KR20190110219A - Redox flow battery(rfb) using electrolyte concentration gradient and operation method thereof - Google Patents

Abstract

The present invention relates to a redox flow battery using an electrolyte concentration gradient and an operating method thereof, capable of increasing the efficiency of a redox flow battery. To this end, the redox flow battery of the present invention comprises: a positive electrode electrolyte tank having an electrolyte inlet at an upper end thereof, an electrolyte outlet at a lower end thereof, and a partitioning plate for forming a concentration gradient of a positive electrode electrolyte accommodated therein; a negative electrode electrolyte tank having an electrolyte inlet at an upper end thereof, an electrolyte outlet at a lower end thereof, and a partitioning plate for forming a concentration gradient of a negative electrode electrolyte accommodated therein; and a stack unit for receiving electrolytes from the positive and negative electrolyte tanks to charge and discharge power.

Description

REDOX FLOW BATTERY (RFB) USING ELECTROLYTE CONCENTRATION GRADIENT AND OPERATION METHOD THEREOF}

The present invention relates to a redox flow battery using an electrolyte concentration gradient and a method of operating the same, and more particularly, to a redox flow cell using an electrolyte concentration gradient capable of increasing the efficiency of a redox flow battery and a method of operating the same. It is about.

Electric power storage technology is an important technology for efficient use of the entire energy, such as efficient use of electric power, improvement of the power supply system's ability and reliability, the introduction of renewable energy that fluctuates over time, and the energy regeneration of the moving body. There is an increasing demand for possibilities and social contributions.

Adjusting the supply and demand balance of semi-autonomous regional power supply systems such as microgrids and properly distributing non-uniform outputs of renewable energy generation such as wind and solar power, and voltage and frequency fluctuations resulting from differences from existing power systems In order to control the effect of the secondary battery is being actively researched and the expectation of the utilization of the secondary battery in these fields is increasing.

In particular, when looking at the characteristics required for the secondary battery to be used for high-capacity power storage, the energy storage density should be high, and redox flow battery (RFB) has been in the spotlight as a secondary battery of high capacity and high efficiency suitable for such characteristics. There is a situation.

The redox flow battery converts electrical energy input through a charging process into chemical energy and stores the same as a general secondary battery, and converts previously stored chemical energy into electrical energy through a discharge process. However, such a redox flow battery is different from a general secondary battery in that a tank for storing the electrode active material is required because the electrode active material having energy exists in a liquid state rather than a solid state.

In the case of a general redox flow battery, one tank connected to the anode and the cathode and storing the electrolyte solution is installed. The electrolyte stored in the tank is discharged from the tank to the stack to react (charge or discharge) in the stack, and after the reaction is circulated back to the tank, a concentration gradient of the electrolyte is formed in the tank. The concentration gradient thus formed is quickly resolved by natural diffusion, convection, or artificial agitation.

However, when it is used without resolving the concentration gradient of the naturally generated electrolyte solution, it is judged that the effect of improving the efficiency of the entire battery can be obtained, thus leading to the present invention.

Republic of Korea Patent Publication No. 10-2017-0077720

The present invention is to solve the above problems, it is an object of the present invention to provide a redox flow battery and its operation method that can improve the efficiency of the entire battery using the concentration gradient of the naturally formed electrolyte.

These and other objects and advantages of the present invention will become apparent from the following description of preferred embodiments.

The object includes an anode electrolyte tank having an electrolyte inlet at the top, an electrolyte outlet at the bottom, and a partition plate for forming a concentration gradient of the anode electrolyte contained therein; An anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower end, and having a partition plate for forming a concentration gradient of the cathode electrolyte contained therein; And a stack unit configured to receive electrolyte from a cathode electrolyte tank and a cathode electrolyte tank to store and discharge electric power.

At this time, the partition plate provided in the anode electrolyte tank, may be installed in a horizontal direction, may be a plurality, a plurality of partition plates, are installed in a horizontal direction, adjacent partition plates are coupled to the opposite side of the anode electrolyte tank It is preferable to be.

In addition, partition plates provided in the cathode electrolyte tank may be installed in a horizontal direction, there may be a plurality of partition plates, a plurality of partition plates are installed in the horizontal direction, adjacent partition plates are coupled to the opposite side of the cathode electrolyte tank It is preferable to be.

On the other hand, the stack portion includes at least one battery cell, and the battery cell includes an ion exchange membrane; An anode positioned with an ion exchange membrane interposed therebetween; And a cathode.

In addition, a pump for transferring the cathode electrolyte contained in the anode electrolyte tank to the stack portion; may include, or may include a pump for transferring the cathode electrolyte solution contained in the cathode electrolyte tank to the stack portion.

In addition, the object includes a first anode electrolyte tank having an electrolyte inlet at the top, an electrolyte outlet at the bottom, and a partition plate for forming a concentration gradient of the anode electrolyte contained therein; A second anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower end, and a partition plate for forming a concentration gradient of the anode electrolyte contained therein; A first cathode electrolyte tank having an electrolyte inlet at an upper end thereof, an electrolyte outlet at the bottom thereof, and a partition plate for forming a concentration gradient of the cathode electrolyte contained therein; A second cathode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower part thereof, and a partition plate for forming a concentration gradient of the cathode electrolyte contained therein; And a stack unit configured to receive electrolyte from the first and second anode electrolyte tanks and the first and second cathode electrolyte tanks to store and discharge electric power. have.

In this case, the partition plates provided in the first and second anode electrolyte tanks may be installed in a horizontal direction, and may be a plurality of partition plates, and the plurality of partition plates may be installed in a horizontal direction, and adjacent partition plates may be formed in a first direction. And on the opposite side in the second anode electrolyte tank.

In addition, the first positive electrode electrolyte tank and the second positive electrode electrolyte tank may be connected to a connector through which the positive electrode electrolyte contained therein may be moved, and the connector may include a compartment provided in the first positive electrode electrolyte tank and the second positive electrode electrolyte tank. It is desirable to be located at a point higher than the plate.

In addition, the first positive electrode electrolyte tank and the second positive electrode electrolyte tank, may be provided with an extension pipe connected to the electrolyte inlet so that each of the positive electrode electrolyte flowing into the lower end of the tank.

In addition, the partition plates provided in the first and second cathodic electrolyte tanks may be installed in a horizontal direction, and may be a plurality of partition plates, and the plurality of partition plates may be installed in a horizontal direction, and adjacent partition plates may be formed in a first direction. And on the opposite side in the second cathode electrolyte tank.

In addition, the first cathode electrolyte tank and the second cathode electrolyte tank may be connected to a connector through which the cathode electrolyte contained therein may be moved, and the connector may include a compartment provided in the first cathode electrolyte tank and the second cathode electrolyte tank. It is desirable to be located at a point higher than the plate.

In addition, the first cathode electrolyte tank and the second cathode electrolyte tank may include an extension pipe connected to the electrolyte inlet so that the cathode electrolyte introduced into the tank may be introduced into the lower end of the tank, respectively.

On the other hand, the stack portion includes at least one battery cell, and the battery cell includes an ion exchange membrane; An anode positioned with an ion exchange membrane interposed therebetween; And a cathode.

In addition, the pump may be configured to transfer the anode electrolyte contained in the first and second anode electrolyte tanks to the stack portion. The pump may transfer the anode electrolyte contained in the first and second cathode electrolyte tanks to the stack portion. have.

The control unit may include a control unit installed in the electrolyte passages connected to the first and second anode electrolyte tanks and the first and second cathode electrolyte tanks, respectively, to control valves for controlling opening and closing of the passages.

According to the present invention, an overpotential in the stack portion is formed by extending the movement path of the electrolyte solution through a partition plate provided in the tank to form a concentration gradient of the electrolyte solution in the tank, and transferring the electrolyte solution having a higher concentration of the reactant to the stack portion. It can have an effect that can reduce the overpotential).

Furthermore, this may allow charging or discharging to occur with a larger current, increase the voltage efficiency, and consequently have the effect of increasing the efficiency of the entire battery.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a view schematically showing a redox flow battery according to an embodiment of the present invention.
2 is a view schematically showing a redox flow battery according to an embodiment of the present invention.
3 is a view schematically showing a redox flow battery according to an embodiment of the present invention.
4 is a view schematically showing the charging process of the redox flow battery of FIG.
5 is a view schematically showing a discharge process of the redox flow battery of FIG.
FIG. 6 is a graph illustrating a comparison of voltage and state of charge (SoC) of a vanadium redox flow battery having a partition plate and a vanadium redox flow battery according to an embodiment of the present invention. to be.
7 is an enlarged graph illustrating an end point of charging of FIG. 6.
8 is an enlarged graph illustrating an end point of discharge of FIG. 6.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

Also, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and in the case of conflict, the specification including definitions The description of will prevail.

In the drawings, parts irrelevant to the description are omitted to clearly describe the proposed invention, and like reference numerals designate like parts throughout the specification. In addition, when a part "contains" a certain component, this means that the component may further include other components, without excluding other components, unless specifically stated otherwise. In addition, the "unit" described in the specification means one unit or block that performs a specific function.

In each step, an identification code (first, second, etc.) is used for convenience of description, and the identification code does not describe the order of each step, and each step does not explicitly describe a specific order in context. It may be carried out in a different order than described above. That is, each step may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

In the present specification, the flow cell may be a flow cell including various known active materials. Here, for the convenience of description, the vanadium flow battery is described as an example, but is not limited thereto.

1 is a view schematically showing a redox flow battery according to an embodiment of the present invention. Referring to FIG. 1, a redox flow battery according to an embodiment of the present invention includes an electrolyte inlet 11 at an upper end thereof, an electrolyte outlet 12 at a lower end thereof, and an anode electrolyte contained therein. An anode electrolyte tank 10 having a partition plate 13 for forming a concentration gradient; An anode electrolyte tank 20 having an electrolyte inlet 21 at an upper end thereof, an electrolyte outlet 22 at a lower end thereof, and a partition plate 23 for forming a concentration gradient of an anode electrolyte contained therein; And a stack unit 30 that receives the electrolyte solution from the anode electrolyte tank 10 and the cathode electrolyte tank 20 to store and discharge electric power. The present invention extends the movement path of the electrolyte solution through the partition plate 13 provided in the tank to form a concentration gradient of the electrolyte solution in the tank, and stacks the electrolyte solution having a higher concentration of the reactant in the charging or discharging process. By transferring to) it can have an effect that can reduce the overpotential (overpotential) in the stack (30). Through this, charging or discharging may occur with a larger current, voltage efficiency may be increased, and consequently, the efficiency of the entire battery may be increased.

The cathode electrolyte tank 10 is to accommodate the anode electrolyte therein, and may be formed in various forms such as a cylindrical shape. An electrolyte inlet 11 is provided at an upper end thereof to allow anolyte electrolyte to flow in, and an electrolyte electrolyte outlet 12 is provided at a lower end of the cathodic electrolyte to be accommodated. At the front end of the electrolyte inlet 11 and the rear end of the electrolyte outlet 12, valves 14 and 15 may be installed to control the opening and closing of the flow path, respectively. A partition plate 13 may be provided in the cathode electrolyte tank 10 to form a concentration gradient of the anode electrolyte flowing therein. That is, the partition plate 13 may control the flow path of the anode electrolyte to form an electrolyte concentration gradient until the anode electrolyte flowing into the inlet 11 from the inside of the anode electrolyte tank 10 flows out to the outlet 12. Can be. The partition plate 13 may be manufactured in any form as long as it can control the flow path of the positive electrolyte, and may be, for example, a plate shape. In addition, the partition plate 13 is preferably formed in a horizontal direction (see FIG. 1) to smoothly flow the anode electrolyte, and may be formed in plural. At this time, the partition plate 13 is formed in the horizontal direction so that the flow path is longest (zigzag flow) while the flow of the positive electrolyte is smooth, and the concentration gradient of the positive electrolyte is increased. The silver is preferably coupled to opposite sides of the positive electrolyte tank 10 with respect to the longitudinal section of the positive electrolyte tank 10 (see FIG. 1).

The negative electrolyte tank 20 is to accommodate the negative electrolyte therein, it may be formed in various forms such as cylindrical. An electrolyte inlet 21 is provided at an upper end thereof so that a negative electrolyte flows in, and an electrolyte outlet 22 is provided at an lower end thereof so that a negative electrolyte solution accommodated therein flows out. At the front end of the electrolyte inlet 21 and the rear end of the electrolyte outlet 22, valves 24 and 25 may be installed to control opening and closing of the flow path, respectively. In the negative electrolyte tank 20, a partition plate 23 may be provided to form a concentration gradient of the negative electrolyte flowing therein. That is, the partition plate 23 may control the flow path of the cathode electrolyte to form an electrolyte concentration gradient until the anode electrolyte flowing into the inlet 21 from the inside of the cathode electrolyte tank 20 flows out to the outlet 22. Can be. The partition plate 23 may be manufactured in any form as long as it can control the flow path of the cathode electrolyte. For example, the partition plate 23 may have a plate shape. In addition, the partition plate 23 is preferably formed in a horizontal direction (see FIG. 1) to smoothly flow the cathode electrolyte, and may be formed in plural. At this time, the partition plate 23 is formed in a horizontal direction so that the flow path is longest (zigzag flow) while the flow of the cathode electrolyte is smooth, and the concentration gradient of the cathode electrolyte is increased. The silver is preferably coupled to opposite sides of the negative electrolyte tank 20 with respect to the longitudinal section of the negative electrolyte tank 20 (see FIG. 1).

The stack unit 30 may include one or a plurality of battery cells. The battery cell may include a positive electrode 32 and a negative electrode 33 positioned with the ion exchange membrane 31 and the ion exchange membrane 31 interposed therebetween. The anode 32 and the cathode 33 may be made of a variety of known materials, for example, may be made of graphite. The ion exchange membrane 31 preferably has high selectivity for ions, small electrical resistance, small diffusion coefficients of solutes and solvents, chemical stability, excellent mechanical strength, and economical efficiency. In general, Nafion (Dupnot), CMV, AMV, DMV (Asahi Glass) and the like can be used. In the case of vanadium-based redox flow batteries, however, an active material mixed with a transition metal element and a strong acid is used as an electrolyte. Therefore, a membrane having high acid resistance, oxidation resistance, and permeability is required. When applying a Nafion membrane to a vanadium battery, Due to the permeation, the energy efficiency is low, and in the case of the CMV membrane, the lifespan characteristics are poor. Therefore, in order to compensate for these disadvantages, an ion exchange membrane using an engineering plastic polymer having excellent mechanical properties in a strong acid atmosphere and a high temperature region may be applied. For example, polyether ether ketone (PEEK), polysulfone (PSF), and polybenzimidazole ) Can be used.

In addition, pumps 40a and 40b may be further included to transfer the cathode electrolyte contained in the cathode electrolyte tank 10 and the cathode electrolyte contained in the cathode electrolyte tank 20 to the stack unit 30, respectively.

2 is a view schematically showing a redox flow battery according to an embodiment of the present invention. Referring to Figure 2, the redox flow battery according to an embodiment of the present invention has an electrolyte inlet (11a) at the top, and the electrolyte outlet (12a) at the bottom, of the positive electrolyte contained therein A first positive electrode electrolyte tank 10a having a partition plate 13a for forming a concentration gradient; The second anode electrolyte tank 10b having an electrolyte inlet 11b at the top, an electrolyte outlet 12b at the bottom, and a partition plate 13b for forming a concentration gradient of the anode electrolyte contained therein. ); The first cathode electrolyte tank 20a having an electrolyte inlet 21a at the top, an electrolyte outlet 22a at the bottom, and a partition plate 23a for forming a concentration gradient of the cathode electrolyte contained therein. ); Second anode electrolyte tank 20b having an electrolyte inlet 21b at the top, an electrolyte outlet 22b at the bottom, and a partition plate 23b for forming a concentration gradient of the cathode electrolyte contained therein. ); And a stack unit 30 that receives and receives an electrolyte from the first and second anode electrolyte tanks 10a and 10b and the first and second cathode electrolyte tanks 20a and 20b to store and discharge electric power. It includes; The present invention includes a plurality of anode electrolyte tanks 10a and 10b and cathode electrolyte tanks 20a and 20b, and extends a movement path of the electrolyte solution through partition plates 13a, 13b, 23a, and 23b provided in the tank. By forming a concentration gradient of the electrolyte in the tank, by transferring the electrolyte having a higher concentration of the reactant to the stack portion 30 during the charging or discharging process to have an effect that can reduce the overpotential in the stack portion Can be. Through this, charging or discharging may occur with a larger current, voltage efficiency may be increased, and consequently, the efficiency of the entire battery may be increased.

The first anode electrolyte tank 10a accommodates the anode electrolyte therein, and may be formed in various shapes such as a cylindrical shape. An electrolyte inlet 11a is provided at an upper end thereof to allow anolyte electrolyte to flow in, and an electrolyte electrolyte outlet 12a is provided at a lower end of the cathodic electrolyte to be accommodated. At the front end of the electrolyte inlet 11a and the rear end of the electrolyte outlet 12a, valves 14a and 15a may be installed to control opening and closing of the flow path, respectively. A partition plate 13a may be provided in the first anode electrolyte tank 10a to form a concentration gradient of the cathode electrolyte flowing therein. That is, the partition plate 13a may control the flow path of the positive electrolyte so that the electrolyte concentration gradient may be formed from the inside of the first positive electrolyte tank 10a until the positive electrolyte flows out of the outlet 12a. The partition plate 13a may be manufactured in any form as long as it can control the flow path of the positive electrolyte, and may be, for example, a plate shape. In addition, the partition plate 13a is preferably formed in a horizontal direction (see FIG. 2) so as to smoothly flow the anode electrolyte, and may be formed in plural. At this time, the partition plate 13a is formed in a horizontal direction so that the flow path is longest (zigzag flow) while the flow of the anode electrolyte is smooth, and the concentration gradient of the anode electrolyte is increased. Silver is preferably coupled to opposite sides of the first anode electrolyte tank 10a with respect to the longitudinal section of the first anode electrolyte tank 10a (see FIG. 2).

The second anode electrolyte tank 10b is structurally identical to the first cathode electrolyte tank 10a. Therefore, in the overlapping part mentioned above, the description is abbreviate | omitted and the part which was not demonstrated above, such as the connection relationship of the 1st positive electrode electrolyte tank 10a and the 2nd positive electrode electrolyte tank 10b, is demonstrated.

The first positive electrode electrolyte tank 10a and the second positive electrode electrolyte tank 10b may be connected to the connector 16 so that the positive electrode electrolyte contained therein may move in both directions. In addition, the first positive electrode electrolyte tank 10a and the second positive electrode electrolyte tank 10b respectively have electrolyte inlets 11a and 11b such that the positive electrode electrolyte introduced into the tank through the electrolyte inlets 11a and 11b is introduced into the lower end of the tank. And extension pipes 17a and 17b connected to each other. At this time, the cathode electrolyte flowing into the lower portion is moved to the adjacent tank through the connection pipe 16 (for example, after flowing into the first anode electrolyte tank 10a, it flows out to the second anode electrolyte tank 10b). When the positive electrode electrolyte has the longest path of movement to form a large concentration gradient, the connecting pipe 16 may include partition plates provided in the first positive electrode electrolyte tank 10a and the second positive electrode electrolyte tank 10b. In the case of a plurality, it is preferably located at a point higher than the highest partition plate (13a, 13b).

The first cathode electrolyte tank 20a accommodates the cathode electrolyte therein, and may be formed in various shapes such as a cylindrical shape. An electrolyte inlet 21a may be provided at an upper end thereof to allow a negative electrolyte to flow therein, and an electrolyte outlet 22a provided at an lower end thereof to allow the negative electrolyte to be accommodated to flow out. At the front end of the electrolyte inlet 21a and the rear end of the electrolyte outlet 22a, valves 24a and 25a may be installed to control opening and closing of the flow path, respectively. A partition plate 23a may be provided in the first cathode electrolyte tank 20a to form a concentration gradient of the cathode electrolyte flowing therein. That is, the partition plate 23a may control the flow path of the cathode electrolyte to form an electrolyte concentration gradient until the cathode electrolyte flows out of the outlet 22a in the first cathode electrolyte tank 20a. The partition plate 23a may be manufactured in any form as long as it can control the flow path of the cathode electrolyte. For example, the partition plate 23a may have a plate shape. In addition, the partition plate 23a is preferably formed in a horizontal direction (see FIG. 2) to smoothly flow the cathode electrolyte, and may be formed in plurality. At this time, the partition plate 23a is formed in the horizontal direction so that the flow path is longest (zigzag flow) while the flow of the cathode electrolyte is smooth, and the concentration gradient of the cathode electrolyte is increased. Silver is preferably coupled to opposite sides of the first cathode electrolyte tank 20a with respect to the longitudinal section of the first cathode electrolyte tank 20a (see FIG. 2).

The second cathode electrolyte tank 20b is structurally identical to the first cathode electrolyte tank 20a. Therefore, in the overlapping part mentioned above, the description is abbreviate | omitted and the part which was not demonstrated above, such as the connection relationship of the 1st negative electrode electrolyte tank 20a and the 2nd negative electrode electrolyte tank 20b, is demonstrated.

The first cathode electrolyte tank 20a and the second cathode electrolyte tank 20b may be connected to the connection pipe 26 so that the cathode electrolyte contained therein may move in both directions. In addition, the first negative electrolyte tank 20a and the second negative electrolyte tank 20b are respectively provided with the electrolyte inlets 21a and 21b so that the negative electrolyte flowing into the tank through the electrolyte inlets 21a and 21b is introduced into the lower end of the tank. And extension pipes 27a and 27b connected to each other. At this time, the negative electrolyte flowing into the lower portion is moved to the adjacent tank through the connection pipe 26 (for example, after flowing into the first negative electrolyte tank 20a, and then flows out to the second negative electrolyte tank 20b). When the negative electrode electrolyte has the longest movement path to form a large concentration gradient, the connecting pipe 26 may include partition plates provided in the first negative electrode electrolyte tank 20a and the second negative electrode electrolyte tank 20a. In the case of plural, it is preferable to be located at a point higher than (23a, 23b) means the highest partition plate.

The stack unit 30 may include one or a plurality of battery cells. The battery cell may include a positive electrode 32 and a negative electrode 33 positioned with the ion exchange membrane 31 and the ion exchange membrane 31 interposed therebetween. The anode 32 and the cathode 33 may be made of a variety of known materials, for example, may be made of graphite. The ion exchange membrane 31 preferably has high selectivity for ions, small electrical resistance, small diffusion coefficients of solutes and solvents, chemical stability, excellent mechanical strength, and economical efficiency. In general, Nafion (Dupnot), CMV, AMV, DMV (Asahi Glass) and the like can be used. In the case of vanadium-based redox flow batteries, however, an active material mixed with a transition metal element and a strong acid is used as an electrolyte. Therefore, a membrane having high acid resistance, oxidation resistance, and permeability is required. When applying a Nafion membrane to a vanadium battery, Due to the permeation, the energy efficiency is low, and in the case of the CMV membrane, the lifespan characteristics are poor. Therefore, in order to compensate for these disadvantages, an ion exchange membrane using an engineering plastic polymer having excellent mechanical properties in a strong acid atmosphere and a high temperature region may be applied. For example, polyether ether ketone (PEEK), polysulfone (PSF), and polybenzimidazole ) Can be used.

In addition, a pump for transferring the cathode electrolyte contained in the first and second anode electrolyte tanks 10a and 10b and the cathode electrolyte contained in the first and second cathode electrolyte tanks 20a and 20b to the stack unit 30, respectively ( 40a, 40b) may be further included.

3 is a view schematically showing a redox flow battery according to an embodiment of the present invention. Referring to FIG. 3, the redox flow battery according to the exemplary embodiment of the present invention may further include a controller 50 in the redox flow battery illustrated in FIG. 2. The control unit 50 is provided in the electrolyte passages connected to the first and second anode electrolyte tanks 10a and 10b and the first and second cathode electrolyte tanks 20a and 20b, respectively, to control opening and closing of the passage ( 14a, 14b, 15a, 15b, 24a, 24b, 25a, 25b) can be controlled. 4 and 5 are schematic views illustrating a charging and discharging process of the redox flow battery of FIG. 3, respectively, and the controller 50 will be described in detail with reference to FIGS. 4 and 5. Configurations other than the controller 50 have been described above, and the description thereof will be omitted.

The process of first charging the vanadium-based redox flow battery will be described with reference to FIG. 4. When charging occurs, V ⁴⁺ ions are oxidized to V ⁵⁺ ions at the anode and V ³⁺ ions are reduced to V ²⁺ ions at the cathode. The first anode electrolyte tank 10a contains a positive electrolyte rich in V ⁴⁺ ions, the second anode electrolyte tank 10b contains a positive electrolyte rich in V ⁵⁺ ions, and a first cathode electrolyte tank 20a. The negative electrode electrolyte rich in V ²⁺ ions is accommodated, and the second negative electrode electrolyte tank 20b is set to receive the negative electrode electrolyte rich in V ³⁺ ions, and the controller 50 controls the second positive electrode electrolyte tank 10b. ), The outlet valve 15b and the outlet valve 25a of the first cathode electrolyte tank 20a are closed, and the outlet valve 15a of the first anode electrolyte tank 10a and the outlet of the second cathode electrolyte tank 20b are closed. The valve 25b is opened to allow the positive electrolyte rich in V ⁴⁺ ions and the negative electrolyte rich in V ³⁺ ions to move to the stack 30. When the charging process occurs in the stack 30, the anode electrolyte and the cathode electrolyte are changed to a state in which V ⁵⁺ ions and V ²⁺ ions are rich, respectively, and the controller 50 controls the inflow valve of the first anode electrolyte tank 10a. The inlet valve 24b of the 14a and the second cathode electrolyte tank 20b is closed, and the inflow valve 14b of the second anode electrolyte tank 10b and the inflow valve 24a of the first cathode electrolyte tank 10a are closed. Open to allow the electrolyte rich in V ⁵⁺ ions and V ²⁺ ions, respectively, to flow into the second anode electrolyte tank 10b and the first cathode electrolyte tank 20a. When explaining to the positive electrolyte tanks 10a and 10b, the positive electrolyte rich in V ⁵⁺ ions flows into the second positive electrolyte tank 10b so that the first positive electrolyte tank 10a is still rich in V ⁴⁺ ions. The cathode electrolyte is accommodated, and the anode electrolyte rich in V ⁴⁺ ions may be continuously introduced into the stack 30 during the charging process. For the same reason, the negative electrode electrolyte rich in V ²⁺ ions flows into the first negative electrode electrolyte tank 20a, and the second negative electrode electrolyte tank 20b still contains the negative electrode electrolyte rich in V ³⁺ ions, and continues in the charging process. The negative electrode electrolyte rich in V ³⁺ ions may flow into the stack 30, and thus, may be charged at a lower open circuit voltage (OCV) than when using a single tank or a tank without a partition plate.

Next, a process of discharging through FIG. 5 will be described. When discharge occurs, V ⁵⁺ ions are reduced to V ⁴⁺ ions at the anode and V ²⁺ ions are oxidized to V ³⁺ ions at the cathode. The first anode electrolyte tank 10a contains a positive electrolyte rich in V ⁴⁺ ions, the second anode electrolyte tank 10b contains a positive electrolyte rich in V ⁵⁺ ions, and a first cathode electrolyte tank 20a. The negative electrode electrolyte rich in V ²⁺ ions is accommodated, and the second negative electrode electrolyte tank 20b is set to receive the negative electrode electrolyte rich in V ³⁺ ions, and the controller 50 controls the first positive electrode electrolyte tank 10a. ), The outlet valve 15a and the outlet valve 25b of the second cathode electrolyte tank 20b are closed, and the outlet valve 15b of the second anode electrolyte tank 10b and the outlet of the first cathode electrolyte tank 20a are closed. The valve 25a is opened to allow the positive electrolyte rich in V ⁵⁺ ion and the negative electrolyte rich in V ²⁺ ion to move to the stack 30. When the discharge process occurs in the stack 30, the anolyte and the catholyte are changed to a state rich in V ⁴⁺ ions and V ³⁺ ions, respectively, and the controller 50 controls the inflow valve of the second anode electrolyte tank 10b. 14b and the inflow valve 24a of the 1st cathode electrolyte tank 20a are closed, and the inflow valve 14a of the 1st anode electrolyte tank 10a and the inflow valve 24b of the 2nd cathode electrolyte tank 20b are closed. Open to allow the electrolyte rich in V ⁴⁺ ions and V ³⁺ ions, respectively, to flow into the first anode electrolyte tank 10a and the second cathode electrolyte tank 20b. If only the anode electrolyte tanks 10a and 10b are described, the anode electrolyte rich in V ⁴⁺ ions flows into the first anode electrolyte tank 10a so that the second anode electrolyte tank 10b is still rich in V ⁵⁺ ions. The positive electrolyte is accommodated, and the positive electrolyte rich in V ⁵⁺ ions may be continuously introduced into the stack 30 during the discharge process. For the same reason, the negative electrode electrolyte rich in V ³⁺ ions flows into the second negative electrode electrolyte tank 20b, and the first negative electrode electrolyte tank 20a still contains the negative electrode electrolyte rich in V ²⁺ ions, and is continuously discharged. The negative electrode electrolyte rich in V ²⁺ ions may flow into the stack unit 30, and thus, may discharge at a higher open circuit voltage (OCV) than when using a single tank or a tank without a partition plate.

As a result, it is possible to form a concentration gradient of the electrolyte solution so that the voltage at the time of charging can be used lower than the OCV of the conventional redox flow battery, and the voltage at the time of discharging can be used to delay the reaching of the voltage upper limit or the lower limit, and thus the larger It can have the effect of longer operation with power (improved battery efficiency).

Hereinafter, the configuration of the present invention and its effects through specific examples and comparative examples will be described in more detail. However, this embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

EXAMPLE

As shown in FIG. 2, two positive electrode electrolyte tanks and two negative electrode electrolyte tanks were connected to each other, and a vanadium-based redox flow battery in which a partition plate was installed in the tank was prepared.

[Comparative Example]

A vanadium-based redox flow battery consisting of a single tank consisting of a positive electrode electrolyte tank and a negative electrode electrolyte tank without a partition plate was prepared.

Experimental Example

Voltage and state of charge (SoC) were measured while charging and discharging with respect to the example in which the concentration gradient of the electrolyte was formed and the comparative example in which the concentration gradient of the electrolyte was not formed, and the overpotential was measured. Shown in 7 and 8 show enlarged charge end points and discharge end points, respectively. 6 to 8, OCV (Open Circuit Voltage) shows the voltage of the battery when there is no load, and CCV (Closed Circuit Voltage) shows the voltage of the battery under the load.

In the redox flow battery, an upper limit or a lower limit of a voltage is set to prevent overcharging or overdischarging, and when the voltage reaches the limit, the current decreases so that charging or discharging is terminated. The overpotential is reduced, and accordingly, the DoD (Depth of Discharge) is increased. That is, in the comparative example, the DoD was 86% (7-93%), whereas in the example, the DoD was increased to 92% (4-96%).

In addition, as the overpotential decreases, the voltage at the time of charging decreases and the voltage at the time of discharging increases, thereby increasing the voltage efficiency (discharge voltage / charging voltage) of the battery, and the energy efficiency of the battery (voltage efficiency * coulombic efficiency). ) Increased. In the comparative example, assuming that the voltage efficiency is 88% and the coulombic efficiency is 95%, the energy efficiency of the battery is 83%. On the contrary, in the embodiment, the overpotential decreases by 30%, and the voltage efficiency rises to 91%. Energy efficiency will increase to 86%.

In the present specification, only a few examples of various embodiments performed by the present inventors are described, but the technical idea of the present invention is not limited thereto, but may be variously modified and implemented by those skilled in the art.

10: anode electrolyte tank
10a: first anode electrolyte tank
10b: second anode electrolyte tank
11, 11a, 11b: electrolyte inlet
12, 12a, 12b: electrolyte outlet
13, 13a, 13b: partition plate
14, 14a, 14b: electrolyte inlet valve
15, 15a, 15b: electrolyte outlet valve
16: connector
17a, 17b: extension pipe
20: cathodic electrolyte tank
20a: first cathode electrolyte tank
20b: second cathode electrolyte tank
21, 21a, 21b: electrolyte inlet
22, 22a, 22b: electrolyte outlet
23, 23a, 23b: partition plate
24, 24a, 24b: electrolyte inlet valve
25, 25a, 25b: electrolyte outlet valve
26 connector
27a, 27b: extension tube
30: stack part
31: ion exchange membrane
32: anode
33: cathode
40a, 40b: pump
50: control unit

Claims (27)

An anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower end, and having a partition plate for forming a concentration gradient of the anode electrolyte contained therein;
An anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower end, and having a partition plate for forming a concentration gradient of the cathode electrolyte contained therein; And
And a stack unit configured to receive electrolyte from a cathode electrolyte tank and a cathode electrolyte tank to store and discharge electric power. The partition plate of claim 1, wherein the partition plate provided in the anode electrolyte tank includes:
Redox flow battery, characterized in that installed in the horizontal direction. The partition plate of claim 1, wherein the partition plate provided in the anode electrolyte tank includes:
A redox flow battery, characterized in that a plurality. The method of claim 3, wherein the plurality of partition plates,
Installed in the horizontal direction, the adjacent partition plate is characterized in that coupled to the opposite side of the positive electrolyte tank, redox flow battery. The partition plate of claim 1, wherein the partition plate provided in the cathode electrolyte tank is
Redox flow battery, characterized in that installed in the horizontal direction. The partition plate of claim 1, wherein the partition plate provided in the cathode electrolyte tank is
A redox flow battery, characterized in that a plurality. The method of claim 6, wherein the plurality of partition plates,
Installed in the horizontal direction, the adjacent partition plate is characterized in that coupled to the opposite side of the cathode electrolyte tank, redox flow battery. The method of claim 1, wherein the stack portion,
At least one battery cell,
The battery cell,
Ion exchange membrane;
An anode positioned with an ion exchange membrane interposed therebetween; And a negative electrode; characterized in that the redox flow battery. The method of claim 1,
And a pump for transferring the anode electrolyte contained in the anode electrolyte tank to the stack part. The method of claim 1,
A redox flow battery, comprising: a pump for transferring a cathode electrolyte contained in a cathode electrolyte tank to a stack portion. A first anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower part, and a partition plate for forming a concentration gradient of the anode electrolyte contained therein;
A second anode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower end, and a partition plate for forming a concentration gradient of the anode electrolyte contained therein;
A first cathode electrolyte tank having an electrolyte inlet at an upper end thereof, an electrolyte outlet at the bottom thereof, and a partition plate for forming a concentration gradient of the cathode electrolyte contained therein;
A second cathode electrolyte tank having an electrolyte inlet at an upper end, an electrolyte outlet at a lower part thereof, and a partition plate for forming a concentration gradient of the cathode electrolyte contained therein; And
And a stack unit configured to receive electrolyte from the first and second anode electrolyte tanks and the first and second cathode electrolyte tanks to store and discharge electric power. The partition plate of claim 11, wherein the partition plates provided in the first and second anode electrolyte tanks are provided.
Redox flow battery, characterized in that installed in the horizontal direction. The partition plate of claim 11, wherein the partition plates provided in the first and second anode electrolyte tanks are provided.
A redox flow battery, characterized in that a plurality. The method of claim 13, wherein the plurality of partition plates,
It is installed in the horizontal direction, the adjacent partition plate, characterized in that coupled to the opposite side in the first and second anode electrolyte tank, respectively, redox flow battery. The method of claim 11,
The first anode electrolyte tank and the second anode electrolyte tank, characterized in that connected to the connecting pipe which can move the anode electrolyte contained therein, the redox flow battery. The method of claim 15, wherein the connector
The redox flow battery, characterized in that located at a point higher than the partition plate provided in the first anode electrolyte tank and the second anode electrolyte tank. The method of claim 11, wherein the first positive electrode electrolyte tank and the second positive electrode electrolyte tank,
And an extension tube connected to the electrolyte inlet so that the anode electrolyte introduced into the tank is introduced into the lower end of the tank, respectively. The partition plate of claim 11, wherein the partition plates provided in the first and second cathode electrolyte tanks are provided.
Redox flow battery, characterized in that installed in the horizontal direction. The partition plate of claim 11, wherein the partition plates provided in the first and second cathode electrolyte tanks are provided.
A redox flow battery, characterized in that a plurality. The method of claim 19, wherein the plurality of partition plates,
It is installed in the horizontal direction, the adjacent partition plate, characterized in that coupled to the opposite side in the first and second cathode electrolyte tank, respectively, redox flow battery. The method of claim 11,
The first cathode electrolyte tank and the second cathode electrolyte tank is characterized in that connected to the connecting pipe which can move the cathode electrolyte contained therein, the redox flow battery. The method of claim 21, wherein the connector,
The redox flow battery, characterized in that located at a point higher than the partition plate provided in the first cathode electrolyte tank and the second cathode electrolyte tank. The method of claim 11, wherein the first cathode electrolyte tank and the second cathode electrolyte tank,
And an extension tube connected to the electrolyte inlet so that the cathode electrolyte introduced into the tank flows into the lower end of the tank, respectively. The method of claim 11, wherein the stack portion,
At least one battery cell,
The battery cell,
Ion exchange membrane;
An anode positioned with an ion exchange membrane interposed therebetween; And a negative electrode; characterized in that the redox flow battery. The method of claim 11,
And a pump which transfers the positive electrolyte contained in the first and second positive electrolyte solutions to the stack. The method of claim 11,
And a pump configured to transfer the negative electrode electrolytes contained in the first and second negative electrode electrolyte tanks to the stack part. The method of claim 11,
And a control unit installed in an electrolyte passage connected to the first and second anode electrolyte tanks and the first and second cathode electrolyte tanks, respectively, to control a valve for controlling opening and closing of the passage. .

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