JPH0564434B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technology for storing or supplying halogen molecules in a battery using halogen as an active material.

[Prior art]

Batteries using halogen as a positive electrode active material in combination with various metal reducing molecules and compounds as negative electrode active materials are conceivable. For example, there are zinc/chlorine type batteries, zinc/bromine type batteries, hydrogen/chlorine type redox batteries, etc., and the prior art will be explained using a zinc/chlorine type battery as an example.

FIGS. 1a, b, c, and d are schematic diagrams showing charging and discharging states of a zinc/chlorine type battery.

In the fully charged state shown in Figure 1a, the water or aqueous solution containing inorganic salts in the chlorine hydrate tank 1 is cooled to around 0°C, and the chlorine is stabilized as chlorine hydrate (ice-like solid). and stored. Zinc is precipitated as a metal.

During the discharge shown in Fig. 1b, the temperature of the chlorine hydrate tank 1 is gradually increased to decompose the hydrate and generate chlorine gas, which is blown into the electrolytic solution, dissolved, and supplied to the battery section. Reactions occur at the positive and negative electrodes.

Positive electrode Cl ₂ +2e→2Cl ^-Negative electrode Zn→Zn ⁺⁺ +2e At the negative electrode, metallic zinc becomes zinc ions and dissolves in the aqueous solution.

In the fully discharged state shown in FIG. 1c, most of the chlorine hydrate in the hydrate tank 1 is decomposed, and the temperature of the hydrate tank at that time is about 12°C. Zinc metal on the negative electrode becomes zinc ions and is dissolved in the electrolyte.

The chlorine generated during charging as shown in Figure 1d is approximately 10°C.
It is blown into water or an aqueous zinc chloride solution cooled to the following temperature to form a solid hydrate.

As mentioned above, in secondary batteries, halogens generated during charging are introduced into cooled water or an aqueous solution of metal salts, thereby converting them into Cl ₂ .8H ₂ O and Br.10H ₂ O.
The main method is to store it as a solid hydrate.

In addition, in the case of bromine rather than a hydrate, there is a method of storing it as a complex compound with a quaternary amine, and in the case of chlorine, there is a method of compressing it under pressure and storing it as a liquid in a cylinder.

[Problems with conventional technology]

When a halogen is converted into a hydrate or a complex compound, generally 10 to 20 Kcal/mol of heat of hydration or reaction heat is generated, and this heat must be removed to the outside in order to store the halogen. Furthermore, in order to supply halogen, heat must be supplied from outside because it absorbs heat during decomposition. In this way, heat must be taken in and out to the outside.
In each case, the accompanying water or aqueous solution must be cooled or heated, resulting in a large energy loss, which reduces the overall energy efficiency of the battery.

Furthermore, when a complex compound is formed with an organic compound, the organic compound used may mix into the electrolytic solution, contaminating the solution and deteriorating the electrode performance.

In addition, solid hydrates or solid complex compounds clog the blowing section, lowering the blowing function, and impeding water convection, making it difficult to efficiently absorb a large amount of halogen into water or an aqueous solution.

Even when pressurized and compressed and stored in cylinders, compressor power, pressure vessels, etc. are required, which is disadvantageous in terms of energy and equipment.

[Purpose of the invention]

The present invention was obtained as a result of intensive research to overcome the drawbacks of the prior art, and it reduces the power required during operation of the battery, improves the overall energy efficiency of the battery, and stores halogen as a homogeneous solution. The purpose is to develop a method.

[Structure of the invention]

The present invention is a battery having a positive electrode and an aqueous electrolyte using halogen as an active material, and is characterized in that the halogen is dissolved in hexachlorobutadiene and stored or supplied.

[Effect]

The key point of the present invention is to utilize the fact that the solubility of halogen in hexachlorobutadiene differs depending on the temperature for absorption and production of halogen, and the temperature is lowered during halogen absorption and raised during production. By adopting the above configuration, the following effects are produced.

(1) Hexachlorobutadiene has a chlorine solubility curve as shown in Figure 2, and is approximately 0.35 kg/kg at -5℃.
, dissolves about 0.11Kg/chlorine at 25℃. Therefore, for example, by changing the temperature between these times, approximately 0.24 kg of chlorine can be absorbed or supplied with this solvent 1. The melting point of this solvent is −20
℃, the boiling point is 250℃ and about 1 mmHg at 25℃
Since it has such a low vapor pressure, there is no problem with the solvent being taken out when gas is released.

(2) Plastics are often used as structural materials for batteries, but there are only a few plastics that are resistant to corrosion by chlorine gas or aqueous solutions containing chlorine. PVC, acrylic resin, etc. are relatively good except for fluorine-containing plastics, but they are easily attacked by organic solvents.

However, since the butadiene in the molecule of hexachlorobutadiene used in the present invention has a conjugated double bond, the effect of substituted chlorine changes and the effect of dissolving or swelling PVC is very small, which is advantageous.

〔Example〕

Next, the content of the present invention will be specifically explained using Examples, but these are merely examples and do not limit the scope of the present invention.

Example 1 A secondary battery having the configuration shown in FIG. 3 was assembled using chlorine as the positive electrode active material and zinc as the negative electrode active material.

Battery part: 15 single cells each with an effective area of 1100 cm ² made of porous graphite for the positive electrode and dense graphite for the negative electrode are connected in series and output.
The battery can be charged and discharged for approximately 5 hours at 500W.

Electrolyte tank...100 equipped with a liquid circulation port, gas injection port, gas circulation port, and a heat exchanger for liquid temperature adjustment.
A plastic container with a volume of

Chlorine gas storage: A plastic container with a capacity of 50 ml, equipped with a gas inlet, an outlet and a heat exchanger for regulating the liquid temperature.

Cooler: Freon gas compression refrigerator with 200W electric motor.

Gas pump...A bellows type gas pump with a 65W electric motor.

Electrolyte pump: A sealed titanium liquid pump with a 65W electric motor.

Assemble the above equipment and fill the electrolyte tank with 70 2mol
A zinc chloride aqueous solution and 40 hexachlorobutadiene were placed in a chlorine gas storage tank to construct a battery.

First, the hexachlorobutadiene in the gas storage tank
The temperature was raised to 25°C, chlorine gas was blown in from the outside to make the solution sufficiently saturated, and then the solution was cooled to -5°C and charged at 500Kw for 3 hours. Chlorine gas generated during charging was blown into hexachlorobutadiene and absorbed. The heat generated due to absorption was cooled by operating a refrigerator connected to a cooler to maintain the temperature at -5°C.

After charging for 5 hours, the battery was immediately discharged with an output of 450W. Chlorine to be consumed by the positive electrode during discharge was supplied by gradually increasing the temperature of the chlorine gas storage tank, blowing chlorine gas generated into the electrolytic solution, absorbing it into the electrolytic solution, and then flowing the positive electrode together with the electrolytic solution. The discharge lasted for 4 hours and 40 minutes. The temperature of the gas storage tank was gradually increased to reach a final temperature of 25°C. The energy efficiency of the battery was 80%.

Example 2 A primary battery having the configuration shown in FIG. 4 was assembled using chlorine as the positive electrode active material and zinc as the negative electrode active material. The battery consists of 30 cells, with 10 cells connected in series and 10 in parallel, using porous graphite for the positive electrode and rolled zinc plate for the negative electrode. The electrode area in this case is 100cm ²
It was hot. Both terminals were taken out to the outside while the container was sealed. This is 30cm long, 60cm wide, and 50cm high.
stored in a plastic-lined iron container.

The iron container has a gas inlet, an electrolyte inlet, a pressure gauge,
Equipped with pressure relief valve and hydrogen gas reactor. The gas outlet is connected to an iron chlorine gas storage tank with a volume of 3 via a constant pressure valve. 3 kg of hexachlorobutadiene was placed in the chlorine gas storage tank and dissolved at a chlorine pressure of 5 kg/cm ² to dissolve approximately 1 kg of chlorine. An electrolytic solution 50 consisting of an aqueous solution containing 1 mol of zinc chloride and 3 mol of supporting salt was placed in a battery container.
After replacing the space with chlorine gas, it was connected to a chlorine gas storage tank via a constant pressure valve set at 1 kg/cm ² . Discharge of approximately 50W continued for 20 hours. The chlorine in the electrolyte consumed during discharge is supplied from the chlorine storage tank, so the chlorine concentration in the electrolyte is approximately 0.6g/
It was maintained above. It was also possible to perform the discharge intermittently. This primary battery had a capacity of approximately 1 kWh.

Comparative example Using the same device as in Example 1, 50
of water and operated in the same manner. In this case, the water was cooled to 0° C. at the start of charging, and the generated chlorine was blown into the water to form hydrates. During this time, the heat generated by hydrate formation was cooled by running a refrigerator. As in Example 1, the battery was charged at 500W for 3 hours and immediately discharged at 400W output. The chlorine gas required at this time was generated by gradually increasing the temperature of the gas storage tank and decomposing the hydrate. Discharge is 2 hours
It lasted 49 minutes. The final gas storage tank temperature was 9°C. The energy efficiency of the battery was approximately 75%.

The amount of power consumed for operating the auxiliary equipment in this one cycle of operation was 620Wh for the cooler, 1120Wh for the gas pump, and 420Wh for the liquid pump.

In Example 1, compared to the comparative example, the cooler power amount was about 1/4, and the gas pump power was about 1/2.
The gas pump power decreases because hexachlorobutadiene absorbs chlorine well, so the amount of chlorine circulating in the system during charging can be reduced.

〔effect〕

As described above, the battery according to the present invention has higher energy efficiency than conventional batteries, and has extremely significant industrial effects.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the charging/discharging reaction of a zinc-chlorine battery.
Figure 2 shows the solubility of chlorine in hexachlorobutadiene, Figure 3 shows the basic structure of a secondary battery, and Figure 4 shows the basic structure of a primary battery.

Claims (1)

[Claims] 1. A battery having a positive electrode and an aqueous electrolyte containing a halogen as an active material, wherein the halogen is dissolved in hexachlorobutadiene and stored or supplied.