KR20130055855A - Redox flow battery system for storage of renewable energy - Google Patents

Abstract

PURPOSE: A redox flow battery system is provided to reduce electricity peak and to improve electricity quality. CONSTITUTION: A redox flow battery system comprises a positive electrode cell(13a) which is connected to a renewable energy generation part(100), a negative electrode cell(13b) for charging, a negative electrode cell(13d) for discharging, which is connected to load(200), and a positive electrode cell(13c). Between the positive electrode cell and the negative electrode cell, a first ion exchange film is installed. A second ion exchange film is installed between the positive electrode cell for discharging and negative electrode cell for discharging. The positive electrode cell for charging and the positive electrode cell for discharging are connected to each other through a positive electrolyte bath(11a). The negative electrode cell for discharging and the negative electrode cell for discharging are connected to each other through a negative electrolyte bath(11b). [Reference numerals] (100) Renewable energy generation; (11a) Positive electrolyte storage; (11b) Negative electrolyte storage; (13a,13c) Positive electrode cell; (13b,13d) Negative electrode cell; (200) Load; (AA,BB) Ion penetration film

Description

REDOX FLOW BATTERY SYSTEM FOR STORAGE OF RENEWABLE ENERGY}

The present invention relates to a redox flow battery system having a charging cell and a discharge cell, and more particularly, a charging cell and a consumer for storing electricity generated from a renewable energy generator in an electrolyte of a redox flow battery. The cell for discharging according to the load to be used is separated, but the electrolyte cell used in the charging cell and the discharging cell relates to a vanadium redox flow battery system for renewable energy storage. This enables the implementation of a redox flow cell system for renewable energy storage that reduces power peaks, improves power quality and minimizes system congestion.

Recently, as a countermeasure against global warming, the introduction of renewable energy such as solar power generation and wind power generation is being promoted worldwide. Since the power generation output of these renewable energies is affected by the weather, when a large amount is introduced, it is difficult to maintain a frequency or voltage and to operate a power system. As a countermeasure against this problem, a large capacity battery is installed to smooth output fluctuations, accumulate surplus power, and level loads.As a MW class large capacity power storage battery, lead-acid batteries, NaS batteries, and ultra-high capacity There is a super capacitor, a lithium secondary battery and a redox flow battery (RFB).

A secondary battery is a term that refers to a battery that can be recycled by repeatedly charging and discharging, rather than being drawn out by one use. The redox flow cell is also a kind of secondary cell.

The redox flow battery is an electrochemical charging device that stores the chemical energy of the electrolyte directly as electrical energy as a system in which an active material in the electrolyte is oxidized, reduced, and charged and discharged, unlike a conventional secondary battery.

1 is a view showing a structure of a redox flow battery system.

The basic structure of the redox battery is as shown in FIG. 12a, 12b, ion exchange membrane (membrane) 15, positive electrode cell 13a and negative electrode cell 13b, and electrodes 14a and 14b which mediate charging and discharging operations.

The electrodes 14a and 14b used in the redox flow battery are inert electrodes and have a long lifespan because they do not have a chemical reaction itself and have a property of allowing a current to flow through an electrode surface and an electrolyte.

Figure 2 is a schematic diagram showing that the power generation or discharge is conventionally configured using a redox flow battery.

Referring to FIG. 2, a charge / discharge cell including an anode cell 13a, a cathode cell 13b, and an ion exchange membrane 15 is included. According to the above configuration, the positive cell 13a and the negative cell 13b may be charged cells or discharge cells, depending on the reaction occurring.

Formula 1 and Formula 2 show reaction schemes occurring in the positive cell 13a and the negative cell 13b when the charging cell is used.

Formulas 3 and 4 show reaction schemes occurring in the positive cell 13a and the negative cell 13b when the discharge cell becomes a discharge cell.

In the case of the conventional vanadium redox flow battery system, when an external power source (not shown) is connected, an oxidation reaction occurs in the positive electrode cell 13a and a reduction reaction occurs in the negative electrode cell 13b, and the redox flow battery system as a whole is redox flow. The charging phenomenon occurs that the potential of the battery system increases.

However, such a conventional redox flow battery system has a problem in that it cannot supply power to an external load during charging.

The positive electrode and the negative electrode are not shown at this time because the positive electrode and the negative electrode do not react with the electrolyte during the charging process.

The redox flow battery system also has a structure capable of separating the battery stack (output: the positive cell 13a and the negative cell 13b) and the positive / negative electrolyte reservoir (capacity) so that the output (load) And the capacity (charging) can be freely designed and is not restricted by the installation site.

Although there is such an advantage, the configuration of the redox flow battery itself alone does not distinguish charge and discharge, as shown in FIG. 2, and thus cannot provide a stable, high-quality power source, and the cathode cell 13b or the anode cell 13a. If there is a problem with the power supply, the charging and discharging functions are simultaneously paralyzed.

Patent Document 10-2011-0119775 (redox flow battery)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The present invention provides a low-quality electricity of a power generation output of renewable energy through a method of distinguishing the positive and negative cells using the same electrolyte reservoir for charging and discharging. It is for storing renewable energy that can supply stable power and can store large amount of energy. It is possible to provide a redox flow cell system.

The present invention includes a charging positive electrode cell and a charging negative electrode cell connected to the renewable energy generation unit, a discharge negative electrode cell and a positive electrode cell connected to the load, and a first ion exchange between the charging positive electrode cell and the negative electrode cell And a second ion exchange membrane between the discharge positive electrode cell and the discharge negative electrode cell, wherein the charging positive electrode cell and the discharge positive electrode cell are connected through a positive electrode electrolyte reservoir, and the charging negative electrode cell and the The negative electrode cell for discharge provides a redox flow battery system for storing renewable energy, which is connected through a negative electrode electrolyte reservoir.

And the charging positive electrode cell and the discharging positive electrode cell may include V ^{4 +} ions and V ^{5 +} ions.

The charging cathode cell and the discharge cathode cell may include V ^{2 +} ions and V ^{3 +} ions.

The charging negative electrode cell and the charging positive electrode cell may be ones of a discharge negative electrode cell and a discharge positive electrode cell, respectively, over time.

According to the vanadium redox flow battery system for storage of renewable energy according to the present invention, charging and discharging can be simultaneously performed in one system, and power can be continuously supplied without interruption.

In addition, since it is possible to integrate a plurality of power sources into one system through a single cathode cell and a cathode cell, it is advantageous to store power from multiple generators in one reservoir.

As described above, even if the power output from the different generators is stored in one storage, it is possible to provide a high power quality by improving the problem of low power quality that may occur due to the use of renewable energy.

It can charge and discharge at the same time, but also uses the power supplied from multiple generators, so it can provide stable output and large-capacity design for places requiring power.

In the case of the present invention, since the electrolyte, the positive electrode and the negative electrode are separated from each other, the electrolyte serving as a power source can be separately moved and used for other cells. In addition, since a single charging cell is used instead of a plurality of charging cells, even if any one of the cells has a problem such as short circuit or short circuit, it can cope with charge / discharge cross use.

1 is a view showing a structure of a redox battery system.
Figure 2 is a schematic diagram showing that the power generation or discharge is conventionally configured using a redox flow battery.
Figure 3 is a schematic diagram showing the configuration of a redox flow battery system for storing renewable energy according to the present invention.
4 is a schematic diagram showing the configuration of a cell stack of a redox flow battery.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not. Wherein like reference numerals refer to like elements throughout.

The redox flow battery system for storing renewable energy according to the present invention includes a charging positive electrode cell and a charging negative electrode cell connected to a renewable energy generation unit, a discharge negative electrode cell and a positive electrode cell connected to a load, and the charging positive electrode A first ion exchange membrane is provided between the cell and the negative electrode cell, and a second ion exchange membrane is provided between the discharge positive electrode cell and the discharge negative electrode cell, and the charging positive electrode cell and the discharge positive electrode cell are formed through a positive electrode electrolyte reservoir. The charging negative electrode cell and the discharge negative electrode cell are connected through a negative electrode electrolyte reservoir.

Hereinafter, a redox flow battery system for storing renewable energy according to the present invention will be described.

Figure 3 is a schematic diagram showing the configuration of a redox flow battery system for storing renewable energy according to the present invention.

Referring to FIG. 3, the redox flow battery system for storing renewable energy includes a rechargeable negative electrode cell 13b and a rechargeable positive electrode cell 13a connected to the renewable energy generator 100. V ^{3 +} ions are reduced to V ^{2 +} ions in the charging cathode cell 13b. At this time, the potential is formed in accordance with the standard reduction potential, it is preferable that such a supply of V ^{3 +} ions are supplied from the cathode electrolyte reservoir (11b).

In addition, it is preferable that V ^{4 +} ions and V ^{5 +} ions exist in the rechargeable anode cell 13a. In the charging anode cell 13a, V ^{4 +} ions are oxidized to V ^{5 +} ions.

An ion exchange membrane (not shown) is preferably located between the charging anode cell 13a and the charging cathode cell 13b.

In addition, the redox flow battery system for storing renewable energy according to the present invention includes a discharge negative electrode cell 13d and a discharge positive electrode cell 13c connected to a load. As is V ^{2 +} ions are oxidized the discharge cathode cell (13d) and the V ^{3 +} ion, in the discharge positive electrode cell (13c) V ^{5 +} ions to be V ^{4 +} ions as the reduction potential between the cathode It can be formed to supply electrical energy to the load.

Under the above conditions, trivalent vanadium ions are present at the time of discharge, and divalent vanadium ions are present at the time of charge. When charge and discharge are repeated, bivalent vanadium ions and trivalent vanadium ions coexist.

As mentioned above, it is preferable that all the metal ion concentration used as a positive electrode active material is 0.3 M or more and 5 M or less (M is a volume molar concentration). If the concentration of the metal ions serving as the positive electrode and the negative electrode active material is less than 0.3 M, it is difficult to ensure sufficient energy density as a large capacity storage battery. In order to increase energy density, the higher the metal ion concentration is, the more preferably 1.0 M or more.

In the case of a redox flow battery system, it is typically connected to a renewable energy generation unit, a power system or a customer through a DC / AC generator. The above-mentioned renewable energy generation unit includes a solar generator, a wind generator, and the like, a general power plant. The renewable energy generation unit 100 performs a charging process through a solar generator, a wind generator, a general power plant.

And discharge is performed through the connection with the consumer.

In the charging and discharging, when a redox battery 10 and a circulation mechanism (an anode electrolyte reservoir, a cathode electrolyte reservoir, and a pump) for circulating an electrolyte solution are provided in the redox battery 10, a redox flow battery The system is built.

4 is a schematic diagram showing the configuration of a cell stack of a redox flow battery.

Referring to FIG. 4, the redox battery 10 separates the positive cells 13a and 13c containing the positive electrode and the negative cells 13b and 13d containing the negative electrode from the positive electrode and appropriately permeates ions. The exchange membrane 15 is provided. A positive electrode electrolyte reservoir 11a is connected to the positive cell 13a, 13c via a conduit. A cathode electrolyte reservoir 11b is connected to the cathode cells 13b and 13d through a conduit. The conduit is equipped with a pump for circulating each electrolyte.

The redox battery 10 uses the conduit and the pumps 12a and 12b in the cathode cells 13a and 13c and the anode cells 13b and 13d in the cathode electrolyte reservoir 11a and the cathode electrolyte reservoir 11b. The negative electrode electrolyte solution is circulated and supplied and charged and discharged along with the hydrolysis reaction of the metal ions serving as the active material in the electrolyte solution of each electrode.

The redox battery 10 has a form called a cell stack 22 in which a plurality of the positive electrode cells 13a and 13c and the negative electrode cells 13b and 13d are stacked. The anode cells 13a and 13c and the cathode cells 13b and 13d respectively supply a bipolar plate 17 having an anode electrode (not shown) on one side and a cathode electrode (not shown) on the other side and a liquid supply for supplying an electrolyte solution. The structure using the cell frame 16 which has a hole and a liquid discharge hole which discharges electrolyte solution, and has a frame body formed in the outer periphery of the said bipolar plate is typical. By laminating a plurality of cell frames 16, the liquid supply hole and the liquid discharge hole constitute a flow path of the electrolyte solution, and the flow path is suitably connected to the conduit. The cell stack 22 is repeatedly stacked in the order of the cell frame 16, the anode electrode 14a, the ion exchange membrane 15, the cathode electrode 14b, and the cell frame 16.

At this time, it is the bipolar plate 17 that the cathode electrode 14b and the anode electrode 14a abut together among the components constituting the cell stack 22.

The bipolar plate 17 is preferably made of a plastic carbon material.

When stacked through the bipolar plate 17, it can be said that the configuration for the operation of the redox flow battery system. However, depending on the type of electrolyte supplied between the cell frames 16, it may be a positive electrode cell or a negative electrode cell.

In addition, since the anode cell contains V ^{4 +} and V ^{5 +} ions, the cathode cell may be a cathode cell for charging or an anode cell for discharging depending on a chemical reaction induced as described above.

Similarly, since the negative electrode cell contains V ^{2 +} and V ^{3 +} ions, the negative electrode cell may be a charging negative electrode cell or a negative electrode cell for discharging depending on the induced chemical reaction.

Therefore, according to the redox flow battery system for storing renewable energy according to the present invention, since it is possible to simultaneously perform a charging function and a discharge function, power generation affected by external environmental changes such as wind power generation, solar power generation, tidal power generation and By eliminating the instability of the power transmission system, it is possible to provide a large-capacity energy system that is relatively homogeneous and provides abundant power and supply of power at all times.

In the redox battery, the ion exchange membrane 15 is a component that determines battery life and price. Examples of the ion exchange membrane 15 that can be used as the ion exchange membrane 15 include a Nafion membrane and a cellulose acetate film.

The redox battery is a secondary battery that charges and discharges by using an electromotive force difference when the ions are oxidized and reduced by circulating ions of varying valences on both half cells separated by the ion exchange membrane 15. Therefore, the intensity of the current can be controlled by adjusting the concentration of ions in the electrolyte, and the voltage can be adjusted according to the degree of stacking of the unit cells. In addition, in the case of a redox battery, compared to other batteries, it is characterized by light and low volume.

The ions used in the redox flow cell usually use elements of transition metals which may have various valences. In the case of using a different type of metal element in each half cell, mixing occurs through the ion exchange membrane 15. A decrease in capacity occurs.

However, in the vanadium redox battery as in the present invention, by using the same electrolyte as vanadium sulfate (VOSO ₄ ) for both half cells, there is no decrease in capacity of the battery due to mixing through the ion exchange membrane 15.

However, when the above-mentioned Nafion membrane is used as the ion exchange membrane 15, a significant phenomenon of efficiency decrease due to self discharge occurs due to the movement phenomenon between the positive electrode 14a and the negative electrode 14b of vanadium ions through the Nafion membrane. When the vanadium ion migration occurs, it becomes difficult to maintain the constant voltage, which is an advantage of the redox battery.

Therefore, it is important to increase the selectivity of the ion exchange membrane among the characteristics of the ion exchange membrane due to the characteristics of the redox battery as described above.

The selectivity of the ion exchange membrane refers to the property of transmitting only specific ions but not other ions.

The ion exchange membrane 15 in the redox battery should have high selectivity for ions, small electrical resistance, and small diffusion coefficient of solute and solvent. Also, it should be chemically stable, have excellent mechanical strength, and be cheap.

Among the redox batteries, vanadium-based redox batteries are excellent in acid resistance, oxidation resistance, and selective permeability because they use a material in which a transition metal element, vanadium and strong acid sulfuric acid, is used as an electrolyte. In redox batteries, ion exchange membranes are a type of consumable that must be replaced periodically. When the Nafion membrane is used as the ion exchange membrane 15 in the redox battery, energy efficiency is lowered because vanadium ions are permeated through the Nafion membrane, and in the case of the CMV membrane, the lifespan characteristics are poor.

On the other hand, in the case of a redox battery, when graphite is used as an electrode, the phenomenon occurring in the electrode is only exchange of electrons, and no change of the electrode itself occurs.

Further, since the electrodes 14a and 14b and the electrolyte material that causes the electric conduction phenomenon are separated, a complicated electrode reaction does not occur. However, only the supply of the electrolyte material stored in the positive / negative electrolyte reservoirs 11a and 11b through the pumps 12a and 12b toward the positive electrode cells 13a and 13b containing the electrodes 14a and 14b. Since the supply system of the electrolyte material is separated from the anode / cathode cells 13a and 13b serving as power supply means, it is possible to store and supply only the electrolyte separately.

It is possible to use only the electrolytes separately. In recent years, the replacement of batteries is difficult in the dissemination of electric vehicles using secondary batteries, which are lithium ion batteries. In the redox flow battery system for storing renewable energy according to the present invention, since the electrolyte is liquid, In the exchange process of the stored in the existing gas station and when the vehicle is to be refueled it can be supplied to the positive cell (13a) and the negative cell (13b). Thus, existing oiling equipment can be used.

In the case of a redox flow battery, the electrolyte of the electrode is separated and stored in the tank, and the battery output can be controlled by the inflow flow rate. Also, it is easy to manage the battery, and it is possible to estimate the amount of power storage simply by changing the tank capacity.

And the advantages as described above can be provided a stable output at the consumer, it is possible to design a large capacity battery system.

As another advantage, it is possible to cross-use the charging cells 13a and 13b and the discharge cells 13c and 13d. The cross use of the charge cells 13a and 13b and the discharge cells 13c and 13d means that the cells used as the charge cells 13a and 13b may be periodically replaced with the discharge cells 13c and 13d. . Of course, not only can be used periodically, it is also possible to exchange and use arbitrarily according to the user's operation.

That is, when the charging action is completed through the power generation device, the limit of charging is reached. Therefore, if the positive electrode cell (13a), the V ^{5 +} ions are led to the concentration limit value, in the case of the negative electrode cell (13b) is V ^{2 +} ions are led to the limit concentration values.

Therefore, it is preferable that the charge through the power generation device and the discharge through the use in the consumer cross each other. In addition, the redox flow battery system according to the present invention has a structure capable of circulating the ions, it is configured to send the ions to the positive electrolyte reservoir (11a) and the negative electrode electrolyte reservoir (11b) to be used again have.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

10: redox battery 11a: positive electrode electrolyte reservoir
11b Cathode Electrolyte Reservoir 12 Pump
13a: Rechargeable anode cell 13b: Rechargeable cathode cell
13c: Discharge positive electrode cell 13d: Discharge negative electrode cell
14a: anode 14b: cathode
15: ion exchange membrane 100: renewable energy generation unit
200: load

Claims (4)

Rechargeable anode cell and rechargeable cathode cell connected to the renewable energy generation unit,
Including a negative electrode cell and a positive electrode cell for discharge connected to the load,
A first ion exchange membrane is provided between the charging positive electrode cell and the negative electrode cell, and a second ion exchange membrane is provided between the discharge positive electrode cell and the discharge negative electrode cell.
The rechargeable positive electrode cell and the discharge positive electrode cell are connected through a positive electrode electrolyte reservoir, and the charging negative electrode cell and the discharge negative electrode cell are connected through a negative electrode electrolyte reservoir, a redox flow battery for renewable energy storage. system. The method of claim 1,
Redox flow battery system for the storage of renewable energy, characterized in that the charging anode cell and the discharge anode cell includes V ^{4 +} ions and V ^{5 +} ions. The method of claim 1,
Redox flow battery system for a renewable energy storage, characterized in that the charging negative electrode cell and the discharge negative electrode cell includes V ^{2 +} ions and V ^{3 +} ions. 4. The method according to any one of claims 1 to 3,
The charging negative electrode cell and the charging positive electrode cell may be a discharge negative electrode cell and a discharge positive electrode cell, respectively, characterized in that the redox flow battery system for the storage of renewable energy.

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