JPS63239782A - Electrolyte circulation type metal-halogen cell - Google Patents

Abstract

PURPOSE:To improve the cell efficiency by detecting the discharge amount of a cell and driving a pump when the detected discharge amount exceeds a standard discharge amount. CONSTITUTION:A discharge detector 52 detects the total sum of the discharge electric amount to the outside and the self-discharge electric amount in a cell discharge condition, and when the total discharge amount at the time exceeds a standard discharge amount, it is detected at a comparison arithmetic unit 53, the ON signal is output to a pump 48 to drive a liquid circulation pump 48, and the circulation of the electrolyte is started. By operating the pump 48 intermittently in such a way, the self-discharge quantity can be reduced, the generation of heat is also reduced, and the cell efficiency can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a metal-halogen battery with a circulating electrolyte solution, in particular, to circulate an electrolyte solution between an electrolyte storage tank and a reaction tank to perform a predetermined lightning discharge reaction. This invention relates to a control circuit for a type of battery.

[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 inexpensive, easy to handle, and have a high cell voltage. , and are 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) 2Br22Br2+2e- (Negative electrode) Zn ''+2e-;l::Zn
-(1) Charging (overall) Zn 2"+2 Br-;: Zn +B
r2 discharge As is clear from this reaction equation, during charging, zinc Zn is deposited on the negative electrode, bromine Br2 is produced at the positive electrode, and this Br2 is dissolved in the electrolytic solution. Also, during discharge, zinc Zn deposited on the negative electrode plate is oxidized and becomes Zn2+ (!:
Bromine Br2 in the electrolyte 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 bromine Br2 generated during charging in the electrolytic solution increases with the passage of charging time, and the bromine Br2 gradually diffuses toward the negative electrode side. Then, the bromine Br2 reacts with zinc Zn on the negative electrode side to become zinc ions Zn''& bromine ions Br-, causing self-discharge. The reaction tank is separated into a positive electrode side reaction tank and a negative electrode side reaction tank using a separator membrane for self-discharge prevention that allows ion Br- to pass through and bromine Br2 to pass through, and bromine Br2 is transferred from the positive electrode side to the negative electrode side. Preventing spread.

Furthermore, in the zinc-bromine battery, in order to prevent the diffusion of the bromine Br2, 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. 4 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
and the negative electrode 14 are separated by a separator film 20 as a positive electrode chamber 10a and a negative electrode chamber 10b, and piping 26, 28 and 38 are connected between the reaction tank 10, the positive electrode side electrolyte storage tank 22, and the negative electrode side electrolyte storage tank 24. An electrolyte circulation path is formed through the .40, and the electrochemical reaction of the first formula is performed. Then, the electrolytic solution flowing through the pipes 26, 28, 38, 40 is pumped to the reaction tank 10 by the pump 30, 42.

In such a zinc-bromine battery, a zinc bromide (ZnBr2) aqueous solution is used as the electrolyte 16, and in addition to this, a conductivity improvement agent such as KCI or NH4Cl may be added as necessary, or a zinc bromide (ZnBr2) aqueous solution may be added as required. Complexing agents that form complex compounds that are insoluble in the electrolyte and have a higher specific gravity than the electrolyte, such as bromine complexing agents such as quaternary ammonium salts (methylethylsoriphorinium bromide, methylethylpyrrolidinium bromide), dendrite suppression agents, etc. are added.

During charging, the charging reaction shown in the first equation is performed in the reaction tank 10, and bromine Br2 is generated on the positive electrode 12 side and dissolved in the electrolytic solution 16, and zinc Zn is precipitated on the negative electrode 14 side. A zinc precipitation layer 18 is gradually formed on the negative electrode 14.

Furthermore, during discharging, a reaction opposite to that during charging occurs,
On the positive electrode 12 side, bromine Br2 is reduced to bromine ions 2B
r- and dissolves in the electrolyte 16, and the zinc deposit layer 18 on the negative electrode 14 side is oxidized to form zinc ions zn2+,! :
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 blocks the penetration of bromine Br2 dissolved therein. Such a separator film 2
Generally, an ion exchange membrane or a porous membrane is used as the membrane, but 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 Br2 generated during charging is complexed and precipitated as a complex compound insoluble in the electrolytic solution 16, as shown in FIG. In the illustrated battery, the complex compound is stored at the bottom of the positive electrode side electrolyte storage tank 22 as a complex storage section 32, where it is sequentially precipitated. Further, a complex supply duct 3 having a valve 34 is connected between the complex storage section 32 and the pipe 28.
It is communicated by 6. This valve 34 is normally open and sends out the complex compound precipitated in the complex reservoir 32 through the pipe 28 toward the reaction tank 10a for discharge.

Further, the negative electrode side electrolyte storage tank 24 similarly forms an electrolyte circulation path with the negative electrode side reaction tank 10b via piping 38, 40, and a pump 4 provided in the circulation path.
2, the negative electrode electrolyte reacted in the negative electrode reaction tank 10b is sent 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 24, and the stored electrolyte 1
When charging using the negative electrode 1, the charging reaction shown in the first formula is carried out, the complex compound of bromine is stored in the complex storage section 32, and the negative electrode 1 is charged.
A zinc deposit 18 can be formed on the 4 to store power. Furthermore, during discharging, the bromine complex compound stored in the complex storage section 32 is sent out to the positive electrode side reaction tank 10a, and the complex compound and the zinc precipitation layer 18 formed on the negative electrode 14 are used. The discharge reaction shown in the first equation can be performed and the charging power can be released.

[Problems to be Solved by the Invention] Conventional Problems However, in conventional zinc-bromine batteries, for example, in those with an electrode area of 6,000 or more, 100
Since the electrolyte is circulated at a flow rate of ml/akin or more, if the electrolyte pump is operated continuously, the energy consumed by the pump becomes extremely large. and,
It is known that when charging and discharging is performed at the usual current density of 2 (1 m^/C-), the energy efficiency of the battery decreases by about 10%.

One possible way to prevent this is to reduce the flow rate of the electrolytic solution, but there is a problem in that reducing the flow rate makes it difficult for the electrolytic solution to flow uniformly over the electrode surface.

Purpose of the Invention The present invention was made to solve the above problems, and detects the discharge amount of the battery and drives the pump when the discharge amount exceeds the standard discharge amount. Electrolyte circulation type that can improve battery efficiency by driving the pump when either of the following conditions is satisfied: when the voltage falls below the standard voltage or when the battery discharge amount exceeds the standard discharge amount. The purpose is to provide a metal-halogen battery.

[Means and Effects for Solving the Problems] In order to achieve the above object, the present invention provides a method in which the reaction layer formed between the electrode plate and the separator is separated from the positive electrode side by a separator film for self-discharge prevention. An electrolytic solution that is partitioned on the negative electrode side and circulates the positive electrode electrolyte and the negative electrode electrolyte between the electrolytic solution storage tank and the reaction tank using a liquid circulation pump, and performs a predetermined charging/discharging reaction via these electrolytes. In a circulating metal halogen battery, there is a discharge detection unit that detects the total discharge amount including the self-discharge amount of the battery, and a comparison calculation that compares the detected total discharge amount with a preset reference discharge amount. and a pump drive unit that drives a liquid circulation pump based on a command from the comparison calculation unit.

That is, the discharge detection section detects the sum of the amount of electricity discharged to the outside and the amount of self-discharged electricity when the battery is discharged, and when the total amount of discharge at this time becomes larger than the reference amount of discharge, it performs a comparison calculation. The electrolyte is detected by the pump drive unit and outputs an on signal to the pump drive unit to start circulating the electrolyte.

Further, in another invention, a reaction tank formed between an electrode plate and a separator is partitioned into a positive electrode side and a negative electrode side by a separator film for self-discharge prevention, and the electrolytic solution is separated by a liquid circulation pump. Battery voltage is detected in electrolyte circulation metal-halogen batteries in which positive and negative electrolytes are circulated between a storage tank and a reaction tank, respectively, and predetermined charging and discharging reactions occur via these electrolytes. a discharge detection unit that detects the total discharge amount including the self-discharge amount of the battery; a first comparison calculation unit that compares the detected voltage with a preset reference voltage; A second comparison calculation unit that compares the total discharge amount and a preset reference discharge amount, and a pump drive unit that drives the liquid circulation pump according to commands from each comparison calculation unit. Features.

Then, when the discharge voltage of the battery becomes lower than the reference voltage,
Or, when the total discharge amount of the battery exceeds the reference discharge amount, or when any one of the following conditions is satisfied, an on signal is output from the comparison calculation section to the pump drive section, and circulation of the electrolyte solution is started.

As described above, the pump can be operated intermittently to improve battery efficiency.

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

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

In the figure, to explain a zinc-bromine battery as an example of a metal-halogen battery, a reaction tank 44 and an electrolyte storage tank 4
An electrolytic solution is circulated between the reactor 6 and the reactor 44 via a pipe 50 by a pump 48, and 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 discharge detection section that detects the total discharge amount including the self-discharge amount of the battery, and a comparison operation that compares the detected total discharge amount with a preset reference discharge amount. and a pump drive for driving a liquid circulation pump according to a command from the comparison calculation section, and an on signal is output to the pump drive section when the total discharge amount of the battery exceeds a reference discharge amount. This is how it has become.

In this embodiment, a current integrator 52 is used as the discharge detection section, and this current integrator 52 has a function of simultaneously integrating the sum of the discharge electricity ffi (AH) and the self-discharge amount (AH) of the battery. It also has a reset function that is reset (Rset) by the output of a comparator 54, which will be described later. In other words, this current integrator 52 has a system that can add not only the amount of discharged electricity but also the amount of self-discharge using a microcomputer, so that the amount of bromine consumed in the reaction tank 44 can be measured regardless of charging or discharging. It is said that

The output of the current integrator 52 is input to a comparator 53 and a comparator 54, where it is compared with a preset reference discharge 1jk (Ref). As shown in FIG. 2, when the signal from the current integrator 52 exceeds the reference value (REF), the monostable multivibrator 6
An on signal is outputted to the pump drive section 56 via 4.

This pump drive section 56 includes a relay driver 58 and a relay 6.
0 and a pump power supply 62, and when an on signal is input to the pump drive unit 56, this is amplified by the relay driver 58, the relay coil 60a is excited, and the relay contact 60b is closed, and the pump power supply 62 turns on the pump 4.
8 is driven. The monostable multi-vibration break 64 determines the energization time to the pump drive unit 56, and the drive time of the pump 48 is determined as appropriate depending on the circulation speed of the electrolyte and the like.

The current integrator 52 is reset in the above case, for example, when the output of the comparator 54 falls from on to off, and the pump 48 is reset for a certain period of time (T) set by the monostable multivibrator 64. Driven.

In the battery of this example, the bromine concentration in the complex compound gradually decreases with discharge, and the amount of bromine attached to the positive electrode side active layer, that is, the discharge amount, tends to decrease with one electrolyte exchange. If, for example, carbon vapor or carbon cloth is used as the active layer on the positive electrode side, approximately 6 mA H/c of the bromine complex compound will adhere to the electrode surface even at the end of discharge. Therefore, in this embodiment, the conditions of the comparator 54 are set so that the pump is turned on when a discharge of 5 mAH/c- including the amount of self-discharge is performed. In this way, pump on/off is normally controlled by detecting the total amount of discharged electricity (AH), so smooth operation is possible without running out of discharged power even just before the pump is driven. becomes.

Next, another characteristic feature of the invention is that the voltage detection section detects the battery voltage, the discharge detection section detects the total discharge amount including the self-discharge amount of the battery, and the detected voltage and the preset a first comparison calculation unit that compares the detected total discharge amount with a reference voltage set in advance; a second comparison calculation unit that compares the detected total discharge amount with a preset reference discharge amount; and a command from each comparison calculation unit. and a pump drive unit that drives a liquid circulation pump, and when either of the following conditions is satisfied: when the discharge voltage becomes equal to or less than the reference voltage, and when the total discharge amount of the battery exceeds the reference discharge amount, An on-signal is output to the pump driving section.

That is, in this embodiment, as shown in FIG. 3, a DC voltmeter 66 is used as a voltage detection section, and its detection signal is sent to a comparator 68 as a first comparison calculation section.
The voltage is input to the reference voltage Refl, and is compared with a predetermined reference voltage Refl. The comparator 68 is a hysteresis comparator that can separately set conditions for sending an on signal to a pump drive unit 70, which will be described later, and conditions for sending an off signal after the on signal has been sent to the pump. Here, when the voltage detection value detected by the DC voltmeter 66 becomes lower than the reference voltage (Refl), the relay driver 7 of the pump drive unit 72
2, the contact 74b of the relay 74 is closed, and the pump 48 is driven by the pump power source 76, as described above.

Further, a current integrator 78 that simultaneously integrates the sum of the amount of discharged electricity and the amount of self-discharge is used as a discharge detection section that detects the amount of discharged electricity during discharge, and its output is sent to the second comparison calculation section (79 ) is input to the comparator 80. here,
It is compared with a predetermined reference discharge amount (Re f 2), and when the total discharge amount detected by the current integrator 78 exceeds the reference discharge amount, the pump is driven from the comparator 80 via the monostable multi-valve regulator 81. An on signal is output to the relay driver 82 of the section 70, and after this signal is amplified by the relay driver 82, the contact 84b of the relay 84 is closed and the pump 48 is driven.

That is, according to this embodiment, the current integrator is −
In case all the bromine is consumed before the set value is reached, the pump is activated by detecting the battery voltage.

When the electrolyte is circulated in this way, the battery voltage is restored, and when it reaches a specific reference voltage or higher, the pump is turned off.

In each of the above examples, continuous operation of the pump generally generates a large amount of heat and increases the temperature of the electrolyte, so bromine moves from the positive electrode side to the negative electrode side through the separator in the reaction tank. Although battery efficiency decreases, according to the embodiments of the present invention, by operating the pump intermittently, it is possible to reduce heat generation, improve battery efficiency, and extend the life of the pump. Can be done.

In addition, in conventional batteries where the pump is operated continuously, the positive electrode active layer always has as much bromine complex compound attached as possible, and in this case, if the battery is left for a long time, all of the bromine will be consumed by self-discharge. Put it away. However, according to an embodiment of the present invention in which the pump is operated intermittently, the amount of self-discharge can be significantly reduced.

[Effects of the Invention] As explained above, this invention can reduce the amount of self-discharge by operating the pump intermittently, and can also improve battery efficiency by reducing heat generation. .

[Brief explanation of the drawing]

Figure 1 is a system block diagram of a metal-halogen battery with electrolyte circulation according to the present invention, Figure 2 is an explanatory diagram of its operation', Figure 3 is a system block diagram of another invention, and Figure 4 is an electrolyte circulation diagram. 1 is a diagram illustrating the principle of a metal-halogen battery. 44... Reaction tank 46... Electrolyte storage tank 48... Pump 50... Piping 52.78... Current integrator 54.68.80... Comparator 56.70
... Pump drive unit 60.74.84 ... Relay 62.76 ... Pump power supply 64 ... Monostable multi-vibration break 66, ...
DC voltmeter.

Claims (4)

[Claims] (1) The reaction tank formed between the electrode plates 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 transfer the electrolyte on the positive electrode side between the electrolyte storage tank and the reaction tank. and a discharge detection unit that detects the total amount of discharge including the self-discharge amount of the battery in an electrolyte circulation type metal-halogen battery that circulates the negative electrode side electrolyte and performs a predetermined charging/discharging reaction via these electrolytes. , a comparison calculation section that compares the detected total discharge amount with a preset reference discharge amount, and a pump drive section that drives a liquid circulation pump according to a command from the comparison calculation section, An electrolyte circulation type metal-halogen battery, characterized in that an on signal is output to the pump drive unit when the discharge amount exceeds a reference discharge amount. (2) In the battery according to claim (1), the comparison calculation section outputs the ON signal to the pump drive section, and then
An electrolyte circulation type metal-halogen battery characterized by automatically outputting an off signal after a certain period of time has elapsed. (3) The reaction tank formed between the electrode plates 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 transfer the electrolyte on the positive electrode side between the electrolyte storage tank and the reaction tank. In an electrolyte circulation type metal-halogen battery, in which a negative electrode side electrolyte is circulated and a predetermined charging/discharging reaction is performed via these electrolytes, a voltage detection unit that detects the battery voltage and a self-discharge amount of the battery are included. a discharge detection unit that detects a total discharge amount; a first comparison calculation unit that compares the detected voltage with a preset reference voltage; and a first comparison calculation unit that compares the detected total discharge amount with a preset reference voltage. The second to compare with
and a pump drive unit that drives a liquid circulation pump according to commands from the respective comparison calculation units,
The on-signal is output to the pump drive unit when either of the following conditions is satisfied: when the discharge voltage becomes equal to or less than the reference voltage, or when the total discharge amount of the battery exceeds the discharge amount. Features: Metal-halogen battery with electrolyte circulation. (4) In the battery described in claim (3),
The first and second comparison calculation sections output an on signal to the pump drive section and then automatically output an off signal after a certain period of time has elapsed.
halogen battery.