JPS63291365A - Redox flow type battery - Google Patents

Abstract

PURPOSE:To make it possible to eliminate bad effects on the battery performance by providing electrolyte reversing devices in piping systems for supplying electrolyte to an electrolytic cell. CONSTITUTION:For normal operation, electromagnetic valves 21a, 22a, 21b, 22b of electrolyte reversing devices 25a and 25b are opened, whole the other electromagnetic valves are all closed, and pumps 9 and 10 are actuated for circulating electrolyte. The electrolyte goes from a piping system 1 to an electrolytic cell part 6 in the direction shown by an arrow of a continuous line for both of the positive and negative pole sides, and gets out of a piping system 2 in the direction of an arrow of a dot line to return to each electrolyte tank 7 and 9. As a result, electrolyte does not go through piping systems 3 or 4. If a phenomenon which seems to give bad effects on the battery performance in the middle of charge and discharge, the electrolyte reversing devices 25a and 25b are actuated for reversing electrolyte so as to eliminate fluff in carbon deposited in a liquid discharge side slit, not illustrated, or the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a redox flow battery, and more specifically, the present invention relates to a redox flow battery, and more specifically, the present invention relates to a redox flow type battery, and more specifically, to a redox flow type battery, and more specifically, to prevent the formation of an electrolyte flow path caused by fluff detached from a carbon fiber electrode mixed in an electrolyte. The present invention relates to a redox flow battery in which a clogging removal means is attached to the electrolyte piping.

[Conventional technology] Redox flow batteries store surplus power during off-peak periods and release it during peak periods, thereby providing power throughout the day and night.
The aim is to achieve load leveling that eliminates load fluctuations in power demand during early opening hours during the week, and has the feature of adjusting output by changing the capacity of the electrolyte storage tank, which is the active material. .

The redox flow battery is currently under development and is not a practical battery. However, for example, as a stacked electrolyte flow type battery for experimental use, there is one that has been filed as Japanese Patent Application No. 42791/1983. FIG. 4 is a schematic illustration of a redox flow type battery formed from a single cell, which is the basic configuration of this battery.

In Figure 4, 1 is a positive electrode, 2 is a negative electrode, and this electrode 1
and 2 form an electrolytic cell, and a positive electrode chamber 4 and a negative electrode chamber 5 are formed with the ion exchange membrane 3 as a partition wall, and constitute an electrolytic cell section 6 forming a single cell. Moreover, 7 and 8 are a positive electrode electrolyte tank and a negative electrode electrolyte tank, respectively, and are filled with electrolyte solutions in which respective battery active materials are dissolved. The positive φ negative electrode electrolyte tanks 7 and 8 are connected to the positive electrode chamber 4 and the negative electrode chamber 5 by piping, respectively, and a pump 9. Each electrolytic solution is circulated by lO during battery operation, that is, during charging and discharging.

With the above configuration, the output of the redox flow battery is outputted as AC by the converter 11 that converts the battery voltage into AC, and this AC output supplies power to the power plant 13 and the customer 14 via the substation equipment 12. , which functions as a power storage battery.

Incidentally, the unit cell forming the electrolytic cell of the above battery is composed of a plurality of members as shown in FIG. In other words, the bipolar electrode used in the stacked electrolytic cell is
It is composed of a positive electrode 1 and a negative electrode 2 sandwiching a bipolar plate 15, and both the positive electrode 1 and the negative electrode 2 are made of the same carbon cloth. The stacked electrolytic cell includes a bipolar plate 15, positive and negative electrodes 1 and 2, an ion exchange membrane 3, electrode support frames 1a and 2a, and a support frame 15 for the bipolar plate 15.
Using a as a component, electrodes 1.2 are alternately stacked via an ion exchange membrane 3 and a bipolar plate 15, and a positive electrode chamber 4 is formed.
and constitutes a negative electrode chamber 5. In addition, 1B, 16
17.17a is a manifold for positive electrode electrolyte, and 17.17a is a manifold for negative electrode electrolyte.

Each electrolyte for positive and negative electrodes is provided in electrode support frames 1a and 2a.
.

15a and a manifold 16 provided on the ion exchange membrane 3
, 16a and 17.17a to each electrode chamber. This situation is shown in the front explanatory view of FIG. 6 for the case of the negative electrode 2 in the case of a single cell, and the typical flow of the electrolytic solution is shown in the schematic explanatory view of FIG. 7.

In FIG. 6, the electrolytic solution flowing through the liquid inlet manifold 17 is transferred to the liquid inlet provided between the liquid inlet manifold 17 and a notch 19 provided on the electrode chamber 5 side near this manifold 17. It passes through the side slit hole 20 and enters the liquid inlet side pool part 18 of the electrode chamber, passes through the negative electrode 2 part and enters the liquid outlet side liquid pool part 18a, the liquid outlet side notch part 19a, and the liquid outlet side slit hole 20a. through the liquid outlet side manifold 17a
It is then transferred to the next negative electrode chamber.

As shown by the arrows in Fig. 7, during normal operation, the electrolytes for both the positive and negative electrodes are connected to the liquid inlet side piping system 31a (
It enters the electrolytic cell section 6 from the negative electrode side) and 31b (positive electrode side),
The pump 9 follows the liquid flow path from the electrolytic cell section 6 through the liquid outlet piping system 32a (negative electrode side) and 32b (positive electrode side).
and 10, respectively.

Above, we have mainly explained the structure of the electrolytic cell of the redox flow battery, but since the principle of operation is already a well-known technology, we will omit the explanation. I limited myself to only explaining the configuration of the piping system.

When the electrolyte is sent into the cell through the manifold section and slit holes, this electrolyte has conductivity, so when current flows through the battery, the current flowing through these liquid paths becomes a loss current (shunt current loss). , which causes a decrease in current efficiency. The amount of current loss is proportional to the slit diameter and inversely proportional to the slit length. Furthermore, currently,
The commonly used slit hole diameter is 0.5 to 2.0
It is about ms.

In addition, the carbon cloth used as the electrode is activated to improve battery performance, and this treatment reduces the tendency for carbon fibers to fluff when the electrolyte flows through the electrode. have.

[Problems to be solved by the invention] In order to improve battery performance, the electrode structure of the conventional redox flow battery as described above adopts a measure to reduce shunt current loss by providing the above-mentioned slit portion. Therefore, as mentioned above, the fiber particles generated from the carbon cloth forming the electrode are likely to accumulate particularly in the electrolyte outlet side slit. For this reason, there is a problem that the liquid flow path (and the slit portion) in the electrode chamber is clogged by the fluff, making it impossible to supply a predetermined amount of electrolytic solution or increasing pressure loss.

Furthermore, if only a portion of the stacked electrode chambers becomes clogged, the electrolyte cannot be distributed evenly to each electrode chamber, which adversely affects battery performance.

In other words, if some fluff accumulates in the liquid outlet side slits of some of the stacked electrode chambers, the liquid pressure in the electrode chamber will be slightly lower than the liquid pressure in other adjacent electrode chambers through the bipolar plate and ion exchange membrane. As a result, in the electrode chamber where the fluff has accumulated, a slight gap is created between the electrode and the ion exchange membrane. At this time, the electrolytic solution flows within this electrode chamber preferentially through this gap, causing stagnation in the electrolytic solution within the electrode. This stagnation of the electrolyte within the electrode chamber is one of the things that most adversely affects the battery performance due to the characteristics of the redox flow battery.

Furthermore, if the electrode fuzz generated in the cell accumulates in the liquid outlet side slit hole and blocks the liquid flow path, especially if it is in the negative electrode part, it becomes a cause of hydrogen generation.

This invention was made in order to solve the above problem, and as mentioned above, when fine particle fluff generated from the electrode material accumulates in the slit etc. and blocks the liquid flow path, The purpose is to obtain a redox flow battery with a piping system that can eliminate the negative effects on battery performance by adding a clogging removal means that removes the accumulation of fluff by reversing the direction. It is something.

[Means for Solving the Problems] The redox flow battery according to the present invention has an electrolyte backflow device attached to the piping system that supplies electrolyte to the electrolytic cell.

[Function] In this invention, an electrolyte backflow device is provided in addition to the piping system that supplies electrolyte to the electrolytic cell, and this prevents an increase in pressure loss, an increase in cell resistance, and generation of hydrogen before a predetermined charging rate is reached. If a phenomenon that is thought to be caused by clogging of fluff from the electrode is confirmed, the liquid inlet and outlet sides of the manifold and slit holes are reversed, and the flow of the electrolyte is reversed. The fluff accumulated in the slit holes is removed by this liquid backflow. Therefore, after performing the above-mentioned clogging removal work, it is possible to restore the battery to normal operation again.

[Example] FIG. 1 is a schematic illustration of a redox flow battery showing an example of the present invention. In the figures, the numbers 1 to 11 and 31a, 31b, 32a and 32b are the same as those in Figures 4 and 7.
This is the same part as the part used to explain the figure.

In this example, since both the positive electrode side and the negative electrode side have the same configuration, the negative electrode side will be mainly described.

As shown in FIG. 1, the electrolyte piping system of the redox flow battery of the present invention consists of a liquid inlet pipe 31a of system 1 that connects the negative electrode liquid tank 8 and the negative electrode chamber 5, and a liquid outlet pipe 31a of system 2. An electrolyte backflow device 25a indicated by a dotted frame is attached to the side pipe 32a so that the liquid path can be opened and closed freely.

That is, this electrolyte backflow device 25a includes a branch pipe 26a%Va electromagnetic valve 21a and a branch pipe 27a in the pipe 31a shown in system 1, and a branch pipe 28a in the pipe 32a shown in system 2.
The VA3 solenoid valve 23a is connected to the piping 33a shown in System 3, which connects the Sva2 solenoid valve 22a and the branch pipe 29a, and connects the branch pipe 26a and the branch pipe 29a, and the system 4 connects the branch pipe 27a and the branch pipe 28a. It is composed of a piping system in which VA4 electromagnetic valves 24a are connected to piping 34a, respectively.

Similarly, a branch pipe 2 is connected to the positive electrode side pipes 31b and 32b.
Bb, 27b, 28b and 29b and solenoid valve 21b (
V5. ).

22b (V), 23b (V), and 24b (V, 4) are connected to an electrolytic solution backflow device 25b configured by the same assembly as in the case where b2 and b3 are on the negative electrode side.

The operation of the conventional electrolyte backflow device attached to the piping system as described above will be described below.

FIG. 2 is an explanatory diagram showing the operation of the electrolyte flow during normal charging and discharging. During normal operation, the solenoid valves 21a (Val) and 22a (
V ), 21b (V, ) and 22b (v,
2) is opened, and the remaining electromagnetic valves are all closed, and the pump 9 and IO are operated to circulate the electrolyte. The electrolyte is positive
Both negative electrode sides enter the electrolytic cell section 6 from the piping system 1 in the direction shown by the solid arrow, exit through the piping system 2 in the direction of the dotted arrow, and return to each electrolyte tank 7 and 8, so the electrolyte flows into the piping system 3. and system 4 are not allowed to pass.

Figure 3 shows that when phenomena that appear to have a negative impact on battery performance, such as an increase in pressure loss or an increase in cell resistance, occur during charging and discharging, deposits are deposited on the liquid outlet side slit hole 20a, etc., as described above. Electrolyte backflow device 25 is used to remove fluff from the carbon cloth.
It is an explanatory diagram of operation when actuating a and 25b to reverse flow the electrolyte.

That is, during the electrolyte backflow operation, the solenoid valve 23a (V
a3), 24a (Va4), 23b (vb3) and 24
b (vb4) is opened, and the remaining electromagnetic valves are all closed, and the pumps 9 and 10 are operated to circulate the electrolyte. The electrolytic solution for both the positive and negative electrodes passes from piping system 1 to system 3, passes through the piping system of system 2, and enters the electrolytic cell as shown by the solid line arrow, and then from system 1 to system 4.
It passes through system 2, exits as shown by the dotted arrow, and flows backwards.

The liquid flow modes and solenoid valve operation procedures shown in FIGS. 2 and 3 are summarized in Table 1.

Table 1 Note that in the above embodiment, a case has been described in which a solenoid valve is used as an on-off valve, but it goes without saying that the same effect can be obtained even if other valves having the same function are used.

[Effects of the Invention] As explained above, the present invention incorporates an electrolyte backflow device that switches the flow of the electrolyte into the electrolyte supply plant system of a redox flow battery, thereby eliminating the problem in the case where electrode fluff accumulates in the slit hole on the liquid outlet side. , it becomes possible to reverse the flow of the liquid, remove the accumulated fluff, and easily return to normal flow.

Therefore, the pressure drop increases due to clogging of the slits caused by the inevitable occurrence of electrode fluff in conventional redox flow batteries, the inability to supply a predetermined amount of electrolyte, and the inability to equally distribute electrolyte to each cell. Problems that are considered to have an adverse effect on battery performance, such as the following, are resolved, and this is effective in maintaining good battery performance.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of a redox flow type battery showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of electrolyte flow operation during normal operation of the battery of Fig. An explanatory diagram of the electrolyte flow operation during electrolyte backflow operation of the battery, Figure 4 is a schematic diagram of a conventional redox flow type battery, and Figure 5 is an explanation of the single cell configuration forming the electrolytic cell of a conventional stacked battery. FIG. 6 is an explanatory diagram of the electrode support frame and the flow of electrolyte in the negative electrode chamber, and FIG. 7 is an explanatory diagram of the flow of electrolyte in normal electrolyte piping. In the figure, 21a, 22a, 23a and 24a are solenoid valves on the negative side piping, 21b, 22b, 23b and 24b are solenoid valves on the positive side piping, 26a, 27a, 28a and 29a are branch pipes on the negative side piping, 26b, 27b, 28b
29b is a branch pipe of the positive electrode side piping, 25a is an electrolyte backflow device on the positive electrode side, and 25b is an electrolyte backflow device on the positive electrode side. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A redox flow battery having an electrolyte circulation layered structure and having a piping system connecting an electrolytic cell and an electrolyte tank, characterized in that an electrolyte backflow device is attached to the piping system. Redox flow battery.