KR102063431B1 - A oxidation-reduction flow battery - Google Patents

Abstract

The present invention stack portion; An electrolyte tank unit for supplying an electrolyte solution to the stack unit or recovering an electrolyte solution from the stack unit; An electrolyte supply line for supplying an electrolyte solution to the stack part from the electrolyte tank part; An electrolyte recovery line for recovering the electrolyte solution discharged from the stack unit to the electrolyte tank unit; A temperature control unit for controlling the temperature of the electrolyte tank unit; And a redox flow battery including a concentration measuring unit connected to the electrolyte supply line and a control method thereof, wherein the optimum discharge current is determined in consideration of the temperature factor and the concentration factor of the electrolyte solution, The redox flow battery may be discharged according to an optimum discharge current value and an optimum output voltage by determining an output voltage of the battery.

Description

Redox flow battery and its control method {A oxidation-reduction flow battery}

The present invention relates to a redox flow battery and a control method thereof, and more particularly, to a redox flow battery and a control method thereof capable of controlling a battery at an optimum efficiency according to electrolyte concentration and temperature.

Renewable energy, such as solar and wind power, depends on highly volatile natural energy, making it difficult to cope with power variability and making it difficult to secure stability of power supply. Therefore, a large capacity power storage technology is required to accommodate the fluctuations of renewable energy and to smoothly supply power and efficiently utilize power generation facilities.

Oxidation-reduction (redox) flow cells are secondary batteries for high-capacity power storage, and have low maintenance costs, operate at room temperature, and can independently design capacity and output.

The redox flow battery includes a stack in which a plurality of cells are stacked, an electrolyte tank for storing an anode electrolyte and a cathode electrolyte, and a circulation device such as a pump for supplying and discharging the anode electrolyte and the cathode electrolyte to the stack. Include.

The positive and negative electrolytes circulate inside the stack to cause an oxidation / reduction reaction.

On the other hand, in general, the redox flow battery has a different efficiency and lifespan of the system depending on the active species concentration of the electrolyte.

More specifically, the energy storage system to which the redox flow battery is applied is generally a plant equipment installed outdoors, and the temperature range of the electrolyte storage tank is changed according to seasons and weather, and the temperature change in the system is electrochemically It affects the reaction rate, and the reaction rate increases with increasing temperature.

However, at a high temperature of the electrolyte, a change in concentration of the electrolyte occurs due to precipitation of the electrolyte, and the change in the concentration of the electrolyte causes a decrease in performance of the system.

Therefore, in order to maintain a constant concentration of the electrolyte, it may be considered to maintain a constant temperature of the redox flow battery, it is very difficult to maintain a constant temperature of the electrolyte in the electrolyte reservoir according to the season and weather. to be.

In particular, even if the temperature of the electrolyte in the electrolyte storage tank is kept constant, it is very difficult to keep the temperature of the electrolyte solution discharged from the electrolyte storage tank continuously constant.

That is, the electrolyte discharged from the electrolyte reservoir is supplied to the stack through the electrolyte supply line, and it is very difficult to keep the temperature of the electrolyte solution in the electrolyte supply line and the stack constant.

In addition, as described above, in the concentration of the electrolyte, the concentration of the electrolyte is also changed by the precipitation phenomenon of the electrolyte at a high temperature of the electrolyte, but the concentration changes continuously due to the continuous use of the redox flow battery. It is difficult to keep the concentration of the electrolyte constant only by keeping the temperature of the electrolyte constant.

In this situation, when the redox flow battery, which is a secondary battery, is discharged with a constant current and a constant voltage, when discharged with an excessive current and an excessive voltage, deterioration of the flow battery occurs, and secondary by deterioration. The battery becomes difficult to use.

Therefore, in the present invention, rather than maintaining the temperature and concentration of the electrolyte solution, rather than considering the temperature factor and concentration factor of the electrolyte solution in the current state, the oxidation-reduction flow battery at the optimum discharge current and the optimum output voltage By discharging, it is intended to prevent deterioration of the flow battery cell.

Korea Patent Publication 10-2013-0038234

The problem to be solved by the present invention, in consideration of the temperature factor of the electrolyte and the concentration factor of the electrolyte solution, to provide an oxidation-reduction flow battery and a control method thereof for controlling the redox flow battery with optimum efficiency. have.

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

The present invention in order to solve the above-mentioned problem is the stack; An electrolyte tank unit for supplying an electrolyte solution to the stack unit or recovering an electrolyte solution from the stack unit; An electrolyte supply line for supplying an electrolyte solution to the stack part from the electrolyte tank part; An electrolyte recovery line for recovering the electrolyte solution discharged from the stack unit to the electrolyte tank unit; A temperature control unit for controlling the temperature of the electrolyte tank unit; And it provides a redox flow battery comprising a concentration measuring unit connected to the electrolyte supply line.

In addition, the present invention, the electrolyte tank unit, a positive electrode electrolyte supply tank for supplying a positive electrolyte solution to the stack portion; A cathode electrolyte supply tank for supplying a cathode electrolyte to the stack part; A cathode electrolyte recovery tank for recovering the anode electrolyte discharged from the stack unit; And a cathode electrolyte recovery tank for recovering the cathode electrolyte discharged from the stack part, wherein the electrolyte tank part includes a main tank, and the main tank divides the anode electrolyte supply tank and the anode electrolyte recovery tank. 1 bulkhead; A second partition partitioning the cathode electrolyte supply tank and the cathode electrolyte recovery tank; And a third partition wall that partitions the cathode electrolyte supply tank and the anode electrolyte supply tank.

In addition, the present invention, the temperature control unit controls the temperature of the anode electrolyte of the cathode electrolyte supply tank and the cathode electrolyte of the cathode electrolyte supply tank, the temperature control unit, the cathode electrolyte of the anode electrolyte supply tank and the cathode electrolyte supply A temperature sensor for measuring the temperature of the cathode electrolyte of the tank; A fluid supply source supplying a fluid for cooling or heating the cathode electrolyte and the cathode electrolyte; And it provides a redox flow cell comprising a fluid circulation line for circulating the fluid supplied from the fluid source.

In addition, the present invention is the fluid circulation line, the first partition, the second partition, the third partition, the main tank region located in the lower portion of the positive electrolyte supply tank and the lower portion of the cathode electrolyte supply tank It provides a redox flow battery installed in the main tank area.

In addition, the present invention, the electrolyte supply line, the anode electrolyte supply line for supplying a cathode electrolyte solution to the stack portion from the anode electrolyte supply tank; And a cathode electrolyte supply line for supplying a cathode electrolyte solution to the stack part from the cathode electrolyte supply tank.

In addition, the present invention, the concentration measuring unit, the first chamber is connected to the anode electrolyte supply line; A second chamber connected to the cathode electrolyte supply line; A membrane located between the first chamber and the second chamber; A first terminal plate positioned at the first chamber side; A second terminal plate positioned on the second chamber side; And a power supply unit for applying power to the first terminal plate and the second terminal plate.

In addition, the present invention, the concentration measuring unit is connected to one side of the first chamber, the cathode electrolyte inflow channel through which the anode electrolyte flows; A positive electrolyte discharge channel connected to the other side of the first chamber and discharging the positive electrolyte; A cathode electrolyte inflow channel connected to one side of the second chamber and into which the cathode electrolyte is introduced; And a cathode electrolyte discharge channel connected to the other side of the second chamber, through which the cathode electrolyte is discharged, and wherein the concentration measurement unit comprises: an anode electrolyte auxiliary supply line connecting the anode electrolyte inflow channel and the anode electrolyte supply line; An anode electrolyte auxiliary discharge line connecting the cathode electrolyte discharge channel and the anode electrolyte supply line; A cathode electrolyte auxiliary supply line connecting the cathode electrolyte inflow channel and the cathode electrolyte supply line; And a cathode electrolyte auxiliary discharge line connecting the cathode electrolyte discharge channel and the cathode electrolyte supply line.

In addition, the present invention is the stack portion includes at least one redox flow battery cell, wherein the redox flow battery cell is an ion exchange membrane membrane, the first electrode portion and the membrane positioned between the first It provides a redox flow battery comprising a two-electrode portion.

In addition, the present invention comprises the steps of measuring the open circuit voltage of the electrolyte supplied to the redox flow battery cell; Selecting an optimal current load according to the open circuit voltage and the temperature of the electrolyte; Measuring a state of charge (SOC) of the redox flow battery cell; And determining an output voltage of the redox flow battery cell according to the state of charge (SOC) and the optimum current load value.

In addition, the present invention, the redox flow battery, the stack unit including at least one of the redox flow battery cell; An electrolyte tank unit for supplying an electrolyte solution to the stack unit or recovering an electrolyte solution from the stack unit; An electrolyte supply line for supplying an electrolyte solution to the stack part from the electrolyte tank part; An electrolyte recovery line for recovering the electrolyte solution discharged from the stack unit to the electrolyte tank unit; A temperature control unit for controlling the temperature of the electrolyte tank unit; And a concentration measuring unit connected to the electrolyte supply line, and measuring the open circuit voltage through the concentration measuring unit and measuring a temperature of the electrolyte through the temperature control unit. .

In addition, in the present invention, the optimal current load value is a discharge current value in the discharge mode of the redox flow battery cell, and the output voltage is the discharge current in the discharge mode of the redox flow battery cell. It provides a control method of a redox flow battery, characterized in that the cell voltage during.

According to the present invention as described above, in consideration of the temperature factor and concentration factor of the electrolyte in the current state, the optimum discharge current is determined, and through this, the optimum output voltage is determined, thereby the optimum discharge current value and The redox flow battery can be discharged according to an optimum output voltage.

In addition, deterioration of the redox flow battery cell can be prevented by discharging the redox flow battery according to an optimum discharge current value and an optimum output voltage.

1 is a schematic diagram illustrating a redox flow battery according to the present invention.
2 is a schematic perspective view showing a redox flow battery cell according to the present invention.
3 is a schematic cross-sectional view showing a concentration measuring unit according to the present invention.
4 is a schematic flowchart illustrating a control method of a redox flow battery according to the present invention.
5 is a graph showing an example of an optimum current load according to the open circuit voltage and temperature of the electrolyte.
6 is a graph showing an example of the cell voltage according to the state of charge of the cell.
7 is a graph showing an example of the cell voltage according to the state of charge and discharge current of the cell.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Regardless of the drawings, the same reference numbers refer to the same components, and “and / or” includes each and every combination of one or more of the items mentioned.

Although the first, second, etc. are used to describe various components, these components are of course not limited by these terms. These terms are only used to distinguish one component from another. Therefore, of course, the first component mentioned below may be a second component within the technical spirit of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and / or "comprising" does not exclude the presence or addition of one or more other components in addition to the mentioned components.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

The spatially relative terms " below ", " beneath ", " lower ", " above ", " upper " It can be used to easily describe a component's correlation with other components. Spatially relative terms are to be understood as including terms in different directions of components in use or operation in addition to the directions shown in the figures. For example, when flipping a component shown in the drawing, a component described as "below" or "beneath" of another component may be placed "above" the other component. Can be. Thus, the exemplary term "below" can encompass both an orientation of above and below. The components can be oriented in other directions as well, so that spatially relative terms can be interpreted according to the orientation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating a redox flow battery according to the present invention.

Referring to FIG. 1, the redox flow battery 10 according to the present invention includes a stack 20; An electrolyte tank part 30 for supplying an electrolyte solution to the stack part or recovering an electrolyte solution from the stack part; An electrolyte supply line 50 for supplying an electrolyte solution from the electrolyte tank part 30 to the stack part 20; And an electrolyte recovery line 60 for recovering the electrolyte solution discharged from the stack unit 20 to the electrolyte tank unit 30.

The stack unit 20 is composed of a plurality of redox flow battery cells (hereinafter, referred to as "battery cells"), in which the drawing shows that five redox flow battery cells are stacked. However, alternatively, the redox flow battery cells may be at least one or more, and thus, the number of the redox flow battery cells is not limited in the present invention.

Hereinafter, the redox flow battery cell according to the present invention will be described in more detail. However, the redox flow battery cell according to the present invention to be described below corresponds to one example, and is a redox flow battery in the present invention. It is not limited to the structure of the cell.

2 is a schematic perspective view showing a redox flow battery cell according to the present invention.

That is, the redox flow battery cell of FIG. 2 illustrates one redox flow battery cell of the plurality of battery cells in the stack 20 of FIG. 1 described above.

Referring to FIG. 2, the redox flow battery cell 100 according to the present invention (hereinafter, referred to as a “cell cell”) includes a membrane 110 that is an ion exchange membrane and a membrane positioned between the membrane 110. The first electrode part 120 and the second electrode part 130 are included.

The first electrode part 120 includes a first porous electrode 122 and a first flow frame 121 for supporting the first porous electrode 122, and the second electrode part 130 includes a second electrode. And a second flow frame 131 supporting the porous electrode 132 and the second porous electrode 132.

In addition, the first electrode part 120 includes a first outer frame part 140 positioned outside the first flow frame 121, and the second electrode part 120 includes the second flow frame. And a second outer frame part 150 positioned outside the 131.

In this case, although not shown in the drawing, the first electrode part 120 may include an anode electrode (not shown) positioned between the first flow frame 121 and the first outer frame part 140. In addition, the second electrode unit 130 may include a cathode electrode (not shown) positioned between the second flow frame 131 and the second outer frame unit 150.

In this case, the first flow frame 121 may be an anode flow frame, and the second flow frame 131 may be a cathode flow frame.

In this case, the first outer frame portion 140 may be an anode outer frame portion, and the second outer frame portion 140 may be a cathode outer frame portion.

The flow frames 121 and 131 may be made of polypropylene (PP), polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polystyrene (PS), and PET (polypropylene). It may be any one material selected from polyethylene terephthalate), PVC (polyvinyl chloride) and Epoxy, but the type of the flow frame (121, 131) is not limited in the present invention.

In addition, the first porous electrode 122 and the second porous electrode 132 may be made of carbon felt, the anode electrode and the cathode electrode may be a graphite material, but, in the present invention, their materials It is not limiting.

In addition, the first outer frame part 140 may include a first outer frame 141; The first electrolyte solution inlet 142a is located at one side of the first outer frame 141 and the first electrolyte solution outlet 142b is located at the other side of the first outer frame 141.

The first electrolyte may be a positive electrolyte, that is, the positive electrolyte may be injected into the first electrolyte inlet 142a and discharged to the first electrolyte outlet 142b.

In addition, the second outer frame part 150 may include a second outer frame 151; And a second electrolyte solution inlet 152a located at one side of the second outer frame 151 and a second electrolyte solution outlet 152b located at the other side of the second outer frame 151.

The second electrolyte may be a negative electrolyte, that is, the negative electrolyte may be injected into the second electrolyte inlet 152a and discharged into the second electrolyte outlet 152b.

Subsequently, referring to FIG. 2, as described above, the battery cell 100 according to the present invention includes a membrane 110, which is an ion exchange membrane, and a first electrode part 120 positioned between the membrane 110. ) And a second electrode part 130, and the first electrode part 120 is disposed on the first flow frame 121 and the other side of the membrane 110 located at one side of the membrane 110. It may include a second flow frame 131 located.

In this case, the first flow frame 121 may be an anode flow frame, and the second flow frame 131 may be a cathode flow frame.

As shown in FIG. 2, the first flow frame 121 may include a first electrolyte first moving part 123a and the first flow frame 121 positioned on one side of the first flow frame 121. It includes a first electrolyte solution second moving part 123b located on the other side of the.

In this case, the first electrolyte may be a positive electrolyte.

That is, in the present invention, the positive electrolyte is injected into the first electrolyte injection hole 142a, and is transferred to the first porous electrode 122 through the first electrolyte first moving part 123a. The positive electrolyte flowed from the porous electrode 122 is transferred to the first electrolyte outlet 142b through the first electrolyte second mover 123b, and finally, the positive electrolyte is discharged from the first electrolyte outlet 142b. Can be discharged through).

In addition, as shown in FIG. 2, the second flow frame 131 may include a second electrolyte solution first moving part 133a and the second flow frame located on one side of the second flow frame 131. And a second electrolyte solution second moving part 133b located on the other side of 131.

In this case, the first electrolyte may be a cathode electrolyte.

That is, in the present invention, the cathode electrolyte is injected into the second electrolyte injection hole 152a, and is transferred to the second porous electrode 132 through the second electrolyte first moving part 133a. The cathode electrolyte flowed from the porous electrode 132 is transferred to the second electrolyte outlet 152b through the second electrolyte second mover 133b, and finally the cathode electrolyte is discharged from the second electrolyte outlet 152b. Can be discharged through).

In this case, when the anode electrolyte of the redox flow battery 10 according to the present invention does not contain titanium ions, the cathode electrolyte contains at least one of manganese ions of divalent manganese ions and trivalent manganese ions. When titanium ion is included in a form and a positive electrolyte solution, the form containing at least 1 sort (s) of manganese ion and tetravalent titanium ion among bivalent manganese ion and trivalent manganese ion is mentioned.

In addition, the cathode electrolyte of the redox flow battery 10 according to the present invention is a form containing a single kind of metal ions among titanium ions, vanadium ions, chromium ions, zinc ions and tin ions, and plural kinds thereof listed. It can be made into the form containing the metal ion of.

However, in the present invention, the type of metal ions included in the cathode electrolyte and the cathode electrolyte is not limited.

At this time, in the present invention, the solvent in the positive electrolyte solution and the negative electrode electrolyte solution is H ₂ SO ₄ , K ₂ SO ₄ , Na ₂ SO ₄ , H ₃ PO ₄ , H ₄ P ₂ O ₇ , K ₂ PO ₄ , Na _It may be at least one aqueous solvent selected from ₃ PO ₄ , K ₃ PO ₄ , HNO ₃ , KNO _3, and NaNO ₃ , and accordingly, in the present invention, the positive electrolyte solution and the negative electrode electrolyte solution may correspond to an aqueous electrolyte solution. .

Alternatively, the solvent in the positive electrolyte solution and the negative electrode electrolyte solution is dimethyl acetamide, diethyl carbonate, dimethyl carbonate, acetonitrile, gamma-bupyrolactone, propylene carbonate, ethylene carbonate, N-methyl-2-pyrroli It may be at least one non-aqueous solvent selected from the group consisting of don, fluoroethylene carbonate, and NN-dimethylacetamide, and accordingly, in the present invention, the positive electrolyte solution and the negative electrolyte solution may correspond to the non-aqueous electrolyte solution. have.

However, in the present invention, the type of the cathode electrolyte and the cathode electrolyte is not limited.

Subsequently, referring to FIG. 1, the electrolyte tank part 30 includes a cathode electrolyte supply tank 31 a for supplying an anode electrolyte solution to the stack part 20; And a cathode electrolyte supply tank 32a for supplying a cathode electrolyte to the stack 20, and a cathode electrolyte recovery tank 31b for recovering the cathode electrolyte discharged from the stack 20. A cathode electrolyte recovery tank 31b for recovering the cathode electrolyte discharged from the stack 20 is included.

That is, as shown in the figure, the electrolyte tank unit 30 includes a main tank 41, the main tank 41 is the positive electrolyte supply tank 31a and the positive electrolyte recovery tank 31b. A first partition 33 partitioning the wall; A second partition 34 partitioning the cathode electrolyte supply tank 32a and the cathode electrolyte recovery tank 31b; And a third partition wall 35 partitioning the anode electrolyte supply tank 31a and the cathode electrolyte supply tank 32a, and thus, may be partitioned into four spaces. The positive electrolyte recovery tank 31b and the positive electrolyte supply tank 31a; The anode electrolyte supply tank 32a and the cathode electrolyte recovery tank 31b may be respectively partitioned.

In addition, the electrolyte tank unit 30 includes a cathode electrolyte transfer unit 36 for supplying or resupplying the anode electrolyte of the cathode electrolyte recovery tank 31b to the anode electrolyte supply tank 31a. The transfer part 36 includes a positive electrolyte transfer line 36a and a positive electrolyte transfer pump 36b.

In addition, the electrolyte tank unit 30 includes a cathode electrolyte transfer unit 37 for supplying or resupplying the anode electrolyte of the anode electrolyte recovery tank 32b to the cathode electrolyte supply tank 32a. The transfer part 37 includes a negative electrolyte transfer line 37a and a negative electrolyte transfer pump 37b.

Subsequently, referring to FIG. 1, an electrolyte supply line 50 for supplying an electrolyte solution from the electrolyte tank part 30 to the stack part 20 is connected to the stack part (a) from the anode electrolyte supply tank 31a. 20, a cathode electrolyte supply line 50a for supplying an anode electrolyte solution to the anode electrolyte solution, and a cathode electrolyte supply line 50b for supplying the cathode electrolyte solution to the stack 20 from the cathode electrolyte supply tank 32a.

In this case, supplying the anode electrolyte to the stack 20 through the cathode electrolyte supply line 50a from the anode electrolyte supply tank 31a may be supplied by the anode electrolyte supply pump 51a. Supplying the cathode electrolyte solution to the stack 20 through the cathode electrolyte supply line 50b from the cathode electrolyte supply tank 32a may be supplied by the cathode electrolyte supply pump 51b.

In addition, the electrolyte recovery line 60 for recovering the electrolyte solution discharged from the stack 20 to the electrolyte tank unit 30, the anode electrolyte is discharged, as in the redox flow battery cell of FIG. The first electrolyte discharge port 142b, that is, the cathode electrolyte recovery line 60a and the cathode electrolyte for recovering the anode electrolyte discharged from the anode electrolyte discharge port of the stack 20 to the cathode electrolyte recovery tank 31b are discharged. And a cathode electrolyte recovery line 60b for recovering the anode electrolyte discharged from the cathode electrolyte outlet of the second electrolyte solution outlet 152b, that is, the stack 20 to the cathode electrolyte recovery tank 32b.

At this time, the recovery of the positive electrolyte from the positive electrolyte discharge port of the stack portion 20 to the positive electrolyte recovery tank 31b through the positive electrolyte recovery line 60a may be recovered by the positive electrolyte recovery pump 61a. In addition, recovering the negative electrolyte from the negative electrolyte discharge port of the stack 20 to the negative electrolyte recovery tank 32b through the negative electrolyte recovery line 60b may be recovered by the negative electrolyte recovery pump 61b. have.

Subsequently, referring to FIG. 1, the redox flow battery 10 according to the present invention includes a temperature control unit 40 for controlling the temperature of the electrolyte tank unit 30.

More specifically, the temperature controller 40 may control the temperature of the cathode electrolyte of the cathode electrolyte supply tank 31a and the cathode electrolyte of the anode electrolyte supply tank 32a.

The temperature control part 40 includes a temperature sensor (not shown) for measuring the temperature of the anode electrolyte of the cathode electrolyte supply tank 31a and the cathode electrolyte of the cathode electrolyte supply tank 32a; It may include a fluid supply source (not shown) for supplying a fluid for cooling or heating the cathode electrolyte and the cathode electrolyte, and may also include a fluid circulation line for circulating the fluid supplied from the fluid supply. .

At this time, the fluid circulation line, as shown in Figure 1, the first partition 33 for partitioning the positive electrolyte supply tank 31a and the positive electrolyte recovery tank 31b; A second partition 34 partitioning the cathode electrolyte supply tank 32a and the cathode electrolyte recovery tank 31b; And a third partition wall 35 partitioning the anode electrolyte supply tank 31a and the cathode electrolyte supply tank 32a, and in addition, below the anode electrolyte supply tank 31a. Located main tank area; And a main tank area positioned below the cathode electrolyte supply tank 32a.

However, the present invention does not limit the installation area of the fluid circulation line.

Subsequently, referring to FIG. 1, the redox flow battery 10 according to the present invention includes an electrolyte supply line 50 for supplying an electrolyte solution from the electrolyte tank part 30 to the stack part 20. It includes a concentration measuring unit 200 is connected.

Hereinafter, the concentration measuring unit according to the present invention will be described in more detail.

3 is a schematic cross-sectional view showing a concentration measuring unit according to the present invention.

As described above, the electrolyte supply line 50 includes a cathode electrolyte supply line 50a and a cathode electrolyte supply tank for supplying anode electrolyte from the cathode electrolyte supply tank 31a to the stack 20. A cathode electrolyte supply line 50b for supplying an anode electrolyte solution to the stack unit 20 from 32a) is included.

At this time, referring to Figure 3, the concentration measuring unit 200 according to the present invention, the first chamber 210 is connected to the anode electrolyte supply line (50a); A second chamber 220 connected to the cathode electrolyte supply line 50b; The membrane 230 is positioned between the first chamber 210 and the second chamber 220.

Each of the first chamber 210 and the second chamber 220 may be substantially occupied by a porous, conductive material such as carbon or graphite felt material, and the membrane 230 may be a cation exchange membrane or an anion exchange membrane. It may be an ion selective membrane such as.

Accordingly, the cathode electrolyte flows into the first chamber 210 from the cathode electrolyte supply line 50a, the cathode electrolyte flows into the second chamber 220 from the cathode electrolyte supply line 50b, and the membrane Since 126 serves as an ion exchange membrane, the concentration measurement unit 200 according to the present invention may be understood as a test cell having the same structure as the redox flow battery cell of FIG. 2 as described above.

At this time, the concentration measuring unit 200 according to the present invention is connected to one side of the first chamber 210, the anode electrolyte inflow channel 214 and the other side of the first chamber 210, the anode electrolyte is introduced A cathode electrolyte inlet channel 215 connected to one side of the second chamber 220 and connected to one side of the second chamber 220, and a cathode electrolyte inflow channel 224 and a second chamber in which a cathode electrolyte is introduced; It is connected to the other side of the 220, and includes a cathode electrolyte discharge channel 225 through which the cathode electrolyte is discharged.

In addition, the concentration measuring unit 200 according to the present invention includes a cathode electrolyte auxiliary supply line 211 connecting the cathode electrolyte inflow channel 214 and the anode electrolyte supply line 50a, and discharge the anode electrolyte. And a cathode electrolyte auxiliary discharge line 212 connecting the channel 215 and the anode electrolyte supply line 50a, and further connecting the cathode electrolyte inflow channel 224 and the cathode electrolyte supply line 50b. It includes a cathode electrolyte auxiliary supply line 221, and comprises a cathode electrolyte auxiliary discharge line 222 connecting the cathode electrolyte discharge channel 225 and the cathode electrolyte supply line (50b).

That is, the anode electrolyte flowing into the anode electrolyte auxiliary supply line 211 from the cathode electrolyte supply line 50a flows into the first chamber 210 through the anode electrolyte inflow channel 214, and The cathode electrolyte introduced into the first chamber 210 may be introduced into the anode electrolyte auxiliary discharge line 212 through the anode electrolyte discharge channel 215 and finally discharged into the cathode electrolyte supply line 50a. .

In addition, the negative electrode electrolyte introduced into the negative electrode electrolyte supply line 221 from the negative electrode electrolyte supply line 50b is introduced into the second chamber 220 through the negative electrode electrolyte inflow channel 224. The cathode electrolyte introduced into the two chambers 220 may be introduced into the anode electrolyte auxiliary discharge line 222 through the cathode electrolyte discharge channel 225 and finally discharged to the cathode electrolyte supply line 50b. .

In this case, the introduction of the positive electrolyte into the positive electrolyte auxiliary supply line 211 from the positive electrolyte supply line 50a may be controlled through a first valve 213, and may be controlled from the negative electrolyte supply line 50b. The introduction of the negative electrolyte into the negative electrolyte auxiliary supply line 221 may be controlled through the second valve 223.

In addition, the concentration measuring unit 200 according to the present invention, the first terminal plate 216 located on the first chamber 210 side and the second terminal plate 217 located on the second chamber 220 side. And a power supply unit 240 for applying power to the first terminal plate 216 and the second terminal plate 217.

As described above, the present invention includes a concentration measuring unit 200 connected to the electrolyte supply line 50, and through the concentration measuring unit 200 to determine the open circuit voltage (OCV, Open circuit voltage) of the electrolyte It can be measured.

Measuring the open circuit voltage (OCV, Open Circuit Voltage) of the electrolyte through the concentration measuring unit 200, the cathode electrolyte flows into the first chamber 210, the cathode electrolyte into the second chamber 210 When the power is applied to the power supply unit 240 in the state of inflow, a potential difference between the positive electrode (first chamber side) and the negative electrode (second chamber side) is generated according to the oxidation / reduction reaction, and is opened through the potential difference. Open circuit voltage (OCV) can be measured.

Subsequently, referring to FIG. 1, the redox flow battery 10 according to the present invention may include a main controller 70 for controlling the redox flow battery, and the main controller 70 may include: In addition, the temperature control unit 40 may be controlled, or information on the open circuit voltage measured by the concentration measuring unit 200 may be collected.

In addition, as described below, the main controller 70 may select an optimal current load according to the open circuit voltage and the temperature of the electrolyte, and further, the redox flow based on the optimum current load value. The output voltage of the battery cell can be determined.

As described above, in general, the redox flow battery is a temperature range of the electrolyte reservoir in accordance with the season and the weather, the temperature change in such a system affects the electrochemical reaction rate, as the temperature increases The reaction rate is increased.

However, at a high temperature of the electrolyte, a change in concentration of the electrolyte occurs due to precipitation of the electrolyte, and the change in the concentration of the electrolyte causes a decrease in performance of the system.

Therefore, in order to maintain a constant concentration of the electrolyte, it may be considered to maintain a constant temperature of the oxidation-reduction fluid battery, but this is very difficult, in particular, only by keeping the temperature of the electrolyte constant There is a difficulty in keeping the concentration of.

Accordingly, in the present invention, the problem to be solved by the present invention, in consideration of the temperature factor of the electrolyte solution and the concentration factor of the electrolyte solution, for controlling the redox flow battery with optimum efficiency, the redox flow battery and its control method To provide.

Hereinafter, a control method of a redox flow battery according to the present invention will be described.

4 is a schematic flowchart illustrating a control method of a redox flow battery according to the present invention.

Referring to FIG. 4, first, a control method of a redox flow battery according to the present invention includes measuring an open circuit voltage of an electrolyte supplied to a redox flow battery cell (S110).

Measuring the open circuit voltage of the electrolyte in the present invention, it is possible to measure the open circuit voltage (OCV, Open Circuit Voltage) of the electrolyte through the concentration measuring unit 200 of FIG.

Next, the control method of the redox flow battery according to the present invention includes the step of selecting the optimal current load according to the open circuit voltage and the temperature of the electrolyte (S120).

The temperature of the electrolyte may be measured by the temperature controller 40 of FIG. 1 described above, and furthermore, in the present invention, the temperature of the electrolyte may be adjusted through the temperature controller 40. .

Meanwhile, selecting an optimal current load according to the open circuit voltage and the temperature of the electrolyte may be performed by the main controller 70 of FIG. 1.

5 is a graph showing an example of an optimum current load according to the open circuit voltage and temperature of the electrolyte. At this time, in Figure 5, the Y axis shows the open circuit voltage, the X axis shows the optimum current load.

Referring to FIG. 5, in the situation where the temperature distribution of the electrolyte is in the range of 5 ° C. to 55 ° C., the open circuit voltage (OCV) of the electrolyte measured through the concentration measuring unit 200 of FIG. 1 described above. The optimal current load can be selected.

The optimal current load refers to the discharge current in the discharge mode of the redox flow battery cell.

That is, as shown in FIG. 5, even when the open circuit voltage (OCV) of the electrolyte is the same, when the temperature of the electrolyte is different, the optimum current load is different.

Therefore, in the present invention, by measuring the temperature of the electrolyte through the temperature control unit 40, and measuring the open circuit voltage (OCV, Open circuit voltage) of the electrolyte through the concentration measuring unit 200, In consideration of the concentration factor of the electrolyte, an optimal discharge current, that is, an optimum current load in the discharge mode of the redox flow battery cell may be selected.

Next, the control method of the redox flow battery according to the present invention includes the step of measuring the state of charge (SOC) of the redox flow battery cell (S130).

In this case, the state of charge (SOC) of the redox flow battery cell may be measured by the main controller 70 of FIG. 1.

The SOC means a ratio of the remaining capacity of the secondary battery at each time point to the remaining capacity (so-called battery capacity) of the secondary battery at the time of full charge.

At this time, as a method for measuring the SOC of the secondary battery, the SOC is generally determined from the measured value of the open circuit voltage by using an open circuit voltage-charge state characteristic (hereinafter also referred to as "OCV-SOC characteristic"). There are a method of obtaining and a method of integrating the charge / discharge current of the secondary battery and calculating the integrated value as a ratio with respect to the total capacity of the secondary battery.

In the method of integrating the charge / discharge current of the latter secondary battery, the secondary battery is deteriorated since the total capacity of the secondary battery, which is the denominator when obtaining SOC, is usually used. When the battery capacity falls, the obtained SOC includes an error.

However, in the method using the open-circuit voltage-charge state characteristic, the OCV-SOC characteristic itself does not change even when the secondary battery deteriorates and the total capacity of the secondary battery changes. It is used a lot.

Since this corresponds to the obvious matters in the art, the following detailed description will be omitted, but it is not limited to the method for measuring the state of charge of the redox flow battery cell in the present invention.

6 is a graph showing an example of the cell voltage according to the state of charge of the cell. At this time, the cell voltage in Figure 6 means the output voltage during the discharge current flows in the discharge mode of the redox flow battery cell.

As shown in FIG. 6, in general, the cell voltages are different in the range of 0% to 100% of the state of charge of the cells.

However, as shown in FIG. 6, in general, the cell voltage only considers the factors depending on the state of charge of the cell, and the temperature factor of the electrolyte and the concentration factor of the electrolyte are not considered at all.

Therefore, in the present invention, in determining the output voltage during the discharge current in the discharge mode of the redox flow battery cell, not only the state of charge of the cell, but also the temperature factor of the electrolyte and the concentration factor of the electrolyte, -To determine the optimum output voltage of the reduced flow battery cell.

Accordingly, in the control method of the redox flow battery according to the present invention, the output voltage of the redox flow battery cell is determined according to the state of charge (SOC) and the optimum current load value. It includes a step (S140).

As described above, the optimum current load value, by measuring the temperature of the electrolyte through the temperature control unit 40, by measuring the open circuit voltage (OCV, Open Circuit Voltage) of the electrolyte through the concentration measuring unit 200 The selected value corresponds to a value selected in consideration of the temperature factor of the electrolyte solution and the concentration factor of the electrolyte solution.

Therefore, in the present invention, determining the output voltage of the redox flow battery cell takes into account not only the state of charge of the redox flow battery cell, but also the temperature factor and concentration factor of the electrolyte solution provided to the redox flow battery cell. Can be determined.

7 is a graph showing an example of the cell voltage according to the state of charge and discharge current of the cell. In this case, the discharge current of the X-axis in Figure 7 is the optimum current load (Load) value selected in step S120, the value is selected in consideration of the temperature factor and the concentration factor of the electrolyte, the cell voltage on the Y-axis, The output voltage during the discharge current in the discharge mode of the redox flow battery cell. In addition, SOC 10, SOC 30, SOC 60, SOC 90 and SOC 100 means that the state of charge of the cell is 10%, 30%, 60%, 90% and 100%, respectively.

As shown in FIG. 7, for example, in the case of SOC 60, the cell voltage may be different depending on the discharge current value. More specifically, the discharge current, that is, the optimum current load value may be determined. In the case of 900 A / m 2, the cell voltage, that is, the optimum output voltage corresponds to 1 V, but when the discharge current, that is, the optimum current load value is 300 A / m 2, the cell voltage, that is, the optimum output voltage is 1.3 V. You can see that it corresponds to V.

At this time, in the graph showing an example of the cell voltage according to the state of charge of the cell of FIG. 6, when the state of charge is 60%, the output voltage of the redox flow battery cell is compared with that of the cell voltage of 1.4 V. In determining, in the case of Figure 6, only the state of charge of the redox flow battery cell was considered, but in the present invention, even if the state of charge equally 60%, by considering the temperature factor and concentration factor of the electrolyte solution, the optimum current The optimum output voltage can be determined according to the load value.

As described above, in the present invention, as described above, in the present invention, the optimum discharge current is determined in consideration of the temperature factor and the concentration factor of the electrolyte solution in the current state, rather than the viewpoint of keeping the temperature and concentration of the electrolyte solution constant. In addition, the optimum output voltage may be determined through this, and the redox flow battery may be discharged according to an optimum discharge current value and an optimum output voltage.

In addition, deterioration of the redox flow battery cell can be prevented by discharging the redox flow battery according to an optimum discharge current value and an optimum output voltage.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. You will understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (11)

A stack unit including a redox flow battery cell;
An electrolyte tank unit for supplying an electrolyte solution to the stack unit or recovering an electrolyte solution from the stack unit;
An electrolyte supply line for supplying an electrolyte solution to the stack part from the electrolyte tank part;
An electrolyte recovery line for recovering the electrolyte solution discharged from the stack unit to the electrolyte tank unit;
A temperature control unit for controlling the temperature of the electrolyte tank unit; And
It includes a concentration measuring unit connected to the electrolyte supply line,
The open circuit voltage of the electrolyte supplied to the redox flow battery cell is measured through the concentration measuring unit, and the temperature of the electrolyte is measured through the temperature control unit.
The redox flow battery, characterized in that for selecting the optimum current load of the redox flow battery cell according to the open circuit voltage and the temperature of the electrolyte. The method of claim 1,
The electrolyte tank unit, an anode electrolyte supply tank for supplying a cathode electrolyte solution to the stack portion; A cathode electrolyte supply tank for supplying a cathode electrolyte to the stack part; A cathode electrolyte recovery tank for recovering the anode electrolyte discharged from the stack unit; And a cathode electrolyte recovery tank for recovering the cathode electrolyte discharged from the stack unit.
The electrolyte tank unit includes a main tank, wherein the main tank comprises: a first partition wall partitioning the anode electrolyte supply tank and the cathode electrolyte recovery tank; A second partition partitioning the cathode electrolyte supply tank and the cathode electrolyte recovery tank; And a third partition wall partitioning the cathode electrolyte supply tank and the anode electrolyte supply tank. The method of claim 2,
The temperature control unit controls the temperature of the anode electrolyte of the cathode electrolyte supply tank and the cathode electrolyte of the cathode electrolyte supply tank,
The temperature control unit includes a temperature sensor for measuring the temperature of the anode electrolyte of the cathode electrolyte supply tank and the cathode electrolyte of the cathode electrolyte supply tank; A fluid supply source supplying a fluid for cooling or heating the cathode electrolyte and the cathode electrolyte; And a fluid circulation line for circulating the fluid supplied from the fluid source. The method of claim 3, wherein
The fluid circulation line may be installed in the first partition wall, the second partition wall, the third partition wall, a main tank area located below the anode electrolyte supply tank, and a main tank area located below the cathode electrolyte supply tank. Redox flow cell. The method of claim 2,
The electrolyte supply line, the cathode electrolyte supply line for supplying a cathode electrolyte solution to the stack portion from the anode electrolyte supply tank; And a cathode electrolyte supply line for supplying cathode electrolyte to the stack from the cathode electrolyte supply tank. The method of claim 5,
The concentration measuring unit may include a first chamber connected to the cathode electrolyte supply line; A second chamber connected to the cathode electrolyte supply line; A membrane located between the first chamber and the second chamber; A first terminal plate positioned at the first chamber side; A second terminal plate positioned on the second chamber side; And a power supply unit for applying power to the first terminal plate and the second terminal plate. The method of claim 6,
The concentration measuring unit,
A positive electrolyte inflow channel connected to one side of the first chamber and into which the positive electrolyte flows; A positive electrolyte discharge channel connected to the other side of the first chamber and discharging the positive electrolyte; A cathode electrolyte inflow channel connected to one side of the second chamber and into which the cathode electrolyte is introduced; And a cathode electrolyte discharge channel connected to the other side of the second chamber and through which the cathode electrolyte is discharged.
The concentration measuring unit, an anode electrolyte auxiliary supply line connecting the cathode electrolyte inlet channel and the anode electrolyte supply line; An anode electrolyte auxiliary discharge line connecting the cathode electrolyte discharge channel and the anode electrolyte supply line; A cathode electrolyte auxiliary supply line connecting the cathode electrolyte inflow channel and the cathode electrolyte supply line; And a cathode electrolyte auxiliary discharge line connecting the cathode electrolyte discharge channel and the cathode electrolyte supply line. The method of claim 1,
The redox flow battery cell includes a membrane which is an ion exchange membrane, and a first electrode portion and a second electrode portion positioned with the membrane interposed therebetween. Measuring an open circuit voltage of an electrolyte supplied to the redox flow battery cell;
Selecting an optimal current load of the redox flow battery cell according to the open circuit voltage and the temperature of the electrolyte solution;
Measuring a state of charge (SOC) of the redox flow battery cell; And
And determining an output voltage of the redox flow battery cell according to the state of charge (SOC) and the optimum current load value. The method of claim 9,
The redox flow battery may include a stack unit including at least one of the redox flow battery cells; An electrolyte tank unit for supplying an electrolyte solution to the stack unit or recovering an electrolyte solution from the stack unit; An electrolyte supply line for supplying an electrolyte solution to the stack part from the electrolyte tank part; An electrolyte recovery line for recovering the electrolyte solution discharged from the stack unit to the electrolyte tank unit; A temperature control unit for controlling the temperature of the electrolyte tank unit; And a concentration measurement unit connected to the electrolyte supply line,
Measuring the open circuit voltage through the concentration measuring unit, the control method of the redox flow battery for measuring the temperature of the electrolyte through the temperature control unit. The method of claim 10,
The optimum current load value is a discharge current value in the discharge mode of the redox flow battery cell, and the output voltage is a cell voltage during the discharge current in the discharge mode of the redox flow battery cell. Control method of a redox flow battery, characterized in that.

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