JPS62271373A - Electrolyte circulation type metal-halogen battery - Google Patents

Abstract

PURPOSE:To decrease electrolyte resistance to increase the energy density of a battery by arranging partition plates which divides an electrolyte storage tank between an outlet installed in the upper part of an electrolyte storage tank and an inlet installed in its lower part. CONSTITUTION:Partition plates 42-1, 42-2, and 42-3 are arranged between an inlet 38 and an outlet 40. When a battery is assembled, concentrated electrolyte A and dilute electrolyte B ere filled in the lower part and the upper part of a negative electrode side electrolyte storage tank 36 respectively. In the early stage of charge, the dilute electrolyte B is supplied to a negative reaction cell from the outlet 40. After reaction in the reaction cell, the electrolyte is returned to the lower part of the storage tank 36. The concentrated electrolyte A in the lower part gradually diffuses upward through a passage 44, and the concentration of the electrolyte in the upper part is increased. In the discharge in which decrease in electrolyte concentration cause disadvantage, the dilute electrolyte B is supplied to the anode side reaction cell from the outlet 40 to accelerates the reaction, and after the concentration is increased, the electrolyte is returned from the inlet 38.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrolyte circulating metal-halogen battery, particularly to the internal structure of an electrolyte storage tank.

[Prior Art] As metal-halogen batteries, zinc-bromine secondary batteries and zinc-chlorine secondary batteries are conventionally known. Such secondary batteries obtain practical voltage and current by connecting single cells in series or parallel as necessary.

It is also often used as a bipolar stacked battery.

The principle of the metal-halogen battery will be explained with reference to FIG.

In the figure, in a reaction tank 10, a positive electrode 12 and a negative electrode 14 are partitioned by a separator 16 into a positive electrode chamber 10a and a negative electrode chamber 10b. An electrolyte circulation path is formed between them via piping 22.

The electrolyte flowing through this sprinkling pipe 22 is pumped by a pump 24a,
24b to reaction 1910.

In the reaction tank, during charging, halogen is generated on the positive electrode side, and metal is deposited on the negative electrode side.

Further, during discharge, the metal deposited on the negative electrode plate is oxidized to become metal ions and dissolved in the electrolytic solution, and the halogen in the electrolytic solution is reduced to become halogen ions and dissolved in the electrolytic solution.

As an electrolyte circulating type laminated secondary battery based on this principle, Japanese Patent Laid-Open No. 57-199167 and Japanese Patent Application Laid-open No. 1983-1999
The technique described in Japanese Patent No. 96671 is well known.

That is, FIG. 6 shows an exploded perspective view of a stacked zinc-bromine battery, and in the same figure, the electrode 12 (14) is composed of an insulating part 26 and a conductive part 13, and a manifold is arranged on the diagonal of the electrode 12 (14). 28 are provided. The separator 16 also has a separator frame 30 around the separator membrane 16a, and the separator frame 30 includes a manifold 29 and channels 32 for supplying electrolyte to the positive electrode chamber and the negative electrode.
are formed, and further a channel 32 and a separator film 16a are formed.
A rectifier 334, 34 is provided between the electrolyte and the electrolyte to uniformize the flow of the electrolyte in the reaction tank.

In the above, when the battery is charged, zinc is deposited on the side corresponding to the negative electrode 14 shown in FIG. 5 described above, and bromine is generated on the side corresponding to the positive electrode 12.

[Problems to be solved by the invention] In this case, the factors involved in the electrodeposition of zinc include, for example, the composition of the electrolyte, the pH of the electrolyte, the temperature of the electrolyte, the structure of the electrode If4, and the electrolyte. Many factors have an influence, such as circulation speed, and among these? l! Composition of crude solution The temperature of the halide (zinc bromide or zinc chloride), which is the main material of the battery, has a very large effect on electrodeposition.

As an example, FIG. 7 shows the results of the electrodeposition state investigated using a hill using an aqueous solution of zinc bromide for the positive electrode and a carbon plastic electrode for the negative electrode.

As is clear from the figure, the deposited thickness increases and deteriorates with repeated charging and discharging, but 4M-ZnBr
2 The thickness of the deposited zinc in the aqueous solution was 3M-Z at the time of initial charging.
The result is that the zinc thickness is more than twice that of the nB,2 aqueous solution, and it can be seen that a lower electrolyte concentration is desirable from the standpoint of zinc electrodeposition.

In conventional batteries, when attempting to charge without completely discharging, the state of the zinc deposited on the negative electrode becomes worse than the previous charge, so by repeating charging and discharging, the zinc passes through the separator and forms a dendrite. It precipitates in the positive electrode chamber as resinous crystals). For this reason, a self-discharge reaction with halogen occurs at the positive electrode, which not only causes a decrease in Coulombic efficiency, but also causes deterioration of the separator and deterioration of the Ti pond.

To solve this problem, completely drain the battery before each charge.
It was necessary to turn on the electricity, but each time I did so, I was losing energy.

This invention was made in order to solve this problem, and it is an electrolytic method that improves energy efficiency by sending l-liquid of low specificity to reaction (θ) through charging and discharging. The purpose of the present invention is to provide a liquid circulation type fully bending halogen battery.

[Means and effects for solving the problem] The electrolyte circulating type metal-halogen battery according to the present invention is separated from each other using a separator film for self-discharge prevention, and a predetermined charge/discharge reaction is carried out via the electrolyte. The electrolyte on the positive side and the electrolyte on the negative side are circulated independently between the positive electrode side reaction tank and negative electrode side reaction tank and the electrolyte storage tank arranged corresponding to each reaction tank. At least one electrolyte outlet in the electrolyte storage tank is provided above the inlet, and the electrolyte is disposed between the outlet provided in the upper part and the inlet provided in the lower part. Partition plates are arranged to divide the storage tank.

This partition plate allows the electricity W in the T1wI liquid storage tank to be The liquid will be communicated through the flow path formed between the partition plate and the side wall of the electrolyte storage (a), but there will be a difference in the electrolyte concentration between the upper and lower parts of the storage tank. During charging and discharging, an electrolytic solution with a low concentration of metal halide is sent to the negative electrode side reaction tank, making it possible to lower the electrolytic solution resistance on average and improve the energy efficiency of the battery.

[Example] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a sectional front view of a negative electrode side electrolyte storage tank applied to the battery of the present invention. An electrolyte circulation path is formed via piping between this negative electrode side electrolyte storage tank 36 and a negative electrode side reaction tank (not shown). The negative electrode solution is fed into the negative electrode side electrolyte storage tank 36 from the negative electrode side reaction tank via the inlet 38 by a pump, and from the negative electrode side electrolyte storage tank 4936 is sent to the negative electrode side reaction tank via the outlet 40. Electrolyte is pumped. Since the above configuration is the same as that described above, the explanation thereof will be omitted here.

Here, the characteristic feature of the present invention is that at least one electrolyte outflow port in the electrolyte storage tank is provided above the inflow port, and the outflow port is protected at the top and the outflow port is provided at the bottom. Partition plates are arranged between the inlet and the electrolyte storage tank to divide the electrolyte storage tank, and the electrolyte is communicated through channels formed between the partition plates and the side walls.

In this embodiment, the inlet 38 for the negative electrolyte is provided below the outlet 40, and therefore the negative electrolyte is supplied to the inlet 38 provided at the bottom of the electrolyte storage tank 36.
It flows into the tank and is sent out to the negative electrode side reaction tank from the outlet 40 provided at the top.

That is, partition plates 42-1, 42-2, 42-3 are provided between the inlet 38 and the outlet 40, and these partition plates 42 are connected to the inside of the electrolyte storage tank 36. They are stretched alternately from one side wall to the other side wall, and are attached so that flow paths 44-1, 44-2, and 44-3 are formed between each side wall and the other side wall. The negative electrode electrolyte storage tank 36 is divided into upper and lower halves by the partition plate 42, and the electrolyte is communicated with each other by a flow path 44.

The present invention having the above configuration will be explained in detail.

First, during battery assembly, high concentration liquid A and low concentration liquid B are injected into the lower and upper parts of the negative electrode side electrolyte storage tank 36, respectively. The high-concentration liquid A and the low-concentration liquid B are mixed so as to have a predetermined electrolyte concentration. For this reason,
At the beginning of charging, the low concentration solution B is sent to the negative electrode side reaction tank from the outlet 40, and after the electrolyte undergoes a reaction in the negative electrode side reaction tank, it is returned to the lower part of the electrolyte storage R136 from the inlet 38. It will be done.

On the other hand, since the high-temperature liquid injected into the lower part of the storage tank gradually diffuses to the upper part via the flow path 44, the electrolyte concentration at the upper part of the storage tank increases accordingly, and the electrolyte concentration decreases. It is possible to prevent problems caused by overheating on the battery reaction. Furthermore, at the end of charging, the difference in concentration between the upper and lower parts of the electrolyte storage tank is almost eliminated, and the concentration of the electrolyte sent to the negative electrode side reaction (soda) is made uniform.

In addition, during discharging, low concentration electrolyte B is sent from the upper outlet 40 of the negative electrode side electrolyte storage tank 36 to the negative electrode side reaction tank, promotes the discharge reaction, becomes slightly concentrated, and then enters the inlet. 38 to the lower part of the electrolyte. By repeating this, there is a large concentration difference between the upper and lower parts of the storage tank in the early hours of discharge, which becomes almost the same as the state at the beginning of charging.

A second embodiment of the invention is shown in FIG.

In this embodiment, the number of partition plates 142-L...142-6 is further increased to zero inside the negative electrode side electrolyte storage tank 136, and the electrolyte storage tank 136 is divided into three rooms
This makes it possible to more effectively maintain the difference in the concentration of the electrolytic solution between the upper and lower parts of the storage tank 136 during discharge, and to diffuse it in stages.

FIG. 3 shows a third embodiment of the invention. This °
In this embodiment, in addition to the electrolyte outlet 240 at the upper part of the electrolyte storage tank 236, another outlet 242 is provided at the lower part, and both of these outlets 24Q.

The conduits 48 drawn out from 242 are merged into one place,
It is connected to piping 52 via a valve 50. The valve 50 is normally set so that the upper outlet 240 and the pipe 52 are connected, but at the end of charging, it becomes difficult for the lower electrolyte in the electrolyte storage tank 236 to diffuse to the upper part. In this case, the valve 50 is switched to simultaneously send the upper electrolyte and the lower electrolyte from the electrolyte storage tank 236 to the negative electrode side reaction tank, thereby making effective use of the electrolyte during charging.

As explained above, according to this embodiment, for example, the electrolyte is 4.0 mol/! When using a zinc bromide aqueous solution of
．． 2m01/I, and if the present invention is not applied (4
~1.2 mol/l), it becomes possible to effectively reduce the electrolyte resistance.

Furthermore, since a negative electrode liquid having a low specific gravity on average is sent to the negative electrode side reaction tank through charging and discharging, a small pump output is sufficient, and the net energy efficiency of the battery can be improved.

Furthermore, since the state of zinc electrodeposition is affected by the concentration of zinc halide, by applying the present invention, when the maximum degree of electrolyte sent into the stack is set to the same concentration as that of conventional batteries, the average It becomes possible to increase the set concentration of zinc halide (charging surface concentration), and it is possible to reduce the amount of electrolyte, that is, to improve the energy density.

[Effects of the Invention] As explained above, in this invention, a partition plate is arranged to divide the electrolyte storage tank between the outflow port provided at the top and the inflow port provided at the bottom of the electrolyte storage tank. This makes it possible to feed an electrolytic solution with a low concentration of halide on average into the reaction tank through charging and discharging, thereby lowering the electrolytic solution resistance and improving the energy efficiency of the battery.

[Brief explanation of the drawing]

FIG. 1 is a sectional front view of a negative electrode side electrolyte storage tank applied to a circulating electrolyte type metal-halogen battery according to the present invention, and FIGS. 2 and 3 are respectively showing other embodiments of the negative electrode side electrolyte solution. Figure 4 is a diagram showing the relationship between zinc bromide temperature and electrolyte resistance. Figure 5 is a diagram explaining the principle of a metal-halogen battery with electrolyte circulation. Figure 6 is a stacked zinc battery. - An exploded perspective view of a bromine battery, FIG. 7 is a diagram showing changes in the state of electrodeposition when a bromide aqueous solution is used, zinc is used as the positive electrode, and a carbon plastic electrode is used as the negative electrode. 36.136.236 ... Negative electrode side electrolyte storage tank 38 ... Inflow port 40.240.242 ... Outflow port 42 ...
Partition plate 44... Channel

Claims (1)

[Claims] A positive electrode side reaction tank and a negative electrode side reaction tank that are separated from each other using a separator film for self-discharge prevention and perform predetermined charging and discharging reactions via an electrolyte, and an electrolyte storage tank arranged corresponding to each reaction tank. In an electrolyte circulation type metal-halogen battery in which a positive electrode side electrolyte and a negative electrode side electrolyte are each independently circulated between At the same time, a partition plate is arranged to divide the electrolyte storage tank between an outlet provided at the top and an inlet provided at the bottom, and the electrolyte flows between the partition plate and the side wall. 1. An electrolyte circulation type metal-halogen battery, characterized in that the electrolyte circulation type metal-halogen battery is connected to each other by a flow path formed between the two.