JP2976587B2 - Method for measuring bromine adsorption amount in positive electrode active layer of zinc-bromine battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the amount of bromine adsorbed on a positive electrode active layer of a zinc-bromine battery.

[0002]

2. Description of the Related Art A zinc-bromine battery is a simple battery composed of zinc bromide and a pair of electrodes. At the time of charging, zinc is deposited on the negative electrode, and at the positive electrode, the generated bromine is dissolved in the electrolytic solution. During discharge, zinc on the negative electrode is oxidized and zinc ions (Zn
⁺⁺ ), dissolves, and the bromine is reduced to a bromine ion (Br).
^- ). The reaction equation is shown as the following equation.

During charging: positive electrode: 2Br ⁻ → Br ₂ + 2e ⁻ , negative electrode: Zn ⁺⁺ + 2e ⁻ → Zn During discharging: positive electrode: 2Br ⁻ ← Br ₂ + 2e ⁻ , negative electrode: Zn ⁺⁺ + 2e ⁻ ← Zn When the concentration of bromine generated during charging rises, the battery diffuses on the negative electrode, dissolves zinc, returns to zinc ions and bromine ions, generates self-discharge, and lowers battery efficiency. To prevent this, in actual batteries, pumps and tanks are provided to circulate the electrolytic solution, and bromine is combined with the bromine complex compound added to the electrolytic solution and stored in the tank as a bromine complex compound insoluble in the electrolytic solution. ing.

[0004]

In a conventional zinc-bromine battery, activated carbon fibers are thermocompression-bonded to one side of a carbon plastic electrode (CP). Used as a negative electrode and as a bipolar electrode. Activated carbon fibers are press-bonded to increase the reaction area when bromine is generated. However, if the amount of embedded carbon-carbon press-bonded surface (hereinafter referred to as active layer) in carbon plastic is small, it is generated by charging. Bromine adheres to the active layer and cannot be pumped into the tank by liquid circulation by a pump, and reacts with metal zinc of the negative electrode to cause self-discharge, which causes heat generation. For this reason, the amount of bromine adsorbed on the active layer must be controlled to the minimum necessary during electrode production. That is, it is necessary to measure the amount of bromine adsorbed on the active layer at the time of production.

The present invention has been made in view of the above points, and an object of the present invention is to find bromine adsorption on a positive electrode active layer of a zinc-bromine battery capable of finding conditions for manufacturing a carbon plastic electrode with a positive electrode active layer having good battery efficiency. An object of the present invention is to provide a method for measuring a quantity.

[0006]

According to the present invention, there is provided a method for manufacturing a liquid crystal display comprising:
50-100 ml of an aqueous solution consisting of 5 mol / l ZnBr ₂ and 1.0 mol / l bromine complex, 2 cm ×
2cm square carbon plastic electrode with active layer, 3 ~
A first shaking process of placing 5 ml of bromine in the same flask and shaking them on a shaker for 50 hours;
After the shaking process, a second shaking process in which the carbon plastic electrode is shaken in 100 ml of pure water for 1-2 minutes, and after the second shaking process, the carbon plastic electrode is replaced with 3-6 mol / l ZnBr. ₍₂₎ a third shaking process of shaking in 20 to 50 ml of an aqueous solution for 20 hours. After the third shaking process, the carbon plastic electrode is subjected to an iodine starch reaction with an aqueous solution of sodium thiosulfate to perform chemical titration. Features.

[0007]

The carbon plastic electrode with an active layer is shaken for 50 hours in a mixture of ZnBr ₂ , a bromine complex, and bromine in a first shaking process, and then for 20 hours in an aqueous solution of ZnBr ₂ in a third shaking process. Shaken. For this reason, when the carbon plastic electrode is thereafter examined for an iodine-starch reaction with an aqueous solution of sodium thiosulfate, the color changes to bluish purple or the like. Since the degree of discoloration corresponds to the amount of bromine adsorbed on the active layer of the carbon plastic electrode, the amount of bromine adsorbed can be easily measured from the degree of discoloration. As a result, it is possible to find the production conditions (bromine adsorption 2.0 to 2.2 mAh / cm ² ) of the carbon plastic electrode with a positive electrode active layer having good battery efficiency.

[0008]

An embodiment of the present invention will be described below. Zinc-
The minimum required amount of bromine adsorbed on the active layer in the bromine battery is 2.0 to 2.2 mAh / cm ² . Therefore, when the bromine adsorption amount is at least in the range of 2.0 to 2.2 mAh / cm ² , the battery operates efficiently. First, 1.0-1.5
50-100 ml of an aqueous solution consisting of mol / l ZnBr ₂ and 1.0 mol / l bromine complex, 2 cm × 2
A carbon plastic electrode with an active layer having a cm square is placed in a stoppered Erlenmeyer flask, 3-5 ml of bromine is added, and the mixture is shaken with a shaker for 50 hours. Thereafter, the carbon plastic electrode with the active layer is taken out, washed lightly with water, put into a stoppered Erlenmeyer flask containing 100 ml of pure water, and shaken for 1 to 2 minutes. Thereafter, the electrode is taken out, put into a 3 to 6 mol / l ZnBr ₂ aqueous solution (20 to 50 ml), and shaken for 20 hours. Thereafter, chemical titration is performed using an iodine starch reaction with an aqueous solution of sodium thiosulfate.

As described above, the carbon plastic electrode with an active layer is shaken in a mixture of ZnBr ₂ , a bromine complex, and bromine in a first shaking process for 50 hours, and then in a third shaking process in an aqueous solution of ZnBr _2. For 20 hours. For this reason, when the carbon plastic electrode is thereafter examined for an iodine-starch reaction with an aqueous solution of sodium thiosulfate, the color changes to bluish purple or the like. Since the degree of discoloration corresponds to the amount of bromine adsorbed on the active layer of the carbon plastic electrode, the amount of bromine adsorbed can be easily measured. As a result, it is possible to find out the conditions for producing a carbon plastic electrode with a positive electrode active layer having good battery efficiency.

[0010]

As described above, according to the present invention, after performing the first to third shaking processes, the test electrode is subjected to a chemical titration using an aqueous solution of sodium thiosulfate using an iodine starch reaction. Accordingly, the amount of bromine adsorbed on the electrode active layer can be measured, whereby it is possible to easily find the production conditions of the carbon plastic electrode with a positive electrode active layer having good battery efficiency.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 31/00 G01N 31/16 H01M 4/96 H01M 12/08

Claims (1)

(57) [Claims] 1. A ZnBr _{2 of} 1.0 to 1.5 mol / l.
And an aqueous solution 5 consisting of 1.0 mol / l bromine complex
First, 0 to 100 ml, a 2 cm × 2 cm square carbon plastic electrode with an active layer, and 3 to 5 ml of bromine are placed in the same flask, and they are shaken with a shaker for 50 hours.
After performing the shaking process and the first shaking process, the carbon plastic electrode is placed in 100 ml of pure water for 1 to 1 minute.
A second shaking process of shaking for 2 minutes, and after performing the second shaking process, the carbon plastic electrode is
20 mol / l of ZnBr ₂ aqueous solution in 20 to 50 ml.
And a third shaking process for shaking for a time. A method for measuring the bromine adsorption amount of the positive electrode active layer.