JPH04249075A - Zn-br battery - Google Patents

Abstract

PURPOSE:To provide a Zn-Br battery, whose charged condition can be sensed accurately at any arbitrary temperature. CONSTITUTION:Arrangement according to the present invention is equipped with concentration sensing means 32a,32b and ones 33a, 33b to sense the Zn ion concentration in electrolyte and also with temp. sensing means 31a, 31b. On the basis of temps. sensed by these temp. sensing means 31a, 31b, a calculating device 30 corrects the Zn ion concentration sensed by the concentration sensing means 32a, 32b and the ones 33a, 33b, and the battery charged condition calculated on the basis of the corrected value is displayed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc bromine battery, and more particularly to a zinc bromine battery in which charging and discharging reactions are carried out by circulating an electrolyte.

0002

BACKGROUND OF THE INVENTION A metal-bromine battery, such as a zinc-bromine battery, in which an electrolyte is circulated between an electrolyte storage layer and a reaction tank to carry out predetermined charging and discharging reactions, is known as a new type of battery. A basic electrochemical reaction shown in Formula 1 is carried out in a reaction tank provided with a positive electrode and a negative electrode.

0003

[Formula 1]

0004

As is clear from this reaction equation, zinc Zn is deposited on the negative electrode during charging, and bromine Br2 is deposited on the positive electrode.
is generated and this Br2 is dissolved in the electrolyte. Also,
During discharge, zinc Zn deposited on the negative electrode plate is oxidized to become Zn2+ and dissolved in the electrolyte, and bromine Br2 in the electrolyte is reduced to become bromine ions 2Br- and similarly dissolved in the electrolyte. dissolve in

FIG. 4 shows a conventional zinc-bromine battery formed using such a principle.
A positive electrode 13a and a negative electrode 13b are provided on both sides in the reaction tank 10, and the electrochemical reaction of formula 1 is performed between these electrodes 13a and 13b via an electrolytic solution 12.

In such a zinc-bromine battery, the electrolyte 12
Zinc bromide (ZnBr2) aqueous solution is used as
In addition to this, conductivity improvers, bromine complexing agents,
Contains dendrite inhibitors, etc.

[0008] During charging, the charging reaction shown in equation 1 is carried out in the reaction tank 10, and bromine Br2 is generated and dissolved in the electrolyte 12 at the positive electrode 13a, and zinc Zn is precipitated at the negative electrode 13b. A zinc precipitation layer 22 is gradually formed on the negative electrode 13b.

Furthermore, during discharging, a reaction opposite to that during charging takes place; bromine Br2 is reduced on the positive electrode 13a side and becomes bromine ions 2Br-, which are dissolved in the electrolytic solution 12, and on the negative electrode 13b side, zinc The deposited layer 22 is oxidized to become zinc ions Zn2+ and dissolved in the electrolytic solution 12.

[0010] Reaction tank 1 in which such an electrochemical reaction is carried out
0 indicates that the inside is covered with a separator film 1 to prevent self-discharge from occurring due to bromine Br2 generated during charging.
1 into a positive electrode side reaction tank 10a and a negative electrode side reaction tank 10b.

This separator film 11 allows the electrolytic solution 12 to pass therethrough in order to prevent self-discharge, but it blocks the penetration of bromine Br2 dissolved therein. As such a separator membrane 11, an ion exchange membrane or a porous membrane is generally used, and a porous membrane is used from the viewpoint of reducing the internal resistance of the battery.

In the electrolyte circulation type battery, in order to store the energy obtained by the electrolytic reaction during charging, the positive electrode side electrolyte storage tank 14a and the negative electrode side electrolyte storage tank 14 are used.
b is provided.

The positive electrode side electrolyte storage tank 14a and the positive electrode side reaction tank 10a constitute an electrolyte circulation path via distribution ducts 21a and 17a, and the positive electrode side reaction is carried out by a pump 15a provided in the circulation path. The positive electrode electrolyte 12a that has reacted in the tank 10a is sent to the storage tank 14a, and the new electrolyte 12a stored in the storage tank 14a is transferred to the reaction tank 1.
It is supplied to 0a.

Here, if a bromine complexing agent is added to the electrolytic solution 12, the bromine Br generated during charging
2 is complexed and precipitated as a complex compound insoluble in the electrolytic solution 12, and in the battery shown in FIG. To go.

[0015] Furthermore, this complex storage section 19 and the distribution duct 17
a is connected by a complex supply duct 23 having a valve 20. This valve 20 is normally open, and the complex compound precipitated in the complex storage section 19 is sent out for discharge toward the reaction tank 10a via the distribution duct 17a.

[0016] Furthermore, the negative electrode side electrolyte storage tank 14b is
Similarly, the distribution duct 21 is connected to the negative electrode side reaction tank 10b.
An electrolytic solution circulation path is formed through the electrodes b and 17b, and a pump 15b provided in the circulation path is used to send out the negative electrode side electrolyte 12b reacted in the negative electrode reaction tank 10b toward the storage tank 14b. A new electrolytic solution 12b is supplied from the reactor to the reaction tank 10b.

As described above, this zinc-bromine battery sufficiently stores the electrolyte 12 in the storage tanks 14a and 14b, and when charging using the stored electrolyte 12, the charging reaction shown in equation 1 is performed, A bromine complex compound is stored in the complex storage section 19, and a zinc deposit layer 22 is formed on the negative electrode 13b, so that electric power can be stored. Further, during discharge, the bromine complex compound stored in the complex storage section 19 is sent out toward the positive electrode side reaction tank 10a, and using the complex compound and the zinc precipitation layer 22 formed on the negative electrode 13b, the formula The discharge reaction shown in 1 can be performed and the charging power can be released.

[0018]

[Problems to be Solved by the Invention] Here, as shown in Equation 1, it can be seen that the concentration of zinc ions in the electrolytic solution changes as the battery is charged and discharged. That is, it can be seen that the concentration of zinc ions in the electrolyte decreases when the battery is charged, and that the concentration of zinc ions in the electrolyte increases as the battery is discharged. Therefore, the concentration of zinc ions in the electrolyte is an indicator of the state of charge of the battery, and in fact, the state of charge (SOC) of the battery can be detected by detecting the concentration of zinc ions in the electrolyte. There is.

By the way, in order to detect the concentration of zinc ions in the electrolyte, detection methods based on refractive index, conductivity, density, etc. are used, but since these are temperature dependent, Changes in the temperature of the liquid cause fluctuations in the detected value.

However, the conventional device has the disadvantage that it cannot accurately detect the state of charge because it does not take into account the variation of the detected value due to temperature.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a zinc bromine battery equipped with a detection mechanism that can accurately detect the state of charge of the battery at any temperature. There is a particular thing.

[0022]

[Means for Solving the Problems] In order to achieve the above objects, in the zinc bromine battery of the present invention,
concentration detection means for detecting the zinc ion concentration of the electrolytic solution; temperature detection means for detecting the temperature of the electrolytic solution; and concentration correction for correcting the zinc ion concentration detected by the concentration detection means based on the data of the temperature detection means. and means for detecting the zinc ion concentration of the electrolyte.

[0023]

[Operation] In the zinc bromine battery according to the present invention having the above configuration, the zinc ion concentration of the battery electrolyte detected by the concentration detection means is determined based on the temperature of the electrolyte detected by the temperature detection means. The zinc ion concentration of the electrolyte is corrected, thereby making it possible to accurately detect the zinc ion concentration of the electrolyte at any temperature.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the structure of an embodiment of a zinc bromine battery according to the present invention. Note that the same members and constituent elements as in the conventional example are given the same reference numerals, and their explanations will be omitted.

A characteristic feature of the present invention is that concentration detection means 32a and 32b, 33a and 33b, and temperature detection means 31a and 31b are provided, and these are connected to calculation means 30. Here, the battery is separated into a positive electrode side and a negative electrode side by a separator 11, and there is often a difference in zinc ion concentration between the positive electrode side electrolyte and the negative electrode side electrolyte. The detection means are distributed and installed on the positive electrode side and the negative electrode side, respectively. That is, on the positive electrode side, the positive electrode side electrolyte 12
Concentration detection means 32a and 33a for detecting the zinc ion concentration of the electrolytic solution a are installed, and at the same time, a temperature detection means 31a is installed. On the other hand, on the negative electrode side, concentration measuring means 32b and 33b are installed to measure the zinc ion concentration of the negative electrode side electrolyte, and at the same time, a temperature detecting means 31b is installed.

In the embodiment, the concentration detecting means 32a and 32b use refractive index sensors that detect the zinc ion concentration in the electrolytic solution based on the refractive index, and the concentration detecting means 33a and 33b use refractive index sensors that detect the zinc ion concentration in the electrolytic solution based on the density. A density sensor is used to detect concentration. The zinc ion concentrations of the electrolyte solution detected by these methods are respectively input to the calculating means 30, and the temperature sensor 31a serving as the temperature detecting means
The temperature is corrected based on the temperature of the electrolytic solution detected by and 31b.

FIG. 2 is a block diagram showing the configuration of the calculation means 30. First, the signals from the concentration detection means and temperature detection means are sent to an analog/digital converter (A/D converter).
and is converted into a digital signal here. This digital signal is then input to the microcomputer 40 and compared with the data in the memory 47. Here, in the embodiment, the memory 47 is provided with data determined by the calibration curve method. In other words, since it contains experimental data on changes in the detected zinc ion concentration with respect to temperature, this data can be used to calculate the zinc ion concentration of the electrolyte at any temperature to the concentration in the standard state (25°C). Corrected. Further, the state of charge of the battery calculated based on the corrected zinc ion concentration detection value is displayed on the display section 45.

FIG. 3 is a diagram showing the flow of the concentration correction mechanism of the zinc bromine battery according to the present invention. First, in the embodiment, the refractive index sensors 32a and 32b and the density sensor 3
The zinc ion concentration of the electrolytic solution detected by sensors 3a and 33b is captured in S201, and further, the temperature detected by temperature sensors 31a and 31b is captured in S202. Next, in a temperature comparison step S203, it is compared whether the detected temperature of the electrolytic solution is 25°C. Here, if the temperature of the electrolyte is 25°C, the zinc ion concentration of the electrolyte taken in the concentration detection step S201 is determined as the zinc ion concentration of the electrolyte of this battery in S205. At the same time, the display unit 45 displays the charging state of the battery calculated based on this value. However, if the temperature of the electrolytic solution is not 25° C., correction is performed in S204 based on the calibration curve data stored in the memory 47. In this way, the zinc ion concentration of the electrolyte at any temperature taken in S201 is corrected to the zinc ion concentration at the standard state of 25°C, and then this correction value is used to accurately determine the electrolyte of the battery. The zinc ion concentration is determined in S205. Further, the state of charge of the battery calculated based on the correction value is displayed on the display section 45. In this example, a density sensor and a refractive index sensor were used as the concentration detection means, but other concentration detection means could be used, such as using this as a means of detecting the zinc ion concentration of the electrolyte based on the electrical conductivity of the electrolyte. Of course, the same effect can be obtained even if the method is used, as long as it can accurately detect the zinc ion concentration of the electrolyte. Furthermore, as a means of correcting the zinc ion concentration, a calibration curve method was used in this example to correct the zinc ion concentration. Any means for temperature correction may be used, and the present invention is not limited to these as long as the temperature dependence of the detected zinc ion concentration value can be detected. Further, in this embodiment, two types of concentration detection means and two sets of concentration detection means and one pair of temperature detection means are used, but these combinations are not limited to these. Therefore, the ratio of concentration detecting means to one temperature detecting means is not limited to 2 as in this embodiment, and may be other than 2 without any problem.

[0029]

[Effects of the Invention] In the zinc bromine battery according to the present invention having the above-described configuration, since the accurate state of charge of the battery can be known, it is possible to accurately control the machine that uses this battery. It becomes like this.

At the same time, since the temperature of the electrolyte is taken into consideration when periodically calibrating the density measuring means, more accurate calibration can be performed.

Furthermore, since the temperature of the battery can be controlled more precisely, there is also the advantage that the battery life can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a zinc bromine battery according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of an arithmetic device used in this embodiment.

FIG. 3 is a flowchart showing the flow of the concentration correction mechanism of the zinc bromine battery in this embodiment.

FIG. 4 is a diagram showing the structure of a conventional zinc bromine battery.

[Explanation of symbols]

Claims (1)

[Claims] 1. A zinc bromine battery that performs charging and discharging reactions by circulating an electrolytic solution, comprising a concentration detecting means for detecting the concentration of zinc ions in the electrolytic solution, a temperature detecting means for detecting the temperature of the electrolytic solution, and a temperature detecting means for detecting the temperature of the electrolytic solution. and a concentration correction means for correcting the zinc ion concentration of the electrolyte detected by the concentration detection means based on the data of the means, and detecting the corrected zinc ion concentration of the electrolyte at an arbitrary temperature. A zinc bromine battery featuring: