JPH0564433B2 - - 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 becomes chlorine hydrate (ice-like solid) and becomes stable. 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 described 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 ₂ .10H ₂ O.
It is stored as a solid hydrate.

There is also a method of storing it as a complex compound instead of a hydrate, or a method of pressurizing it and making it into a liquid.

[Problems with conventional technology]

When a halogen is made 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 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. The accompanying water or aqueous solution must be cooled or heated each time, resulting in a large energy loss, which reduces the overall 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 obstructing water convection, making it difficult to efficiently absorb a large amount of halogen into water or an aqueous solution. .

[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 in which a halogen is used as an active material, and is characterized in that the halogen is stored or supplied dissolved in a halogen-containing organic solvent other than hexachlorobutadiene.

[Effect]

The key point of the present invention is to utilize the fact that the solubility of halogen in organic solvents 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) Halogens do not form hydrates or complex compounds, so there is almost no heat of hydration or reaction.
Therefore, there is almost no energy loss during storage and supply.

(2) Storage of organic solvents requires cooling a large amount of water or aqueous solution in order to generate hydrates and complex compounds, and heating this large amount of water or aqueous solution in order to decompose it. Although heating and cooling are performed depending on the purpose of use, the specific heat of organic solvents is often around 20% that of water, and therefore the energy loss consumed by raising and lowering the temperature of the solvent is extremely small.

(3) Contrary to the fact that halogen hydrates and complex compounds are generally solid, in this method the halogen is simply dissolved in the organic solvent, and even after absorption, the halogen remains a homogeneous solution, so absorption proceeds efficiently from beginning to end. Not only is the amount of power required for the gas pump reduced, but it is also easier to handle.

(4) By selecting an organic solvent, the range of heating and cooling can be set over a wide range, and a large amount of halogen can be absorbed with a small amount of solvent.

(5) By using an organic solvent that is insoluble in water, water will separate when the halogen containing water is dissolved in the organic solvent, so the halogen will be absorbed in an anhydrous state, and the resulting solution will have extremely low corrosivity. It can be stored in a metal container such as iron. This can be used particularly effectively when used in primary batteries.

The organic solvent used may be any organic solvent as long as it does not react with the halogen and dissolves the halogen, but preferably it has the following properties.

(1) Maintain a stable liquid within the operating temperature range of heating and cooling.

(2) The vapor pressure must not be too high within the operating temperature range.

(3) The temperature dependence of solubility is large.

Specifically, halogenated hydrocarbons, such as carbon tetrachloride, fluorinated hydrocarbons, and fluorinated chlorinated hydrocarbons, exhibit good properties.

When the principle of the present invention is applied to a primary battery or a secondary battery, the basic structure thereof is illustrated in FIG. 2 (primary battery) and FIG. 3 (secondary battery). Of course, batteries utilizing the principles of the present invention may have many structures other than this example, and the structures shown here are only some of them.

Figure 2 shows an example of a primary battery, in which a halogen storage tank 1 contains an organic solvent in which halogen is sufficiently dissolved.
It consists of a battery section 2 consisting of a negative electrode having at least one set of metal active materials, a positive electrode controlling a halogen reaction, and a metal halide solution.

As the discharge progresses, halogen in the electrolyte is consumed and valve V ₁ 3 opens to supply halogen from the halogen storage tank. The halogen storage tank 1 can be heated and cooled by a heat medium flowing through a heat exchanger using a valve, and the halogen pressure in the halogen storage tank is maintained at a constant pressure and released as necessary.

FIG. 3 shows an example of a secondary battery, which consists of a halogen storage tank 1, a battery section 2 having at least one set of negative and positive electrodes, and an electrolyte storage tank 3.

It consists of a gas circulation system with a gas pump P ₁ 4 and a liquid circulation system with a liquid pump P ₃ 5.

During charging, the halogen generated from the battery is introduced into a halogen storage tank kept at a relatively low temperature and absorbed. During discharging, the temperature of the storage tank is gradually raised and the generated halogen is introduced into the electrolyte storage tank, dissolving the halogen in the electrolytic bath. This liquid is circulated and supplied to the battery part by liquid circulation to cause a discharge reaction to occur.

The present invention is a technology that can be used in all batteries that use halogen as the positive electrode active material, and is not limited by the type of active material used in the negative electrode or the structure of the battery.

〔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 section: 30 single cells each with an effective area of 320 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 at 500W for approximately 3 hours.

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

Organic solvent gas storage tank: A plastic container with a capacity of 50 mm, equipped with a gas inlet/outlet and a heat exchanger for controlling the liquid temperature.

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

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

Electrolyte pump...Sealed liquid pump with a 65W electric motor.

In the battery constructed with the above equipment, 2 ml of zinc chloride aqueous solution was used as the electrolyte, and carbon tetrachloride was used as the organic solvent for storing chlorine gas.

First, the carbon tetrachloride in the gas storage tank is heated to 20℃, and chlorine gas is blown in from the outside to saturate it, and then it is heated to 5℃.
The battery was cooled to 500 W and charged for 3 hours. The chlorine gas generated during this time was blown into carbon tetrachloride in the gas storage tank and absorbed. The heat generated by absorption was cooled by operating a heat exchanger connected to a cooler to maintain the liquid temperature at 5°C.

Immediately after 3 hours of charging, the battery was discharged with an output of 400W. Chlorine consumed at the positive electrode was supplied by gradually increasing the temperature of the gas storage tank, blowing the gas generated into the electrolytic solution, absorbing it into the electrolytic solution, and then flowing it together with the electrolytic solution to the positive electrode. The discharge lasted for 2 hours and 48 minutes. The temperature of the gas storage tank eventually reached 25°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 150wh for the cooler, 570wh for the gas pump, and 420wh for the liquid pump.

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 auxiliary equipment operation in this one cycle of operation is 620wh for the cooler and gas pump.
It was 1120wh and the liquid pump was 420wh.

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.

Example 2 1-monochlor, 1', with an average molecular weight of about 700 was used instead of carbon tetrachloride as a solvent for storing chlorine gas.
Charging and discharging were carried out using the same equipment and operating method as in Example 1, except that a 2,2' trifluoroethylene oligomer was used. The energy efficiency of the battery is approximately 73
%, and the power used in this case is the cooling machine
It was 160wh, gas pump 550wh, and liquid pump 415wh.

Example 3 A battery with 10 cells in parallel and 3 cells in series was constructed using porous graphite for the positive electrode and a rolled zinc plate for the negative electrode, each electrode having a single cell of 100 cm ² .
Both terminals were taken out to the outside while the container was sealed. This was stored in a plastic-lined iron container measuring 30 cm in length, 60 cm in width, and 50 cm in height. The iron vessel is equipped with a gas inlet, an electrolyte inlet, a pressure gauge, a pressure safety valve, and a 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 carbon tetrachloride was placed in the chlorine gas storage tank, and chlorine was dissolved at a pressure of 5 kg/cm ² until it was saturated. Approximately 1 kg of chlorine was dissolved. An electrolytic solution 50 containing 1 molar concentration of zinc chloride and 3 molar concentration of supporting salt was placed in a battery container. The constant pressure valve of the chlorine gas storage tank was set at 1 kg/cm ² G, and chlorine gas was introduced through the blowing pipe. Approximately 50W discharge 2
After a certain period of time, the valve to the gas storage tank was closed and the discharge was completed until almost no electromotive force was generated. It was possible to perform such operations intermittently. This primary battery had a capacity of approximately 1kwh.

〔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 basic structure of a primary battery, and Figure 3 shows the basic structure of a secondary battery.

Claims (1)

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