KR20150056953A - A redox flow battery with bipolar plates which can be aligned easily - Google Patents

Abstract

The present invention relates to a redox flow battery and, more specifically, to a redox flow battery having a separation plate of a structure to be self-aligned and easily sealed without an additional alignment tool or device. According to the present invention, the redox flow battery comprises a plurality of unit cells including a pair of separation plates, a pair of electrodes which are placed between the separation plates, and membranes which are arranged between the electrodes. The separation plates includes uneven portions formed in the edge of the separation plate in order to align the separation plates fitting one another. The redox flow battery according to the present invention can be easily aligned using the uneven portions formed in the edge of the separation plate without an additional means for alignment. Moreover, the present invention is capable of sealing the unit cells using the uneven portions without using an additional gasket.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a redox flow battery having bipolar plates,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a redox flow cell, and more particularly, to a redox flow battery having a separation plate that is self-aligning and can be easily sealed without a separate alignment tool or apparatus .

Recently, renewable energy such as solar energy or wind energy is attracting attention as a method for suppressing greenhouse gas emission, which is a major cause of global warming. However, renewable energy is heavily influenced by location conditions and natural conditions. Moreover, since the output fluctuation is significant, the energy can not be continuously supplied uniformly. Therefore, in order to use renewable energy for home or commercial use, a system is used in which energy is stored when the output is high and energy stored when the output is low.

As such an energy storage system, a large-capacity secondary battery is used. For example, a large-capacity secondary battery storage system is introduced into a large-scale solar power generation and wind power generation complex. The secondary battery for storing a large amount of electric power includes a lead storage battery, a NaS battery, and a redox flow battery (RFB). Although the lead-acid battery is widely used in comparison with other batteries, it has disadvantages such as low efficiency and maintenance cost due to periodical replacement and disposal of industrial waste generated when the battery is replaced. The NaS battery has a disadvantage in that it operates at a high temperature of 300 ° C or higher, although it has an advantage of high energy efficiency. Redox flow cells have a low maintenance cost and can be operated at room temperature. Since the capacity and output can be designed independently of each other, a lot of research has been conducted with a large capacity secondary battery.

 In the redox flow cell, a positive electrode electrolyte and a negative electrode electrolyte are circulated on both sides of the membrane, and ion exchange is performed. In this process, electrons move and charge and discharge are performed. Such a redox flow battery is known to be most suitable for an energy storage system (ESS) because it can be manufactured as a medium to large-sized system of a kW to MW class as compared with a conventional secondary battery.

Therefore, recent studies on redox flow cell have been made. For example, Korean Patent Laid-Open Publication No. 10-2011-0119775 discloses a lithium secondary battery in which a positive electrode electrolyte, a negative electrode, and a diaphragm interposed between the positive and negative electrodes are supplied to a battery cell, Wherein the anode electrolyte contains manganese ions and the cathode electrolyte contains at least one metal ion selected from titanium ion, vanadium ion, chromium ion, zinc ion and tin ion, and precipitation of MnO ₂ And a precipitation inhibiting means for suppressing precipitation of the redox flow cell. In Korean Patent No. 1176126, a plurality of bipolar plates, an electrode divided into positive and negative electrodes, and a membrane are stacked in series, and a plurality of stacked bipolar plates are provided with redox The flow cell structure is characterized in that the bipolar plate has an electrolyte inlet and an electrolyte outlet formed at a lower portion and an upper portion of the bipolar plate, and a flow path is formed between the electrolyte inlet and the electrolyte outlet so as to move the electrolyte, and the electrolyte inlet and the electrolyte outlet A short-circuiting pipe made of an insulating material is inserted in the flow-through hole to prevent contact between the electrolytic solution passing through the through-hole and the bipolar plate, and the short- Outside the bipolar plate When the laminate to ensure that the projecting part is compacted electrodes that are provided on both sides of the flow plate by redox flow cell structure, characterized in that to prevent electrolyte leakage between the bipolar plate and the electrode is disclosed.

FIG. 1 is a schematic structural view for explaining the structure of a conventional redox flow cell, and FIG. 2 is a cross-sectional view schematically showing the structure of a unit cell of a conventional redox flow cell. As shown in FIGS. 1 and 2, a redox flow cell has a structure in which a membrane 10, electrodes 11 and 12, and a bipolar plate 20 are arranged in series, (Secondary battery) capable of charging and discharging electric energy.

Korean Patent Publication No. 10-2011-0119775 Korean Patent No. 1176126 Korean Patent No. 1149351

Conventional redox flow cells are assembled by applying compressive force to a separator and a rigid carbon fiber felt, fabric or mat.

In this case, a method of arranging a gasket between the frame and the separating plate and applying pressure, and a method of securing the hermeticity by constructing a bonding structure between the frame and the separating plate have been devised. The frame serves as a flow path for supplying and discharging the electrolyte in the redox flow cell, and is produced through machining. The design of the flow path using the frame has the advantage that the shape of the flow path can be designed relatively freely. However, since the thickness of the frame is thin and the area is wide, there is a problem that the processing cost is considerably high. Although it is possible to manufacture by using the plastic injection molding method in mass production, in the case of a large capacity ESS, an expensive mold and an injection molding machine of a large capacity are required because of a large frame structure.

In the conventional structure, when the gasket is used between the frame and the separator to secure airtightness, the assembling time is considerably long, the alignment of the components is difficult, and it is difficult to reassemble and repair or supplement it later.

Also, when a plastic material such as acrylic, polypropylene, PP, polycarbonate (PC), or polyvinyl chloride (PVC) is used as a frame, There is a possibility that the electrolytic solution is leaked to the electrode.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a redox flow cell having a cell structure in which no frame or frame can be minimized. It is another object of the present invention to provide a redox flow cell capable of aligning a separation plate without a separate alignment guide at the time of assembly.

According to an aspect of the present invention, there is provided a redox flow cell comprising a pair of separation plates, a pair of electrodes disposed between the pair of separation plates, and a plurality of membranes disposed between the pair of electrodes Wherein the separator plates are provided with recesses and protrusions formed at edges of the separator plate so that the separator plates can be aligned with each other.

The redox flow battery may further include a frame disposed between the concavo-convex portions.

Preferably, the concave-convex part has a pair of inclined surfaces which are projected in one direction and are inclined so as to approach each other in a protruding direction, and neighboring concave-convex parts are overlapped such that the inclined surfaces are in contact with each other.

In the redox flow cell described above, a flow path for supplying the electrolyte and a flow path for collecting the electrolyte may be provided in the uneven portion.

The redox flow cell may further include an inner convex / concave portion formed on the inner side of the concave / convex portion, and a flow path for supplying the electrolyte and a flow path for collecting the electrolyte may be provided on the inner convex / concave portion.

In addition, the membrane may include a membrane concavo-convex portion corresponding to the concavo-convex portion of the separation plate so that the membrane can be aligned with the adjacent separation plates.

The redox flow cell according to the present invention can be easily aligned by using the uneven portion formed on the edge of the separator plate without any means for alignment. Further, the unit cell can be sealed by using the concave-convex portion without using a separate gasket.

1 is a schematic structural view illustrating a structure of a conventional redox flow cell.
2 is a cross-sectional view schematically showing the structure of a unit cell of a conventional redox flow cell.
3 is a schematic view of unit cells of an embodiment of a redox flow cell according to the present invention.
4 is a schematic view showing a state in which the respective components of the unit cells shown in FIG. 3 are separated.
Figures 5 and 6 are schematic diagrams showing other embodiments of unit cells.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

3 is a schematic view of unit cells of an embodiment of a redox flow cell according to the present invention. 4 is a schematic view showing a state in which the respective components of the unit cells shown in FIG. 3 are separated. Referring to FIGS. 3 and 4, the unit cell of the redox flow cell according to the present invention includes a membrane 10, a pair of electrodes 11 and 12, and a pair of separation plates 30. The redox flow cell includes a plurality of unit cells and a pair of end plates disposed at both ends of the unit cell stack (see FIG. 1).

The pair of electrodes 11 and 12 may be composed mainly of a carbon material such as carbon fiber, carbon felt, graphite fiber, and graphite felt. In order to improve the electrochemical activity of these electrodes and increase energy efficiency and durability, the surface of the electrode can be subjected to thermal treatment, flame treatment, plasma treatment, gamma ray treatment, or acidic treatment.

The separator 30 separates the unit cells and becomes a passage through which current generated in the battery flows. The separator plate 30 may be made of a metal or a conductive polymer material.

At the edges of the separating plates 30, there are formed concave and convex portions 35 serving as a reference for easily aligning the adjacent separating plates 30. As shown in FIGS. 3 and 4, it is preferable that the concave-convex portion 35 has a trapezoidal shape in which one end face thereof is opened, as shown in FIGS.

The protrusions and depressions 35 may be provided with a flow path for supplying and discharging the electrolyte. The electrolyte stored in the electrolyte storage portions 50 and 60 (see FIG. 1) is supplied to the cell stack through a flow path, and a plurality of And an electrolyte solution is supplied to the unit cells.

The hydrogen cations generated by the oxidation reaction of hydrogen in the anode 11 of the redox flow cell migrate to the cathode 12 through the membrane 10. The membrane irregularities 15 corresponding to the irregularities 35 of the separation plate 30 are formed at the edges of the membrane 10 so as to be aligned with the adjacent separation plates 30 .

The uneven portions 35 and the membrane irregularities 15 of the adjacent separating plates 30 are overlapped with the inclined surfaces so that when the pressure is applied to the cell stack by the end plates, The concave and convex portions 15 are brought into close contact with each other, and the space between the separating plates 30 and the membrane 10 is sealed. Therefore, the concave-convex portions 35 and the membrane concave-convex portions 15 serve not only to align the separation plates 30 and the membrane 10, but also to serve as a gasket for sealing the unit cells.

Figures 5 and 6 are schematic diagrams showing other embodiments of unit cells.

As shown in FIG. 5, if necessary, the frame 40 may be disposed in a space between the concave-convex portions 35. In this case, the frame 40 can be minimized only for flow passage formation.

As shown in FIG. 6, a plurality of concavities and convexities may be formed on one separator plate 30. At this time, the outer concave / convex portion 35 provides a sealing force and a self-aligning function, and the inner convex / concave portion 38 can be used for installing a flow path for supplying and discharging the electrolyte. In this embodiment, the concave and convex portions are not formed on the membrane 10, and the unit cells are sealed while the concave and convex portions 35 of the adjacent separating plate 30 are in close contact with each other.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

For example, the cross-section of the concavo-convex portion may be a quadrilateral or semicircular opening with one side open.

10: membrane 11, 12: electrode
30: separation plate 35: concave /
40: frame

Claims (7)

A redox flow cell comprising a plurality of unit cells including a pair of separators, a pair of electrodes disposed between the pair of separators, and a membrane disposed between the pair of electrodes,
Wherein the separating plates are provided with recesses and protrusions formed on edges of the separating plates so that the separating plates can be aligned with each other. The method according to claim 1,
And a frame disposed between the concave and convex portions. The method according to claim 1,
Wherein the separation plate further comprises an inner convex / concave portion formed inside the convexo-concave portion. The method according to claim 1,
Wherein the convexo-concave portion is protruded in one direction and has a pair of inclined surfaces that are inclined so as to approach each other in a protruding direction, and adjacent convexo-concave portions are overlapped such that the inclined surfaces are in contact with each other. The method according to claim 1,
Wherein the flow path for supplying the electrolyte and the flow path for collecting are provided in the uneven portion. The method of claim 3,
Wherein a flow path for supplying the electrolyte and a flow path for collecting the electrolyte are provided in the inner convexo-concave portion. The method according to claim 1,
Wherein the membrane has a membrane irregular portion corresponding to the concavo-convex portion of the separation plate so that the membrane can be fitted and aligned with the adjacent separation plates.

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