JP2002237323A - Cell frame and redox flow battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell frame which can nearly homogeneously retain the liquid amount of positive and negative electrode liquid without using a communicating tube, and provide a redox flow battery using the frame. SOLUTION: This is the cell frame possessing a manifold for the positive electrode electrolytic solution and a manifold for the negative electrode electrolytic solution, and has groove parts 70A, 70B connected with the both manifolds and a communicating hole 50 to communicate with the groove parts 70A, 70B. In cases where a solution shift happens by osmotic pressure or the like and the liquid amount of either of the positive electrode electrolytic solution or the negative electrode electrolytic solution increases, the electrolytic solution moves decreased through a slit from that in which the electrolytic solution has increased to that in which it has, and by this, non-uniform liquid amount of the positive and negative electrolytic solution can be returned to a nearly equal state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a redox flow battery cell frame and a battery using the same. In particular, the present invention relates to a cell frame structure which has high reliability with respect to leakage of electrolytes of positive and negative electrodes in a cell frame and has excellent manufacturability.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view showing the operating principle of a redox flow battery. This battery is a cell separated into a positive electrode cell 1A and a negative electrode cell 1B by a diaphragm 4 made of an ion exchange membrane.
With one. Each of the positive electrode cell 1A and the negative electrode cell 1B has a built-in positive electrode 5 and negative electrode 6. A positive electrode tank 2 for supplying and discharging a positive electrode electrolyte is connected to the positive electrode cell 1A via conduits 7 and 8. A negative electrode tank 3 for introducing and discharging a negative electrode electrolyte is also provided in the negative electrode cell 1B with the conduit 10,
Connected through 11. An aqueous solution of ions whose valence changes, such as vanadium ions, is used as each electrolytic solution. The aqueous solution is circulated by the pumps 9 and 12, and is charged and discharged in accordance with the valence change reaction of the ions at the positive and negative electrodes 5 and 6.

FIG. 6 is a schematic configuration diagram of a cell stack used for the above-mentioned battery. Usually, a configuration called a cell stack 100 in which a plurality of cells are stacked is used for the battery. Each cell includes a positive electrode 5 and a negative electrode 6 made of carbon felt on both sides of the diaphragm 4. A cell frame structure 20 is arranged outside each of the positive electrode 5 and the negative electrode 6.

The cell frame structure 20 has a bipolar plate 21 made of plastic carbon and a cell frame 22 formed on the outer periphery thereof.

[0005] In the cell frame 22, manifolds 23A, 2A
A plurality of holes called 3B are formed. One cell frame is provided with a total of eight manifolds, for example, four on the lower side and four on the upper side, two on the lower side for supplying a positive electrode electrolyte, the other two for supplying a negative electrode electrolyte, and two on the upper side for a positive electrode. An electrolyte is discharged, and the remaining two are for discharging the negative electrode electrolyte. The manifolds 23A and 23B form a flow path for the electrolyte by stacking a large number of cells. The cell frame also has slits connecting the manifolds 23A and 23B and the inner edges of the cell frame. This slit is constituted by a vertical groove portion 60A formed in the cell frame, the slit for the positive electrode electrolyte is formed on the front side of the bipolar plate 21, and the slit for the negative electrode electrolyte (not shown) is formed on the back side of the bipolar plate 21. .

By the way, in such a redox flow battery, H ⁺ ions move through the diaphragm as the battery is charged or discharged, or the pressure difference between the pump for pumping the positive electrode electrolyte and the pump for pumping the negative electrode electrolyte or the positive pressure. By the osmotic pressure between the negative electrode electrolyte,
Liquid transfer occurs in which the electrolyte moves to one electrode side through the diaphragm. Therefore, the amount of electrolyte in the positive electrode tank and the negative electrode tank is constantly fluctuating, and if the balance of this amount of electrolyte is extremely disrupted, there is a risk that the electrolyte exceeds the capacity of the tank and leaks to the outside. .

[0007] As a means for suppressing the fluctuation of the amount of the electrolyte, a technique described in Japanese Utility Model Laid-Open No. 4-124754 is known. This is achieved by connecting the tank for the positive electrode and the tank for the negative electrode with a communication pipe, and disposing one end of the communication pipe above the liquid surface of the positive electrode liquid and the other end above the liquid surface of the negative electrode liquid. When the amount of electrolyte in the tank increases, the electrolyte is moved through the communication pipe.

[0008]

However, in the above technique, the electrolyte is moved by a communication pipe connecting the positive electrode liquid storage tank and the negative electrode liquid storage tank, and the communication pipe itself must be prepared. However, there is a problem that a considerable space is required for disposing the communication pipe.

Accordingly, it is a primary object of the present invention to provide a cell frame capable of maintaining a substantially uniform amount of the positive and negative electrode solutions without using a communication tube, and a battery using the same.

[0010]

SUMMARY OF THE INVENTION The present invention achieves the above object by enabling the positive and negative electrode electrolytes to move in a cell frame.

That is, the cell frame of the present invention is a cell frame including a manifold for a positive electrode electrolyte and a manifold for a negative electrode electrolyte, and is characterized in that it has a slit communicating the two manifolds.

By connecting the cathode electrolyte manifold and the anode electrolyte manifold with slits, the cathode electrolyte and the anode electrolyte can be moved in the cell. Therefore,
When the amount of one of the liquids increases, the liquid is moved to the other through the slit, so that the liquid amount balance of the electrolytes of both electrodes can be maintained. At that time, since the electrolytic solution can be moved in the cell, the communication pipe conventionally used is unnecessary.

As a specific configuration of the slit, a groove extending from the cathode electrolyte manifold is formed on one surface of the cell frame, and a groove extending from the anode electrolyte manifold is formed on the other surface. Then, when the cell frames are stacked, the groove extending from the cathode electrolyte manifold and the groove extending from the anode electrolyte manifold partially overlap to form a communication hole connecting both grooves. Is preferred.

For example, a total of four manifolds are provided at the lower part of the cell frame, two at the lower part and two at the upper part, one of the lower part for supplying the negative electrode liquid, the other for the supply of the positive electrode liquid, one of the upper parts for the discharge of the negative electrode liquid, The case where the other is for discharging the positive electrode solution will be described as an example. A groove extending from the cathode electrolyte manifold is formed on one surface of the cell frame, and a groove extending from the anode electrolyte manifold is formed on the other surface. And
When a pair of cell frames are adjacent to each other, a communication hole is formed substantially in the middle of the positive / negative electrode liquid discharge manifold, so that both groove portions are connected.

It is preferable to reduce the size of the slit (the cross-sectional area of the communication hole and the width and depth of the groove). If the slit is large, the positive electrode electrolyte and the negative electrode electrolyte are mixed, which leads to self-discharge. If the cross-sectional area of the slit is small, when both the positive and negative electrode electrolytes are applied at substantially the same pressure, the amount of the moving electrolyte is small, and there is no problem in that the amount of the electrolyte moves is smaller than the shunt current loss in the cell.

The slits may be arranged symmetrically with respect to the communication hole, but may be arranged asymmetrically so that the electrolyte moves only from one manifold to the other. Is also good. For example, in a vanadium redox flow battery, an electrolyte moves from a positive electrode to a negative electrode through a diaphragm. Therefore, in the cell, the electrolyte may be moved only from the negative electrode to the positive electrode. In short, the slit functions as a check valve to limit the movement of the electrolyte in the cell to one direction. More specifically, the groove connected to the manifold for discharging the negative electrode solution may be higher than the groove connected to the manifold for discharging the positive electrode solution.

Further, the slit is constituted by a groove connecting the manifolds and a communication hole connecting the grooves, and a step is provided at a position higher than the communication hole between the communication hole and each manifold. Is preferred. With this configuration, when the liquid increased in the cell of one electrode passes through the slit and enters the cell of the other electrode, it moves to the other electrode side through the slit without flowing out of the manifold to the outside of the cell (positive / negative tank). Can be done.

The battery of the present invention is characterized by using the above-mentioned cell frame. Except for the point that the configuration of the cell frame is different from the conventional one, the other configuration may be basically the same as the conventional redox flow battery. The cell frame of the present invention can be applied to any of an electrolyte circulation battery, an intermittent electrolyte circulation battery, and an electrolyte stationary battery.

[0019]

Embodiments of the present invention will be described below. (Embodiment 1) FIG. 1 is a plan view of a cell frame 22 of the present invention. The cell frame 22 is a plastic plate formed in a frame shape, and a bipolar plate 21 made of plastic carbon is fitted in a hollow portion in the center. A lower portion of the frame portion has a positive electrode electrolyte supply manifold 23A and a negative electrode electrolyte supply manifold 23B, and an upper side has a positive electrode electrolyte discharge manifold 24A and a negative electrode electrolyte discharge manifold 24B. Each of the manifolds 23A, 23B, 24A, and 24B is a hole that penetrates the cell frame, and forms a flow path for the electrolyte in the stacking direction when a plurality of cells are stacked. The positive (negative) electrode electrolyte supply manifolds 23A and 23B and the positive (negative) electrode electrolyte discharge manifolds 24A and 24B are formed substantially diagonally.

Each of these manifolds has a vertical groove 60A, 60B and a concave groove 6 communicating with the positive electrode or the negative electrode.
1A and 61B are formed. In this example, the supply manifolds 23A and 23B are connected to the linear vertical grooves 60A and 60B, and the discharge manifolds 24A and 24B are connected to the concave grooves 61A and 61B.
That is, the electrolyte is supplied from the positive (negative) electrode electrolyte supply manifold to the positive (negative) electrode through the vertical grooves 60A and 60B,
The electrolyte is discharged to the positive and negative electrode electrolyte discharge manifolds 24A and 24B through the concave grooves 61A and 61B. A vertical groove 60A connected to the cathode electrolyte supply manifold and a concave groove 61A connected to the cathode electrolyte discharge manifold are formed on the surface side of the cell frame (indicated by a solid line), and a vertical groove 60B connected to the anode electrolyte supply manifold. And the concave groove 61B connected to the negative electrode electrolyte discharge manifold are formed on the back side of the cell frame (indicated by broken lines).

The concave grooves 61A and 61B function as a part of a slit communicating with the manifolds 24A and 24B for discharging the positive and negative electrode electrolytes. The slit has linear horizontal grooves 70A, 70B connected to the concave grooves 61A, 61B. II-I in Fig. 1
FIG. 2 shows an I section. FIG. 2 shows a state in which two cell frames of FIG. 1 are stacked. When the two cell frames are adjacent to each other, the ends of the horizontal groove 70A in one cell frame and the horizontal groove 70B in the other cell frame overlap, and the communication hole 50 is formed at the overlapping portion. With this configuration, the manifolds 24A and 24B for discharging the positive and negative electrode electrolytes are communicated. It is preferable that the width of the horizontal grooves 70A and 70B is narrower than the width of the concave grooves 61A and 61B (FIG. 1), and the length is long to suppress mixing of the positive and negative electrode electrolytes during circulation of the electrolyte. Further, it is preferable that the depth of the horizontal grooves 70A and 70B is formed to be shallow so that excessive movement of the electrolyte does not occur. Furthermore, in this example, the communication hole 50, the horizontal grooves 70A and 70B, and the horizontal portions of the concave grooves 61A and 61B are connected to the manifolds 24A and 24B, respectively.
Formed at a higher position.

Normally, the amounts of the positive electrode electrolyte and the negative electrode electrolyte are almost evenly balanced. When both electrolytes are supplied at substantially equal pressures, there is almost no movement of the electrolyte through the communication slit. There is no problem with battery performance. On the other hand, when liquid transfer occurs and the amount of either the positive electrode electrolyte or the negative electrode electrolyte increases, the amount of the electrolyte moves from the increased side to the smaller side through the communication slit, thereby causing uneven positive and negative electrolysis. The liquid volume can be returned to a substantially uniform state.

In a redox flow battery using such a cell frame, a positive electrode and a negative electrode made of carbon felt are arranged on both sides of a diaphragm as in the prior art. Then, a cell frame is arranged outside each of the positive electrode and the negative electrode, and the same lamination is sequentially repeated to form a cell stack. A tank for supplying and discharging the positive electrode electrolyte and a manifold for supplying (discharging) the positive electrode electrolyte are connected by a conduit, and a tank for the negative electrode and a supplying (discharging) the negative electrode electrolyte for introducing and discharging the negative electrode electrolyte The connection to the manifold and the conduit is the same as in the conventional battery. However, since the battery of the present invention enables the movement of the electrolyte in the cell, it is not necessary to use a communication pipe for correcting unevenness in the amount of the electrolyte.

(Embodiment 2) Next, a cell frame having a left-right asymmetric communication slit will be described with reference to FIG. This cell frame is on the side where the amount of electrolyte increases due to the transfer of electrolyte (negative electrode side in vanadium redox flow batteries)
By increasing the height of the slit, the electrolyte on one electrode can be returned to the other electrode without flowing through the manifold.

That is, the negative electrode solution discharge manifold 24B
The horizontal portion of the concave groove portion 61B connected to the groove portion 61B is the highest, and sequentially decreases in the order of the horizontal groove portion 72B from the concave groove portion 61B to the communication hole 50 and the L-shaped groove portion 72A from the communication hole 50 to the concave groove portion 61A. The height of the horizontal portion of the concave groove portion 61A connected to the positive electrode solution discharge manifold 24A was substantially equal to that of the L-shaped groove portion 72A. Also in this embodiment, when a pair of cell frames are joined,
The communication hole 50 is formed at an overlapping portion between the tip of the horizontal groove 72B in one cell frame and the tip of the L-shaped groove 72A in the other cell frame to form a slit.

When the cell frame having this structure is used in a vanadium redox flow battery, the amount of electrolyte on the negative electrode side increases, but the electrolyte flows into the horizontal groove 72B and the communication hole before flowing through the negative electrode discharge manifold 24B. 50 and L-shaped groove 72
Since it is returned to the positive electrode side via A, the amount of the electrolyte in the negative electrode tank can be suppressed from exceeding the allowable amount.

The structure of the redox flow battery using the cell frame is the same as that of the first embodiment, and the description is omitted.

(Embodiment 3) Next, FIG. 4 shows a cell frame in which a step portion 80, which is a symmetrical slit but is located higher than the communication hole between the communication hole and each manifold, is formed.
It will be described based on. In this cell frame, a step portion 80 having a reduced groove width is formed in a horizontal portion of the concave groove portions 61A and 61B connected to each manifold, and the height of the step portion is configured to be higher than the communication hole 50. Also in this embodiment, when two cell frames are adjacent to each other, the ends of the horizontal groove 73A in one cell frame and the horizontal groove 73B in the other cell frame overlap, and the communication hole 50 is formed at the overlap. Thus, a slit is formed.

When the cell frame having this structure is used in a redox flow battery, the amount of electrolyte on one electrode side increases, but the step portion 80 causes the electrolyte to flow into the horizontal groove 73A before flowing into the one-electrode solution discharge manifold. , 73B and the communication hole 50 to return to the other electrode side, so that the amount of electrolyte in the unipolar tank can be suppressed from exceeding the allowable amount.

The structure of the redox flow battery using the cell frame is the same as that of the first embodiment.

When the cell frame of this embodiment is operated as an electrolyte stationary battery and the electrolyte is replaced from the lower manifold for maintenance or the like, there is a step in the concave groove, so that the inside of the slit (horizontal groove 73A, The electrolyte collects in 73B). As a result, self-discharge, shunt current, or the like flows through the remaining electrolytic solution, which may lead to a reduction in efficiency. To remove the residual electrolyte in this slit, tilt the cell,
It may be performed by blowing off with a nitrogen gun.

[0032]

As described above, according to the present invention, the following effects can be obtained.

By providing the cell frame with a slit for communicating the positive and negative electrode electrolytes, the electrolyte can be moved in the cell, and the amounts of the positive electrode electrolyte and the negative electrode electrolyte can be kept substantially uniform. .

Since the movement of the electrolytic solution is performed in the cell, there is no need to arrange a communication pipe as in the prior art, and it is not necessary to consider a piping space for the communication pipe. It is sufficient to simply form the groove and the communication hole in the cell frame, and the cost can be reduced as compared with the case where the communication pipe is used.

By arranging the slits asymmetrically in the left and right directions, the electrolyte is moved from one manifold to the other manifold only, so that unnecessary communication of the electrolyte in the cell can be prevented.

By forming a step portion at a position higher than the communication hole between the communication hole and each manifold, the step portion allows the electrolytic solution to flow to the horizontal groove portion and the communication hole before flowing into the unipolar solution discharge manifold. And since it is returned to the other electrode side through the horizontal groove, it is possible to suppress the amount of the electrolyte in the unipolar tank from exceeding the allowable amount.

[Brief description of the drawings]

FIG. 1 is a plan view of a cell frame of the present invention in which slits are symmetrical.

FIG. 2 shows a state in which two slits are adjacent to each other in FIG.
It is II-II sectional drawing.

FIG. 3 is a plan view of a cell frame of the present invention in which slits are left-right asymmetric.

FIG. 4 is a plan view of the cell frame of the present invention in which a step portion is formed.

FIG. 5 is an explanatory diagram of the operation principle of a redox flow battery.

FIG. 6 is a schematic configuration diagram of a cell stack used for a redox flow battery.

[Explanation of symbols]

 1 cell 1A Positive cell 1B Negative cell 2 Positive electrode tank 3 Negative electrode tank 4 Diaphragm 5 Positive electrode 6 Negative electrode 7, 8, 10, 11 Conduit 9, 12 Pump 100 Cell stack 20 Cell frame structure 21 Bipolar plate 22 Cell frame 23A , 23B, 24A, 24B Manifold 50 Communication hole 60A, 60B Vertical groove 61A, 61B, 71B Recessed groove 70A, 70B, 72B, 73A, 73B Horizontal groove 71A, 72A L-shaped groove 80 Stepped section 100 Cell stack

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyuki Tokuda 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Osaka Kansai Electric Power Company F-term (reference) 5H026 AA10 CC08 CV06 HH03 5H027 AA10 MM01

Claims (4)

[Claims] 1. A cell frame comprising a cathode electrolyte manifold and a negative electrode electrolyte manifold, wherein the cell frame has a slit communicating the two manifolds. 2. The cell frame according to claim 1, wherein the arrangement of the slits is asymmetrical so that the electrolyte moves from one manifold to only the other manifold. 3. The slit has a groove portion connected to each manifold and a communication hole communicating with both groove portions, and has a step portion at a position higher than the communication hole between the communication hole and each manifold. The cell frame according to claim 1, wherein: 4. A redox flow battery using the cell frame according to claim 1.