed in seawater, it decomposes in seawater and It does not inhibit the release of magnesium oxide to the outside of the battery.Here, the meaning that the separator 4 is decomposed in seawater means that the separator 4
It is said that water separates into individual filaments9. In addition, in seawater batteries that use magnesium for the cathode 3, moisture in the air turns the magnesium surface into hydroxide during storage, which may delay the rise of battery voltage when immersed in seawater. By arranging a separator containing a moisture absorbent, moisture in the air can be removed, which prevents delays in battery voltage rise and also improves shelf life.

Example Two embodiments of the present invention will be described below.

Example 1 Paste reinforcing paper (F-15 manufactured by Abe Paper Industries, approximately 30 μm thick, used as a water-decomposable separator in the manufacture of lead-acid batteries)
m) was used. This separator is made of magnesium alloy plate (
3 wt %A - 1 wt Zn - balance Mg) was cut to the same size, the surface smaller than that size was sandwiched between a silver chloride plate reduced to silver and a magnesium alloy plate, and then pressed from both sides with a hydraulic press at 10 k/m. pressure was applied.

The resistance between the silver chloride plate and the magnesium alloy plate was 20 MΩ and hardly changed.

Example 2 A paste reinforcing paper (CRYSTEX Demon 8) with a slight wet strength was used as a water-decomposable separator. It was immersed in water in which calcium chloride fine powder was suspended (dipped twice, immediately pulled up, and dried with hot air to remove moisture absorbent). Created a separator.

A pressurization test was conducted in the same manner as in Example 1, but there was almost no change in resistance.

Example 3 A moisture absorbent-containing separator was produced in the same manner as in Example 2. This separator is made of hard vinyl chloride plate (I251
．． A unit cell a was formed by inserting a plurality of spacers 1 (5 stomachs x 0.2 rm height) between a magnesium alloy plate and a silver chloride plate to which a plurality of spacers 1 were attached. The parts other than the facing surfaces of the magnesium alloy plate and the silver chloride plate and the top and bottom of the cell were sealed with insulating tape 5. The openings at the top and bottom of the battery are seawater inlets and outlets 6.

For comparison, a conventional battery cell with the same structure but without a moisture absorbent-containing separator was also prepared. These batteries were left for 10 hours at a humidity of 90 degrees and a temperature of 40°C, then immersed in seawater, and discharged after 3 minutes (=150 mA/'N). Figure 3 shows the change in battery voltage at that time. It was found that the battery a of the present invention having a separator containing a moisture absorbent had little delay in voltage rise at the initial stage of discharge and had excellent storage performance.

Furthermore, the performance of the subsequent discharge was almost the same as that of the conventional product, and it was found that the moisture absorbent-containing separator decomposed and discharged (no adverse effects).

Effects of the Invention As described above, according to the present invention, short circuits during assembly of a seawater battery are almost eliminated, reliability is significantly improved, and electrode yield is also improved. (2) It has an extremely high industrial value as it has the effect of removing moisture from the air and improves the shelf life of seawater batteries.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a seawater battery according to the present invention, Figure 2 is a cross-sectional view showing the structure of a conventional seawater battery, and Figure 3 is a comparison of discharge performance between the battery according to the present invention and a conventional product. It is a discharge curve diagram of a unit cell. 2 is an anode, 3 is a cathode, 4 is a water-decomposable separator

Claims (1)

[Claims] 1) A seawater battery characterized by having a separator between an anode and a cathode that is decomposed by water. 2) The seawater battery according to claim 1, wherein the water-decomposable separator is made of a valve. 3) The seawater battery according to claim 1 or 2, wherein the water-decomposable separator contains a moisture absorbent.