JPS6380486A - Circulating electrolyte type metal-halogen battery - Google Patents

Abstract

PURPOSE:To prevent a self-discharge during a battery is left unused and to improve battery efficiency by changing an electrolyte in a reaction chamber by means of a pump driven automatically when the temperature inside the reaction chamber rises beyond a specified value during the battery is left unused. CONSTITUTION:When a temperature inside a reaction chamber rises with the progress of self-discharge, the temperature detected by a temperature sensor 52 is compared with a preliminarily determined higher reference value, e.g. 40 deg.C, with the use of a hysteresis comparator 60. If the detected temperature is lower than the higher reference value, a pump 48 is kept being stopped. But, if the detected temperature is higher than the higher reference value, an 'on'-signal is outputted to a pump driver 53 and the pump 48 is driven. By the arrangement, an electrolyte is circulated between the reaction chamber 44 and an electrolyte storage chamber 46, and the electrolyte inside the reaction chamber 44 is exchanged.

Description

[Detailed Description of the Invention] [Industrial Application Field J] The present invention relates to a metal-halogen battery with a circulating electrolyte solution, in particular, a battery that circulates an electrolyte between an electrolyte storage tank and a reaction tank to achieve a predetermined charge/discharge reaction. This invention relates to IL and IJ control circuits for batteries of this type.

[Prior Art] Metal-halogen batteries, in which electrolyte is circulated between an electrolyte storage tank and a reaction tank to carry out predetermined charging and discharging reactions, are cheap, reactants are difficult to obtain, and the cell voltage is low. It is of particular interest because the electrode reaction is highly reversible. For example, a conventional zinc-bromine battery is known as one of the new types of batteries, and the basic electrochemical reaction shown in the following equation is performed in a reaction tank provided with a positive electrode and a negative electrode.

(Positive electrode> 2Br −;:Br2+ 2e− (negative electrode)
Zn 2"+2e-;:Zn ・(1) Charging (body) Zn"+23r -;zn +-3r2t
J! 1ffi As is clear from this reaction formula, during charging, zinc 7n is deposited on the negative electrode, bromine Br2 is produced at the positive electrode, and this 3r2 is dissolved in the electrolyte. Also, during discharge, zinc Zn deposited on the negative electrode plate is oxidized to become Zn''t= and dissolved in the electrolyte, and bromine Br2$,
is reduced to become bromine ion 2Br-, which is similarly dissolved in the electrolyte.

By the way, in such a zinc-bromine battery, the concentration of the odor 1iBr2 in the electrolyte solution generated during charging increases as the charging time increases, and the Q element Br2 gradually diffuses to the negative electrode side. Then, the bromine [3r2 reacts with zinc 7-n on the negative electrode side and becomes zinc ion Zn2+ and bromine ion 3r-, causing self-discharge. Therefore, this zinc-bromine battery has no lead ion Using a separator membrane for self-discharge prevention that transmits Zn2+ and bromine ions Br- and blocks AyA of Q element B, the reaction tank is separated into a positive electrode side reaction tank and a negative electrode side reaction tank. Bromine 3 to the side
This prevents the diffusion of r2.

Furthermore, in the zinc-bromine battery, in order to prevent the diffusion of bromine 3r2, a complexing agent is added to the electrolyte, and the bromine Br2 dissolved in the positive electrode side electrolyte is converted into a complex compound that is difficult to dissolve in the electrolyte. It is separated and precipitated as an oil in the electrolyte.

FIG. 5 shows a conventional zinc-bromine battery formed using such a principle (Japanese Patent Application Laid-Open No. 52-1228).
35. JP 57-199167, U.S. Patent No. 4,105
．． 829), in the same figure, inside the reaction tank 10, the positive electrode 12
Both negative electrodes 14 are partitioned by a separator film 20 into a positive electrode chamber 10a and a negative electrode chamber 10b, and pipes 26, 28 and 38. An electrolyte circulation path is formed through 40, and the electrochemical reaction of the first type is performed. And it flows through pipes 26.28 and 38.40? [1
is pumped into the reaction vessel 10 by pumps 30, 42.

like this! [[i] In the lead-bromine battery, a zinc bromide (ZnBr2) aqueous solution is used as the electrolyte 16, and in addition to this, a conductivity improver such as KCl or N)-14G1'8 may be added as necessary. A complexing agent that reacts with bromine to form a complex compound that is insoluble in the electrolyte and has a higher specific gravity than the electrolyte;
For example, bromine complexing agents such as quaternary ammonium salts (mebruethyl mole small linium bromide, methylethylpyrrolidinium bromide), dendrite inhibitors, etc. are added.

Then, during charging, a charging reaction shown in the first equation described in 1.
2 is generated and dissolved in the electrolytic solution 16, and zinc zn is precipitated on the negative electrode 14 side, forming a zinc deposit layer 18 on the negative electrode 14.

Also, fi? At the time of ff, a reaction opposite to that at the time of charging takes place, and on the positive electrode 12 side, bromine [3r2 is reduced and becomes bromine ion 2Br-, which is dissolved in the electrolytic solution 16, and the negative electrode 14
On the side, the zinc precipitate layer 18 is oxidized to form zinc ions Zn2.
+1! : and dissolves in the electrolyte 16.

The inside of the reaction tank 10 where such an electrochemical reaction is carried out is separated by a separator film 20 into a positive electrode side reaction tank 10a and a negative electrode side reaction tank 10b so that self-discharge does not occur due to bromine Br2 generated during charging. It is separated into

This separator film 20 allows the electrolytic solution 16 to pass therethrough in order to prevent self-discharge, but prevents the Q-cumulative Qr2 dissolved therein from passing through. Such a separator film 2
As 0, it is generally an ion exchange! ! ! ! A membrane or a porous membrane can be used, and from the viewpoint of reducing the internal resistance of the battery, it is preferable to use a porous membrane.

Here, if a bromine complexing agent is added to the electrolytic solution 16, the bromine generated during charging [3r2 is 811
In the battery shown in FIG. and stored. In addition, this complex storage section 3
2 and the pipe 28 are communicated by a complex supply duct 36 having a valve 34. This valve 34 is normally open and does not send out the complex compound precipitated in the complex storage section 32 toward the reaction tank 10a via the pipe 28 for discharge.

Further, the negative electrode side electrolyte storage 4e24 similarly forms an electrolyte V1 ring path with the negative electrode side reaction Wi 10b via piping 38.40, and uses a pump 42 provided in the circulation path. The negative electrode electrolyte that has reacted in the negative electrode reaction tank 10b is sent out to the storage tank 24, and a new electrolyte is supplied from the storage tank 24 to the reaction tank 10b.

In this way, this zinc-bromine battery has an electrolyte storage tank 22.
．． A sufficient amount of electrolyte 16 is stored in the battery 24, and when charging using the stored electrolyte 16, the charging reaction shown in the first formula is carried out, and a complex compound of bromine is stored in the complex storage 'atB32.
A zinc precipitate layer 18 may be formed on the negative electrode 14 to store power. Also, during discharge, the bromine complex compound stored in the complex storage Q section 32 is transferred to the positive electrode side reaction tank 10a.
The complex compound and the zinc deposited layer 18 formed on the negative electrode 14 are used to carry out the discharge reaction shown in the first equation, and the charging power can be released.

In the above, conventionally, while the zinc odor Xm battery was charged and left unattended, the positive and negative electrode pumps 30 and 42 were stopped and the electrolyte remained stationary.

[Problems to be Solved by the Invention] Conventional Problems However, when a metal-halogen battery as described above is left without being completely discharged, the following problems occur.

■ Heat is generated as the halogen held in the positive reaction tank and the metal electrodeposited on the electrode plate of the negative reaction tank cause self-discharge, and this heat is transferred to the components of the reaction tank. is generally made of plastic or the like and has difficulty dissipating heat, so it accumulates inside the reaction tank. At this time, as shown in FIG. 4, the discharge rate increases as the temperature inside the reaction tank increases, resulting in a decrease in battery capacity.

■Also, as the temperature inside the reaction tank further rises due to self-discharge, while halogen remains in the positive electrode side reaction tank, the battery capacity decreases even more, and the energy efficiency of the battery decreases. will occur.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems.The present invention detects the temperature inside the reaction tank while the battery is left unused, and measures the a2 temperature at this time.
When the temperature exceeds a predetermined value, the pump is automatically driven to replace the electrolyte in the reaction tank, preventing self-discharge and improving battery efficiency. The purpose is to provide batteries.

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides a method in which a reaction tank formed between an electrode plate and a separator is connected to the positive electrode side of each other by a separator film for preventing self-discharge. An electrolyte circulation type that has a partition on the negative electrode side and circulates the positive electrode electrolyte and negative electrode electrolyte between the electrolyte storage tank and the reaction tank using a liquid circulation pump and conducts charge/discharge reactions via these electrolytes. In a metal-halogen battery, a temperature detection unit detects the temperature inside the reaction tank, a pump drive unit drives a liquid circulation pump, and a temperature detection unit that detects the temperature inside the reaction tank compares the detected temperature with a preset reference value. The present invention is characterized in that it includes a comparison operator that outputs an ON signal to the pump drive unit when the temperature of the battery is equal to or higher than a reference value, thereby reducing self-discharge ω while the battery is left unused.

Generally, in a reaction tank, when the halogen held in the positive electrode side reaction tank and the metal electrodeposited on the negative electrode plate self-discharge through the separator film, heat is generated and the temperature inside the reaction tank rises. do. The 4 degree detection section detects the temperature inside the reaction tank, and the detected temperature t at the time of cooking is compared with a preset reference value in the comparison calculation section. When the detected temperature is higher than U*hn, it is determined that self-discharge is progressing in the reaction tank, and an ON signal is output from the comparison calculation section to the pump drive section, the pump is driven, and the electrolytic solution is An electrolytic solution is circulated from the storage tank to the reaction tank.

As a result, the electrolytic solution in the reaction tank is replaced, the self-discharge rate is reduced, and the battery efficiency is improved.

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

FIG. 1 shows a system block diagram of a metal-halogen battery with circulating electrolyte according to the present invention.

In the figure, an electrolytic solution is circulated between a reaction tank 44 and an electrolytic solution storage tank 46 via a pipe 50 by a pump 48,
A predetermined charging/discharging reaction is performed in the reaction tank 44 via this electrolytic solution.

Here, the characteristics of the present invention include a temperature detection section that detects the temperature inside the reaction tank, a pump drive section that drives the liquid circulation pump, and a temperature detection section that detects the temperature inside the reaction tank, a pump drive section that drives the liquid circulation pump, and a reference value that is set in advance to match the detected temperature. and a comparison vJ calculation section that compares the temperature of the reaction tank with the temperature of the reaction tank and outputs an ON signal to the pump drive section when the temperature inside the reaction tank is equal to or higher than a reference value.

That is, in this embodiment, a temperature sensor 52 such as a thermistor is used as a temperature detection section, and its vertical position is at the lower part of the electrode device 33 where the temperature rises the most in the reaction tank, for example, at the end block. It is placed at the bottom of the boundary with the current collector. The pump drive unit 53 includes a relay driver 54, a relay 56, and a pump T1 source 58, and uses a hysteresis comparator 60 as a comparison calculation unit that can set upper and lower reference values.

The pump 48 is not operated and stopped while the battery is left alone, but as the temperature inside the reaction tank 44 increases as self-discharge progresses, this temperature is detected by the temperature sensor 52.
The temperature thus detected is determined by the hysteresis comparator 6.
A predetermined upper reference value at 0, for example 40°
It is compared with C. At this time, when the detected temperature is lower than the upper reference value, the pump 48 is maintained in a stopped state, but when it is higher than the upper reference value, the pump drive unit 5
3, an on signal is output.

This ON signal excites the coil 56a of the relay 56 via the relay driver 54, and the contact 56b is engaged to drive the pump 48 with the power of the pump ff1158. Therefore, the electrolyte is circulated between the reaction 1f 144 and the electrolyte storage tank 46, and the electrolyte in the reaction 4!44 is exchanged. This electrolyte circulation reduces the self-discharge rate, and reaction 4
f! 44 becomes lower than the lower 1m value set by the hysteresis comparator 60, for example 35@C, the hysteresis comparator 60 causes the pump drive unit 5 to
3, an off signal is output to relay contact 56b, and driving of pump 48 is stopped.

In the above, when liquid exchange is performed, for example, reaction tank 4
It is known that when the temperature inside the reactor increases from 40°C to 30°C, the self-discharge rate within the reactor decreases by approximately 30%.

Note that the temperature inside the electrolyte storage tank 46 decreases by 1 degree after one liquid exchange, but it is air cooled by the next liquid exchange, and the same effect as the first can be obtained in the second and subsequent liquid exchanges. It will be.

FIG. 2 shows system blocks in another embodiment.

In this embodiment, the comparison opening section (60) and the pump drive section 5
3, a monostable multivibrator 62 is provided between the two.

As shown in FIG. 3, when the temperature inside the reaction tank 44 exceeds the reference value, the hysteresis comparator 60 outputs an ON signal. Predetermined part 1 set in advance regardless of once? ! A pump-on signal of 1T is output to the pump drive section a 53. The set time T at this time is appropriately determined depending on the circulation speed of the electrolytic solution.

As explained above, according to the embodiments of the present invention, by lowering the temperature inside the reaction tank by performing liquid exchange, the corrosion rate of battery components due to halogen in the electrolyte is reduced, and battery performance is reduced. It is possible to prevent deterioration such as non-uniform electrolyte flow due to electrode swelling, poor electrodeposition, and a decrease in Coulombic efficiency. In addition, when an adhesive such as hot melt is used for battery assembly, lowering the upper limit temperature of the reaction tank can prevent the adhesive from softening and flowing into channels, etc. It becomes possible to maintain battery performance for a longer period of time.

[Effects of the Invention] As explained above, the present invention has a temperature detection section that detects the temperature inside the reaction tank, a pump drive section that drives the liquid circulation pump, and a pump drive section that detects the temperature inside the reaction tank when the temperature inside the reaction tank rises. By being equipped with a comparison operator that outputs an on signal,
It is possible to improve battery efficiency while preventing self-discharge.

[Brief explanation of the drawing]

Fig. 1 is a system block diagram of a metal-halogen battery with circulating electrolyte according to the present invention, Fig. 2 is a system block diagram showing another embodiment, Fig. 3 is an explanatory diagram of the operation of Fig. 2, and Fig. 4 Figure 5 shows the relationship between electrolyte temperature and self-discharge rate. Figure 5 is the basis of a metal-halogen battery with electrolyte circulation! ! [!
It is an explanatory diagram. 44... Reaction tank 46... Electrolyte storage tank 48... Liquid circulation pump 52... Temperature sensor 53... Pump drive section 54... Relay driver 56... Relay 58... Pump power supply 60 ... Hysteresis comparator 62 ...
Monostable multivibrator.

Claims (3)

[Claims] (1) The reaction tank formed between the electrode plate and the separator is partitioned into a positive electrode side and a negative electrode side by a separator film for self-discharge prevention, and a liquid circulation pump is used to separate the reaction tank between the electrolyte storage tank and the reaction tank. In an electrolyte circulation type metal-halogen battery that circulates a positive electrode electrolyte and a negative electrode electrolyte and performs a predetermined charging/discharging reaction via these electrolytes, a temperature detection unit that detects the temperature in a reaction tank; A pump drive unit that drives a liquid circulation pump compares the detected temperature with a preset reference value, and outputs an ON signal to the pump drive unit when the temperature inside the reaction tank is equal to or higher than the reference value. An electrolyte circulating type metal device, characterized in that it is equipped with a comparison calculation section to reduce the amount of self-discharge when the battery is left unused.
halogen battery. (2) The battery according to claim (1), characterized in that the comparison calculation section outputs an on signal to the pump drive section and then outputs an off signal after a certain period of time has elapsed. -Halogen batteries. (3) The battery according to claim (1), characterized in that the comparison calculation section outputs an off signal when the temperature inside the reaction tank falls below a reference value. halogen battery.