WO2020136721A1 - Battery cell, cell stack, and redox flow battery - Google Patents

Abstract

This battery cell, which is provided with an electrode and a dipolar plate facing one surface of the electrode, is provided with one or more flow passages that are continuously disposed at one or both of the electrode and the dipolar plate from the supply edge side to the discharge edge side of an electrolyte, wherein one end of at least one flow passage among two flow passages adjacent to each other when viewed in a plan view from the stacking direction of the electrode and the dipolar plate is open to the supply edge or the discharge edge, and the volumes of the adjacent flow passages are different.

Description

Battery cells, cell stacks, and redox flow batteries

The present disclosure relates to a battery cell, a cell stack, and a redox flow battery.

　One of the storage batteries is the redox flow battery. The redox flow battery supplies an electrolytic solution to the electrodes to carry out a battery reaction. Specifically, as described in FIG. 19 of Patent Document 1, a redox flow battery has a positive electrode, a negative electrode, a diaphragm interposed between both electrodes, and a bipolar plate on which the electrodes are arranged. And a cell frame. Typically, a redox flow battery is used in a state called a cell stack in which a cell frame (bipolar plate), a positive electrode, a diaphragm, a negative electrode, and the next cell frame (bipolar plate) are repeatedly stacked in this order (Patent (Reference 19 FIG. 19).

JP, 2005-122230, A

The battery cell of the present disclosure is
A battery cell comprising an electrode and a bipolar plate facing one surface of the electrode,
One or both of the electrode and the bipolar plate are provided with one or more flow passages continuously provided from the supply edge side of the electrolytic solution toward the discharge edge side,
Of the two flow channels adjacent to each other in a plan view from the stacking direction of the electrode and the bipolar plate, at least one end of the flow channel has an opening at the supply edge or the discharge edge, and the adjacent flow channels. Have different volumes.

The cell stack of the present disclosure is
A battery cell according to the present disclosure is provided.

The redox flow battery of the present disclosure is
The battery cell of this indication or the cell stack of this indication is provided.

FIG. 1 is an explanatory diagram schematically showing the basic structure of the redox flow battery of the embodiment. FIG. 2 is a schematic configuration diagram of the battery cell and the cell stack of the embodiment. FIG. 3A is a partial plan view showing an example of a bipolar plate provided in the battery cell of the embodiment and having a linear groove. FIG. 3B is a partial cross-sectional view showing an example of a cross section of the bipolar plate shown in FIG. 3A taken along the line (B)-(B). FIG. 3C is a partial cross-sectional view showing another example of a cross section obtained by cutting the bipolar plate provided in the battery cell of the embodiment along a plane orthogonal to the flow direction of the electrolytic solution along the shape of the flow path. FIG. 3D is a partial plan view showing another example of the bipolar plate provided in the battery cell of the embodiment and having a linear groove. FIG. 3E is a partial plan view showing still another example of a bipolar plate provided in the battery cell of the embodiment and having a linear groove. FIG. 4A is a partial plan view showing an example of a bipolar plate provided in the battery cell of the embodiment and having a meandering groove. FIG. 4B is a partial plan view showing another example of the bipolar plate provided in the battery cell of the embodiment and having the meandering groove. FIG. 5A is a partial plan view showing an example of a bipolar plate provided in the battery cell of the embodiment and having a saw blade groove. FIG. 5B is a partial plan view showing another example of the bipolar plate provided in the battery cell of the embodiment and having a saw blade groove. FIG. 5C is a partial plan view showing another example of a bipolar plate provided in the battery cell of the embodiment and having a saw blade groove. FIG. 6 is an exploded perspective view showing another example of the battery cell of the embodiment.

[Problems to be solved by the present disclosure]
A redox flow battery capable of more efficient battery reaction is desired.

Patent Document 1 discloses a bipolar plate provided with a groove serving as a flow path of an electrolytic solution. In this bipolar plate, a plurality of vertical grooves extending in the electrolyte flow direction (the vertical direction in FIG. 1 of Patent Document 1) are spaced apart in the direction orthogonal to the electrolyte flow direction (the horizontal direction in the above figures). It is provided. In such a vertical groove, it is considered that the electrolytic solution flows too much and the unreacted electrolytic solution is discharged. If the unreacted electrolytic solution is discharged, the electrolytic solution cannot sufficiently diffuse into the electrode, and the electrode cannot sufficiently perform the battery reaction.

Therefore, an object of the present disclosure is to provide a battery cell capable of constructing a redox flow battery that can efficiently perform a battery reaction. Another object of the present disclosure is to provide a cell stack capable of constructing a redox flow battery capable of efficiently performing a battery reaction. Further, another object of the present disclosure is to provide a redox flow battery capable of efficiently performing a battery reaction.

[Effect of the present disclosure]
The battery cell of the present disclosure and the cell stack of the present disclosure can construct a redox flow battery capable of efficiently performing a battery reaction. The redox flow battery of the present disclosure can efficiently perform a battery reaction.

[Description of Embodiments of the Present Disclosure]
First, the embodiments of the present disclosure will be listed and described.
(1) A battery cell according to one aspect of the present disclosure is
A battery cell comprising an electrode and a bipolar plate facing one surface of the electrode,
One or both of the electrode and the bipolar plate are provided with one or more flow passages continuously provided from the supply edge side of the electrolytic solution toward the discharge edge side,
Of the two flow channels adjacent to each other in a plan view from the stacking direction of the electrode and the bipolar plate, at least one end of the flow channel has an opening at the supply edge or the discharge edge, and the adjacent flow channels. Have different volumes.

The battery cell of the present disclosure includes, as two adjacent flow paths, a specific set in which one flow path has a relatively large volume and the other flow path has a relatively small volume. Such a battery cell of the present disclosure can construct a redox flow battery (hereinafter sometimes referred to as an RF battery) that can perform a battery reaction more efficiently. The reason for this is considered as follows.

The flow channels A and B have a relatively large volume (hereinafter, may be referred to as channel A) and a relatively small volume channel (hereinafter, may be referred to as channel B). When the electrolytic solution flows through the inside, the state in which the pressure drops, that is, the distribution of the pressure drop easily becomes different. As a result, a pressure difference occurs between the adjacent flow paths A and B, and the flow of the electrolytic solution across the flow paths A and B is likely to occur. That is, the electrolytic solution is easily diffused so as to spread around the both flow paths A and B. In such a battery cell of the present disclosure, a battery reaction easily occurs in a wider range, and the battery reaction can be promoted. Therefore, the battery cell of the present disclosure contributes to improvement in efficiency of battery reaction.

(2) As an example of the battery cell of the present disclosure,
The adjacent channels may have the same planar shape but different groove widths.

In addition to contributing to the improvement of the efficiency of the battery reaction as described above, the above-described form has a simple shape of the adjacent flow passages and is excellent in the productivity of the bipolar plate and the electrode. In addition, the planar shape of the flow path here is a shape viewed from the stacking direction of the electrode and the bipolar plate, a shape viewed from the thickness direction of the electrode, or a shape viewed from the thickness direction of the bipolar plate. Is.

(3) As an example of the battery cell of (2) above,
The planar shape of the flow path may be rectangular or meandering.

　The shape of the flow channel in a rectangular shape has excellent electrolyte flowability. Further, in this form, the shape of the flow path is simpler, and the formability of the bipolar plate and the electrode is superior.

The shape of the flow channel in a meandering shape can promote diffusion of the electrolyte solution around the flow channel as compared with the case of the rectangular flow channel described above. The friction between the electrolytic solution flowing in the serpentine flow path and the inner wall forming the flow path changes according to the flow direction of the electrolytic solution in the flow path. As a result, the difference in distribution of pressure drop during the passage of the above-described electrolytic solution between the adjacent flow channels A and B, and thus the pressure difference between the flow channels A and B is more likely to occur. .. In the above-mentioned form, the electrode can favorably perform the battery reaction by the diffusion of the above-mentioned electrolytic solution. Therefore, the said form contributes to the further improvement of the efficiency of a battery reaction.

(4) As an example of the battery cell of (2) above,
The planar shape of the flow path may be a shape in which the groove width changes periodically in the longitudinal direction of the flow path.

The flow channel having a shape in which the groove width changes periodically in the longitudinal direction (hereinafter, may be referred to as a repetitive flow channel having a predetermined shape) is formed in the periphery of the flow channel as compared with the rectangular flow channel described above. The diffusion of the electrolytic solution can be promoted. The friction between the electrolytic solution flowing through the flow channel having a predetermined shape and the inner wall forming the flow channel changes according to the flow direction of the electrolytic solution in the flow channel. As a result, a difference is more likely to occur in the pressure drop distribution when the above-described electrolytic solution flows between the adjacent channel A and channel B. Further, in the repetitive flow path having a predetermined shape, the state of pressure decrease in the flow direction of the electrolytic solution in the flow path changes periodically. Therefore, if the adjacent channels A and B are repetitive channels having a predetermined shape, the volumes of the channels A and B are different, and thus the phase of the cycle relating to the distribution of the pressure drop is shifted. Due to the phase shift of the cycle, the pressure difference between the flow paths A and B tends to increase, and the electrolytic solution flowing between the flow paths A and B tends to increase. That is, the electrolytic solution is easily diffused so as to spread around the both flow paths A and B. In the above-mentioned form, the electrode can favorably perform the battery reaction by the diffusion of the above-mentioned electrolytic solution. Therefore, the said form contributes to the further improvement of the efficiency of a battery reaction.

(5) As an example of the battery cell of (4) above,
An example is a form in which the plane shape is a double-edged saw shape.

In the double-edged serrated flow path in the above embodiment, the friction between the electrolytic solution flowing through this flow path and the inner wall forming this flow path changes according to the flow direction of the electrolytic solution within this flow path. As a result, the difference in the distribution of the decrease in pressure when the above-described electrolytic solution flows is more likely to occur between the adjacent channel A and channel B. As a result, the above-mentioned pressure difference between the flow paths A and B is likely to be larger, and the electrolytic solution flowing between the flow paths A and B is more likely to be increased. Therefore, the diffusion of the electrolytic solution around the both flow paths A and B is easily promoted. Further, the double-edged saw-like flow path has a relatively wide groove width and thus an angular shape where the flow velocity of the electrolytic solution is relatively low. The electrolytic solution is likely to temporarily stay in this angular area and easily diffuse around the area. In the above-described embodiment, the diffusion of such an electrolytic solution allows the electrode to better perform the battery reaction. Therefore, the said form contributes to the further improvement of the efficiency of a battery reaction.

(6) As an example of the battery cell of (5) above,
An example is a mode in which the saw blades in the adjacent flow paths have opposite directions.

In the above-described embodiment, as described above, the difference in the distribution of the pressure drop in the double-edged saw-shaped channel (the change in the pressure drop state) is large, and the saw blade is in the opposite direction, so The pressure difference between A and B tends to increase further. As a result, the diffusion of the electrolyte solution around the both flow paths A and B is more likely to be promoted. Therefore, in the above-mentioned form, the electrode can perform the battery reaction better. Therefore, the said form contributes to the further improvement of the efficiency of a battery reaction.

(7) As an example of the battery cell of the present disclosure,
Of the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is One example is a configuration in which one end of the flow path is open to the supply edge or the discharge edge, and the other end is a one-end closed groove that does not open to both the supply edge and the discharge edge.

In the above embodiment, the pressure difference between the adjacent communication groove and the one-end closed groove is likely to be larger than when the communication grooves are adjacent to each other. As a result, the electrolytic solution flowing between the communication groove and the one-end closed groove tends to increase. Therefore, the diffusion of the electrolytic solution around the communication groove and the one-end closed groove is easily promoted. Further, since the above-described embodiment includes the one-end closed groove, a portion of the electrode near the closed end of the one-end closed groove can be used as a region (hereinafter, may be referred to as a utilization region) in which the battery reaction occurs. In such a form, the electrode can perform the battery reaction more favorably and contributes to the further improvement of the efficiency of the battery reaction.

(8) As an example of the battery cell of the present disclosure,
The adjacent channels have the same planar shape but different groove widths,
The planar shape of the flow path is a meandering shape,
Further, among the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is One example is a configuration in which one end of the flow path is open to the supply edge or the discharge edge, and the other end is a closed end groove that is not open to both the supply edge and the discharge edge.

The above-mentioned form can promote the diffusion of the electrolyte solution around the flow path, as described in (2), (3), and (7) above. Therefore, the above-described embodiment contributes to further improvement of the efficiency of the battery reaction because the electrode can favorably perform the battery reaction due to the diffusion of the electrolytic solution.

(9) As an example of the battery cell of the present disclosure,
The adjacent channels have the same planar shape but different groove widths,
The planar shape is a double-edged saw shape,
Further, among the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is One example is a configuration in which one end of the flow path is open to the supply edge or the discharge edge, and the other end is a closed end groove that is not open to both the supply edge and the discharge edge.

As described above in (2), (4), (5), and (7), the above-described embodiment can promote the diffusion of the electrolyte solution around the flow passages, and at the same time, across the adjacent flow passages. The flowing electrolytic solution tends to increase. Therefore, the above-described embodiment contributes to further improvement of the efficiency of the battery reaction because the electrode can favorably perform the battery reaction due to the diffusion of the electrolytic solution.

(10) As an example of the battery cell according to any one of (7) to (9) above,
The volume of the one-end closed groove may be larger than the volume of the communication groove.

The above-mentioned form makes it easy to secure a large electrode utilization area. Therefore, in the above-described embodiment, the electrode can favorably perform the battery reaction, and contributes to further improvement in the efficiency of the battery reaction.

(11) A cell stack according to an aspect of the present disclosure is
The battery cell according to any one of (1) to (10) above is provided.

Since the cell stack according to the present disclosure includes the above-described battery cell according to the present disclosure, it is possible to construct an RF battery capable of more efficient battery reaction.

(12) A redox flow battery (RF battery) according to an aspect of the present disclosure,
The battery cell according to any one of (1) to (10) above or the cell stack of (11) above is provided.

Since the RF battery of the present disclosure includes the battery cell of the present disclosure described above or the cell stack of the present disclosure described above, the battery reaction can be performed more efficiently.

[Details of the embodiment of the present disclosure]
Hereinafter, a battery cell, a cell stack, and a redox flow battery (RF battery) according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same reference numerals mean the same names.

[Embodiment]
First, an outline of the battery cell 1, cell stack 5, and RF battery 10 of the embodiment will be described with reference to FIGS. 1 and 2. Then, the flow path 3 provided in the battery cell 1 of the embodiment will be described in detail. As will be described later, one battery cell 1 includes a positive electrode 13 and a negative electrode 14 as electrodes 12 and two bipolar plates 2. In the following description, at least one of the positive electrode 13 and the negative electrode 14 will be mainly described as the electrode 12. Regarding the bipolar plate 2, one bipolar plate 2 will be described as a representative.

(Overview)
The battery cell 1 of the embodiment includes the electrode 12 and the bipolar plate 2 facing one surface of the electrode 12, and is used as a main element of the RF battery 10.

The battery cell 1 of the embodiment is provided with one or more flow paths 3 (FIG. 2) in one or both of the electrode 12 and the bipolar plate 2. FIG. 2 and FIGS. 3 to 5 described later exemplify a case where the electrode 12 does not include the flow channel 3 and the bipolar plate 2 includes the flow channel 3. FIG. 6 illustrates a case where both the electrode 12 and the bipolar plate 2 include the flow path 3. The flow path 3 is provided continuously from the electrolyte supply edge 2i or 12i (FIG. 6) side toward the discharge edge 2o or 12o (FIG. 6) side. The battery cell 1 of the embodiment is provided with a specific set of channels 3 in which the volumes of the channels 3 adjacent to each other are different. Details of the flow path 3 will be described later. The cell stack 5 of the embodiment includes the battery cell 1 of the embodiment. The RF battery 10 of the embodiment includes the battery cell 1 of the embodiment or the cell stack 5 of the embodiment.

(Battery cell)
The battery cell 1 includes a positive electrode cell 1A and a negative electrode cell 1B. The positive electrode cell 1A includes a positive electrode 13 (an example of the electrode 12), a diaphragm 11, and a bipolar plate 2. The negative electrode cell 1B includes a negative electrode 14 (another example of the electrode 12), a diaphragm 11, and a bipolar plate 2. The electrode 12 is a reaction site where the active material (ions) contained in the positive electrode electrolytic solution or the negative electrode electrolytic solution causes a battery reaction. The bipolar plate 2 is a conductive member that allows an electric current to flow therethrough, and is a member that does not pass an electrolytic solution. The diaphragm 11 is a member that separates the positive electrode 13 and the negative electrode 14 and transmits predetermined ions. As the diaphragm 11, for example, an ion exchange membrane, a porous membrane or the like can be used.

When the RF battery 10 is a single cell battery, it has one positive electrode cell 1A and one negative electrode cell 1B. When the RF battery 10 is a multi-cell battery, it includes a plurality of sets of positive electrode cells 1A and negative electrode cells 1B. A multi-cell battery including a plurality of sets of positive electrode cells 1A and negative electrode cells 1B typically includes a cell stack 5. The battery cell 1 is typically constructed by using a cell frame 4 described later.

(RF battery)
The RF battery 10 is one of the electrolyte circulating type storage batteries. The RF battery 10 includes a battery cell 1 (may be the cell stack 5) and a circulation mechanism that supplies an electrolytic solution to the battery cell 1. RF battery 10 is typically connected to power generation unit 7 and load 8 via intervening device 6. Examples of the intervening device 6 include an AC/DC converter and a substation facility. Examples of the power generation unit 7 include a solar power generator, a wind power generator, and other general power stations. The load 8 may be, for example, a power system or a customer. The RF battery 10 is charged by using the power generation unit 7 as a power supply source and discharged by using the load 8 as a power supply target. The RF battery 10 is used for load leveling, voltage sag compensation, emergency power supply, smoothing output of natural energy power generation such as solar power generation and wind power generation.

<Circulation mechanism>
The circulation mechanism includes tanks 16 and 17, pipes 160 and 170 ( forward pipes 161, 171, return pipes 162, 172), and pumps 18, 19. The tank 16 stores a positive electrode electrolyte solution that is circulated and supplied to the positive electrode 13. The outward pipe 161 and the return pipe 162 connect between the tank 16 and the positive electrode cell 1A. The tank 17 stores a negative electrode electrolyte solution that is circulated and supplied to the negative electrode 14. The forward path 171 and the return path 172 connect between the tank 17 and the negative electrode cell 1B. The pumps 18 and 19 are respectively connected to the outward pipes 161 and 171 to circulate and supply the electrolytic solution to the positive electrode cell 1A and the negative electrode cell 1B. The black arrow in FIG. 1 illustrates the flow of the electrolytic solution.

<Electrolyte>
As the electrolytic solution, a solution containing ions serving as an active material can be used. Typically, an aqueous solution containing the above ions and an acid can be given. FIG. 1 illustrates an all-vanadium-based RF battery containing vanadium ions as positive and negative active materials. An electrolytic solution having a known composition such as a Mn—Ti-based RF battery containing manganese ions as the positive electrode active material and titanium ions as the negative electrode active material can be used.

<Cell frame>
The cell frame 4 includes the bipolar plate 2 and a frame body 40. The frame 40 is an electrically insulating member that supports the bipolar plate 2 and is used for supplying the electrolytic solution to the electrode 12 arranged on the bipolar plate 2 and for discharging the electrolytic solution from the electrode 12. In the cell frame 4 used at the end of the single cell battery or the multi-cell battery, the electrode 12 is arranged on one surface of the bipolar plate 2. In the cell frame 4 used in the middle part of the multi-cell battery, the positive electrode 13 is arranged on one surface and the negative electrode 14 is arranged on the other surface so as to sandwich both surfaces of one bipolar plate 2.

As shown in FIG. 2, the frame body 40 is provided so as to cover the region on the peripheral side of the bipolar plate 2. The frame body 40 includes a window portion 41 and a supply path and a discharge path for the electrolytic solution. The window portion 41 is provided in the central portion of the frame body 40 and exposes a region of the bipolar plate 2 where the electrode 12 is arranged. FIG. 2 illustrates a case where the frame body 40 has a rectangular outer shape and a rectangular window portion 41. The outer shape of the frame 40 and the shape of the window 41 can be changed as appropriate.

Typically, the frame body 40 has a positive electrode side supply passage and a discharge passage on one surface and a negative electrode side supply passage and a discharge passage on the other surface. The supply path includes liquid supply manifolds 43 (positive electrode) and 44 (negative electrode), slits from the liquid supply manifolds 43 and 44 to the window portion 41, and the like. The drainage passage includes drainage manifolds 45 (positive electrode) and 46 (negative pole), slits from the window 41 to the drainage manifolds 45 and 46, and the like. On the inner peripheral edge of the window portion 41 of the frame body 40, the opening portion of the slit of the supply passage and the vicinity thereof are used as the supply edge 2i of the electrolytic solution. On the inner peripheral edge of the window portion 41, the opening portion of the slit of the discharge passage and the vicinity thereof are used as the discharge edge 2o of the electrolyte. In addition, the frame body 40 of this example is provided with a sealing material 48, and liquid-tightly holds between the adjacent cell frames 4 (FIG. 1).

The constituent material of the frame body 40 may be a material having resistance to an electrolytic solution and electrical insulation, for example, a resin such as vinyl chloride resin. The frame 40 is, for example, a combination of divided pieces. The cell frame 4 can be constructed by combining the divided pieces so as to sandwich the bipolar plate 2 and appropriately joining them. Alternatively, the frame body 40 may be an integrally molded product by injection molding or the like. The cell frame 4 can be manufactured by molding the frame body 40 around the bipolar plate 2 by injection molding or the like.

(Cell stack)
The cell stack 5 typically includes a stack of a plurality of battery cells 1, a pair of end plates 51, and a fastening member 52. The above-mentioned laminated body is constructed by sequentially laminating the positive electrode cell 1A and the negative electrode cell 1B. Specifically, the laminated body includes a plurality of cell frames 4, and the cell frame 4 (bipolar plate 2), the positive electrode 13, the diaphragm 11, and the negative electrode 14 are sequentially laminated (see the exploded view of FIG. 2). .. Examples of the fastening member 52 include a connecting material such as a long bolt and a nut. By tightening the end plates 51 by the fastening members 52, the stacked body holds the stacked state by the tightening force in the stacking direction.

The cell stack 5 may include a plurality of sub cell stacks 50 as illustrated in FIG. The sub cell stack 50 includes a stack of a predetermined number of battery cells 1 and a pair of supply/discharge plates 53 sandwiching the stack. The above-mentioned pipes 160 and 170 are connected to the supply/discharge plate 53.

(Flow path)
Hereinafter, the flow path 3 will be described in detail with reference to FIGS. 3 to 6.
3 to 5 show only a part of the bipolar plate 2. FIG. 6 shows only part of the bipolar plate 2 and the electrodes 12.
3A, FIG. 3D, FIG. 3E, FIG. 4A, FIG. 4B, and FIG. 5A to FIG. 5C, FIG. 6 omits the region of the bipolar plate 2 on the peripheral side covered with the frame body 40. A part of an area exposed from the window 41 of the cell frame 4 (hereinafter referred to as an exposed area) is shown. The electrode 12 is arranged in this exposed area.
3B and 3C are examples of cross-sectional views taken along a plane that is parallel to the thickness direction of the bipolar plate 2 and that is orthogonal to the flow direction of the electrolytic solution along the shape of the flow path 3. Here is an example: The cutting of FIG. 3B corresponds to the case where the bipolar plate 2 is cut along the cutting line (B)-(B) shown in FIG. 3A.
FIG. 6 shows the electrode 12 and the bipolar plate 2 separated from each other so as not to overlap with each other so that the flow path 3 can be easily understood.

In the following description, in the peripheral edge of the electrode 12 and the peripheral edge of the exposed region of the bipolar plate 2, the portions used for supplying the electrolytic solution from the inner peripheral edge of the window 41 of the cell frame 4 are respectively the supply edges 12i of the electrode 12. , Feed edge 2i of the bipolar plate 2. In the peripheral edge of the electrode 12 and the peripheral edge of the exposed area of the bipolar plate 2, the portions used for discharging the electrolytic solution to the inner peripheral edge of the window 41 are the discharge edge 12o of the electrode 12 and the discharge edge 2o of the bipolar plate 2, respectively. Call.

3 to 6 exemplify a case where the planar shape of the electrode 12 and the planar shape of the exposed region of the bipolar plate 2 are rectangular. Further, in the plan views of FIGS. 3 to 5, the flow direction of the electrolytic solution in the bipolar plate 2 is a direction from the lower side to the upper side along the vertical direction of the paper surface. Of the peripheral edge of the exposed area, the lower edge extending linearly in the left-right direction of the drawing is a supply edge 2i and the upper edge is a discharge edge 2o. The flowing direction of the electrolytic solution here is a basic flowing direction of the electrolytic solution, and is not necessarily a direction along the shape of the flow path 3. When the supply edge 2i and the discharge edge 2o are arranged opposite to each other as in the present example, the flow direction of the electrolytic solution may be the direction of a straight line having the shortest distance between both edges. The planar shape of the exposed region, the arrangement positions of the supply edge 2i and the discharge edge 2o, the flowing direction of the electrolytic solution, and the like can be appropriately changed.

<Overview>
When the electrode 12 is provided with the flow path 3 in the battery cell 1 of the embodiment, the flow path 3 may be a groove that is open on the surface of the electrode 12 facing the bipolar plate 2. When the flow path 3 is provided in the bipolar plate 2, the flow path 3 may be a groove that opens on the surface of the bipolar plate 2 facing the electrode 12. When the electrode 12 or the bipolar plate 2 has a plurality of flow paths 3, it further has ridges 123 and 33 between the adjacent flow paths 3 (FIG. 6, FIG. 3A, etc.). The ridges 123 and 33 partition the flow path 3 and a portion other than the flow path 3. Since the battery cell 1 is provided with the flow path 3 such as the groove, the flowability of the electrolytic solution is excellent as compared with the case where the flow path 3 such as the groove is not provided. In the plan views of FIGS. 3 to 5, the ridges 33 are cross-hatched for easy understanding.

In particular, the battery cell 1 of the embodiment includes two channels 3 that are adjacent to each other in a plan view from the stacking direction of the electrode 12 and the bipolar plate 2. Of the two adjacent flow paths 3, at least one end of the flow path 3 opens at the supply edge or the discharge edge. FIG. 3A and the like exemplify a case where the bipolar plate 2 includes two or more flow paths 3 and one end of each flow path 3 is open to the supply edge 2i and the other end is open to the discharge edge 2o. Furthermore, in the battery cell 1 of the embodiment, the volumes of the two adjacent flow paths 3 are different. In the two flow passages 3 having different volumes, a state in which the pressure decreases when flowing through the flow passage 3, that is, a difference in the distribution of the pressure drop is likely to occur. As a result, a pressure difference is likely to occur in both flow paths 3. The battery cell 1 can promote the battery reaction by utilizing the pressure difference between the two flow paths 3 (details will be described later). Hereinafter, the two flow paths 3 that are arranged next to each other and have different volumes will be described more specifically.

<Form including two flow paths with different volumes>
The following modes (A) to (C) can be given as specific examples of the battery cell 1 that includes the two flow paths 3 that are arranged adjacent to each other and have different volumes. Either form may be used.
(A) The electrode 12 includes the two flow paths 3 having different volumes (not shown).
(B) The bipolar plate 2 includes the two flow paths 3 having different volumes (see FIGS. 3 to 5).
(C) The electrode 12 includes one of the two flow paths 3 having different volumes, and the bipolar plate 2 includes the other flow path 3 (see FIG. 6 ).

<How to change the volume>
As a method of changing the volumes of two adjacent flow paths 3, for example, the following modes (a) to (c) can be mentioned. Either form may be used.

(A) The groove depth of each flow path 3 is the same over the entire length of each flow path 3, and the groove width of each flow path 3 is different. The groove width here means the length of the opening of the flow path 3 (groove) in a cross section taken along a plane orthogonal to the flow direction of the electrolytic solution along the shape of the flow path 3. For example, when the flow channel 3 has a rectangular cross-sectional shape (eg, FIGS. 3B and 3C) and has a rectangular parallelepiped internal space, the groove width and the groove depth extend over the entire length of the flow channel 3. It is uniform.

In the form (a), typically, the groove width and the groove depth are constant (do not change) over the entire length of each flow path 3. In this case, as shown in the cross section of FIG. 3B, even if the groove depths d ₃ of both flow paths 3 ( linear grooves 34 and 35 described later in FIG. 3B) are equal, for example, one flow path 3 (in FIG. 3B, If the groove width W ₃₄ is wider than the groove width W _{35 of the} other flow path 3 (the straight groove 35 in FIG. 3B) over the entire length of the straight groove 34), the volume of one flow path 3 (the straight groove 34) is , Larger than the other flow path 3 (straight groove 35).

(B) The groove width of each flow path 3 is the same over the entire length of each flow path 3, and the groove depth of each flow path 3 is different. The groove depth here means from the opening edge of the channel 3 (groove) to the bottom of the channel 3 in a cross section taken along a plane orthogonal to the flow direction of the electrolytic solution along the shape of the channel 3. Maximum distance. When the groove width and the groove depth are constant over the entire length of each flow path 3 as described above, as shown in FIG. 3C, the groove width W ₃ of both flow paths 3 (the grooves 340 and 350 in FIG. 3C). Even if they are equal, for example, the groove depth d ₃₄ over the entire length of one flow path 3 (the groove 340 in FIG. 3C) is larger than the groove depth d _{35 of the} other flow path 3 (the groove 350 in FIG. 3C). If it is deep, the volume of one flow path 3 (groove 340) becomes larger than that of the other flow path 3 (groove 350).

(C) Both the groove width and the groove depth of one flow passage 3 are wider and deeper than the other flow passage 3 over the entire length of each flow passage (not shown). When the groove width and the groove depth are constant over the entire length of each flow path 3 as described above, one of the flow paths 3 has a larger groove width and groove depth than the other flow path 3. The volume of the one flow passage 3 is certainly larger than that of the other flow passage 3.

In the above (a) to (c), at least one of the groove width and the groove depth is not constant over the entire length of each flow path 3 and may be locally different (may vary). For example, when the groove depth is constant over the entire length of each flow path 3 and the groove width varies (see FIG. 5 ), the groove width of one flow path 3 extends over the entire length of the flow path 3. If the flow path is wider than the other flow path 3, the volume of one flow path 3 becomes larger than that of the other flow path 3. Alternatively, for example, when the groove width is constant over the entire length of each flow path 3 and the groove depth varies, the groove depth of one flow path 3 becomes equal to that of the other flow path 3 over the entire length of the flow path 3. If it is deeper than the flow passage 3, the volume of one flow passage 3 becomes larger than that of the other flow passage 3.

<Main action>
There is a difference in the distribution of the pressure drop when the electrolytic solution flows through each flow path 3, between the flow path 3 having a relatively large volume and the flow path 3 having a relatively small volume. Since the flow paths 3 are adjacent to each other, a pressure difference easily occurs between the flow paths 3. Due to this pressure difference, the flow of the electrolytic solution across the both flow paths 3 is likely to occur. Here, the electrolytic solution easily flows through the region of the electrode 12 that faces the ridge 33 provided between the flow paths 3. That is, the electrolytic solution easily spreads around the both flow paths 3 in the electrode 12 and is easily diffused in a wide range of the electrode 12. As a result, in the electrode 12, a battery reaction is likely to occur in a wider range, and the electrode 12 can perform a good battery reaction. Therefore, the battery cell 1 of the embodiment including the flow paths 3 having different volumes adjacent to each other can promote the battery reaction and contribute to the improvement of the efficiency of the battery reaction of the RF battery 10.

<Plan shape, etc.>
Mainly referring to FIGS. 3 to 6, the shapes of the above-described two flow paths 3 arranged side by side and having different volumes will be specifically described. In the following description, the form (B) in which the flow path 3 is provided in the bipolar plate 2 will be described as an example. When the bipolar plate 2 is replaced with the “electrode 12” in this description, it roughly corresponds to the form (A). After the description of the form (B), the form (C) in which the flow path 3 is provided in the electrode 12 and the bipolar plate 2 will be briefly described.

As an example of the above-mentioned adjacent flow paths 3, there is a form having the same planar shape but different groove widths. This form is an example of the form (a) described above. Further, FIG. 3 to FIG. 6 are all examples of this form. “The same planar shape but different groove widths” means that when the groove width of one flow path 3 is increased or decreased, the condition that it matches the outer shape of the other flow path 3 is satisfied. In such two flow paths 3, the shape of the portion of the peripheral edge of the flow path 3 that extends from the supply edge 2i side to the discharge edge 2o side has the same shape over the entire length of each flow path 3. For example, in the flow paths 3 shown in FIG. 4A, the shapes of the portions extending from the supply edge 2i side to the discharge edge 2o side at the peripheral edges of each flow path 3 are wave shapes having the same wavelength and the same phase and the same phase. ..

In the form in which the adjacent flow paths 3 have the same planar shape but different groove widths, the shapes of the adjacent flow paths 3 are simple as shown in FIGS. 3A, 4A, 5A, 6 and the like. Therefore, the bipolar plate 2 and the electrode 12 are easily formed, and the manufacturability of the bipolar plate 2 and the electrode 12 is excellent.

《Linear groove》
Hereinafter, description will be given mainly with reference to FIG.
A rectangular shape is an example of the planar shape of the flow path 3. Hereinafter, the flow path 3 having a rectangular planar shape will be referred to as a straight groove. 3A, FIG. 3B, FIG. 3D, and FIG. 3E exemplify the bipolar plate 2 provided with the linear grooves 34 and 35 as the above-mentioned two flow paths 3 that are adjacently arranged and have different volumes. 3A, FIG. 3B, FIG. 3D, and FIG. 3E exemplify the case where the groove width W ₃₄ of one straight groove ₃₄ is wider than the groove width W ₃₅ of the other straight groove 35. In each of the linear grooves 34 and 35 of this example, the long side direction is provided along the flow direction of the electrolytic solution (vertical direction on the paper surface), and the short side direction is the extending direction of the supply edge 2i and the discharge edge 2o ( It is provided along the horizontal direction of the paper). In this example, the groove widths and groove depths of the linear grooves 34 and 35 are constant over the entire length of the flow path 3, the groove depths of the linear grooves 34 and 35 are the same, and the groove widths of the linear grooves 34 and 35 are the same. The width is different.

The configuration in which the linear grooves 34 and 35 are provided as the flow path 3 facilitates the flow of the electrolytic solution through both flow paths 3 and is excellent in the flowability of the electrolytic solution. Further, the shapes of both flow paths 3 are simple. In addition, the planar shape of the ridge portion 33 provided between the flow paths 3 along the shape of the flow paths 3 (the linear grooves 34 and 35) is also rectangular, which is a simple shape. Therefore, the manufacturability of the bipolar plate 2 and the like is excellent. Further, the linear grooves 34 and 35 are line symmetrical with respect to the central axis of the flow path 3. Therefore, the volume of the flow path 3 can be easily changed by increasing or decreasing the groove widths W ₃₄ and W ₃₅ . The central axis of the channel 3 is a straight line connecting the bisectors of the width of the channel 3 over the entire length of the channel 3 in a plan view of the channel 3. Equivalent to.

The above-mentioned two flow paths 3 that are arranged next to each other and have different volumes may be the communication groove 30 (FIG. 3A) or the one-end closed groove 31 (FIGS. 3D and 3E). The communication groove 30 is a groove in which one end of the flow path 3 opens to the supply edge 2i and the other end opens to the discharge edge 2o. The one end closed groove 31 is a groove in which one end of the flow path 3 is opened to the supply edge 2i or the discharge edge 2o and the other end is not opened to both the supply edge 2i and the discharge edge 2o. The communication groove 30 has excellent electrolyte flowability. When the one-end closed groove 31 is provided, the part of the electrode 12 near the closed portion of the one-end closed groove 31 can be used as the utilization area, and the utilization area of the electrode 12 can be easily increased. Here, when the bipolar plate 2 is provided with the one-end blocking groove 31, the region from the end edge of the closed portion of the one-end blocking groove 31 to the supply edge 2i (FIG. 3D) or the discharge edge 2o (FIG. 3E) is The ridge 33. The electrode 12 can utilize a region facing the location 330 near the closed portion of the one-end closed groove 31 in the ridge 33 as a utilization region. In FIGS. 3D and 3E, and FIGS. 4B, 5B, and 5C described later, a portion 330 of the ridge portion 33 near the closed portion is surrounded by a chain double-dashed line and is virtually shown.

The position of the closed portion of the one-end closed groove 31 can be selected as appropriate. For example, the distance from the supply edge 2i to the discharge edge 2o in the bipolar plate 2 is L, and the distance from the closed portion to the supply edge 2i or the discharge edge 2o is L1, and the distance L1 is 1% or more and 20% or less of the distance L. Further, it may be 10% or less and 5% or less.

As shown in FIG. 3A, if the two flow channels 3 that are arranged adjacent to each other and have different volumes are the communication grooves 30, the flowability of the electrolytic solution is excellent. The bipolar plate 2 of this example is excellent in the flowability of the electrolytic solution also because it is provided with a plurality of sets of the linear grooves 34 and 35 as the flow path 3. The battery cell 1 having excellent flowability of the electrolytic solution also contributes to suppressing an increase in cell internal pressure (pressure loss) of the RF battery 10.

As shown in FIG. 3D and FIG. 3E, of the above-mentioned two adjacent flow paths 3, one flow path 3 is the communication groove 30, and the other flow path 3 is the one-end closed groove 31. The pressure difference between 30 and the one-end closed groove 31 is likely to be larger than when the communication grooves 30 are adjacent to each other. Therefore, the electrolytic solution flowing between the communication groove 30 and the one-end closed groove 31 is likely to increase. In this example, the electrolytic solution easily flows through the region of the electrode 12 that faces the ridge 33 provided between the communication groove 30 and the one-end closed groove 31. That is, the electrolytic solution easily spreads around the communication groove 30 and the one-end closed groove 31 of the electrode 12. By thus diffusing the electrolytic solution, the electrode 12 can favorably perform the battery reaction. Further, in this example, since the communication groove 30 is included, the flowability of the electrolytic solution is excellent. Since the communication groove 30 of this example is the straight groove 35, the flowability of the electrolytic solution is excellent. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10. The bipolar plate 2 of the present example includes the plurality of communication grooves 30 and the plurality of one-end closed grooves 31 as the flow path 3, and the communication grooves 30 and the one-end closed grooves 31 are alternately arranged, which promotes the battery reaction. easy.

As shown in FIG. 3D, if the closed portion of the one-end closed groove 31 of the bipolar plate 2 is located on the supply edge 2i side, the portion of the electrode 12 near the closed portion is the communication groove that is the other adjacent flow path 3. The electrolytic solution is easily supplied from 30. Also from this, the electrode 12 can favorably perform the battery reaction.

As shown in FIG. 3E, if the closed end of the one-end closed groove 31 is located on the discharge edge 2o side, a portion of the electrode 12 near the closed end easily discharges the reacted electrolytic solution to the adjacent communication groove 30. ..

When the two adjacent flow paths 3 include the communication groove 30 and the one end closed groove 31, the volume of the one end closed groove 31 is larger than the volume of the communication groove 30. That is, one flow path 3 having a large volume is the one end closed groove 31. 3D, the in FIG. 3E, the groove width _{W 34} is relatively large linear grooves 34, that is, thick straight groove 34 and one end closed groove 31, the groove width _{W 35} is relatively small straight grooves 35, i.e. a thin linear groove Reference numeral 35 is a communication groove 30. In the configuration including the one-end closed groove 31, as described above, the electrode 12 can use the portion 330 near the closed portion of the one-end closed groove 31 as the utilization region. Further, since the one-end closed groove 31 has a relatively large volume, it is easier to increase the contact area with the electrolytic solution than the communication groove 30. Therefore, in this mode, it is easy to secure a larger utilization area of the electrode 12, and the electrode 12 can perform a favorable battery reaction. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10.

The volume of the one-end closed groove 31 may be smaller than the volume of the communication groove 30. In this case, even if the flow rate of the electrolytic solution flowing through the one-end closed groove 31 is relatively smaller than that in the communication groove 30, the distribution of the pressure drop when the electrolytic solution flows through the one-end closed groove 31 is the communication groove. The volume of each groove is adjusted so as not to be extremely different from the distribution of the pressure drop when flowing through 30. By doing so, the distribution of the flow of the electrolytic solution that diffuses into the electrode 12 can be easily made uniform, and the electrode 12 can perform a favorable battery reaction.

"Groove width"
In a configuration in which adjacent flow paths 3 have the same planar shape but different groove widths, the groove width and the groove depth are constant over the entire length of both flow paths 3 as described above, and the groove depths of both flow paths 3 are the same. 3B, the groove width W ₃₄ of the one flow path 3 (straight groove 34) may be wider than the groove width W ₃₅ of the other flow path 3 (W ₃₅ <W ₃₄ ). In this case, the size ratio of the groove widths W ₃₄ and W ₃₅ is the volume ratio. For example, the volume (or groove width) of one flow path 3 having a large volume may be 1.2 times or more and 5 times or less the volume (or groove width) of the other flow path 3. In this case, the volume of each flow path 3 can be easily changed by adjusting the groove width of each flow path 3. If the groove width is constant over the entire length of each flow path 3 as in this example (where W ₃₅ <W ₃₄ ), the width of the ridge portion 33 between both flow paths 3 also extends over the entire length of the flow path 3. The width of the ridge 33 is easy to adjust.

《Groove depth》
In a configuration in which adjacent flow paths 3 have the same planar shape but different groove widths, the groove depths of both flow paths 3 may be different (not shown). In this case, the groove depth may be adjusted according to the groove width of each channel 3 so that the volumes of both channels 3 are different.

《Meandering groove》
Hereinafter, description will be given mainly with reference to FIG.
As another example of the planar shape of the flow path 3, a meandering shape can be cited. Hereinafter, the flow path 3 having a meandering planar shape will be referred to as a meandering groove. 4A and 4B exemplify the bipolar plate 2 including the meandering grooves 36 and 37 as the above-mentioned two flow paths 3 arranged side by side and having different volumes. 4A and 4B exemplify a case where the groove width W ₃₆ of the one meandering groove ₃₆ is wider than the groove width W ₃₇ of the other meandering groove 37. Each of the meandering grooves 36 and 37 of this example has a curved wave shape (for example, a sine wave shape), and the longitudinal direction is provided substantially along the flowing direction of the electrolytic solution (vertical direction on the paper surface). In this example, the groove widths and groove depths of the meandering grooves 36 and 37 are constant over the entire length of the flow path 3, the groove depths of the meandering grooves 36 and 37 are the same, and the groove widths of the meandering grooves 36 and 37 are the same. The widths are different (W ₃₇ <W ₃₆ ).

The configuration in which the meandering grooves 36 and 37 are provided as the flow path 3 makes it easier to increase the utilization area of the electrode 12 than in the case of the above-described linear groove, and the electrode 12 can perform the battery reaction better. In the meandering grooves 36 and 37, the friction between the electrolytic solution flowing in the meandering grooves 36 and 37 and the inner side wall forming the meandering grooves 36 and 37 changes according to the flow direction of the electrolytic solution in the meandering grooves 36 and 37. Due to this change, in the adjacent meandering grooves 36 and 37, the above-mentioned difference in pressure drop distribution, and thus the pressure difference, is likely to occur. As a result, the meandering grooves 36 and 37 easily promote the diffusion of the electrolyte solution around the meandering grooves 36 and 37. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10.

　The serpentine shape can be changed to a serpentine shape (triangular wave shape), a rectangular wave shape, a sawtooth shape (right angle triangular wave shape), etc. in addition to a curved wave shape. Further, the meandering grooves 36 and 37 can increase the contact area with the electrolytic solution by increasing the meandering amplitude and/or increasing the number of peaks (valleys). Therefore, the utilization area of the electrode 12 can be easily increased, and the electrode 12 can perform the battery reaction better. The planar shape of the meandering grooves 36, 36 is asymmetrical about the central axis of the flow path 3.

For the same reason, the meandering grooves 36 and 37 may be the communicating groove 30 or the one-end closed groove 31 as described in the section of the straight groove. FIG. 4A illustrates a case where both the meandering grooves 36 and 37 are the communication grooves 30. In this case, the flowability of the electrolytic solution is excellent as described above. In FIG. 4B, one meandering groove 36 having a relatively large volume (groove width W ₃₆ ), that is, the thicker meandering groove 36 is the one end closing groove 31, and the other meandering groove 37, that is, the thinner meandering groove 37 is the communication groove 30. The case will be exemplified. In this case, as described above, the electrolytic solution easily spreads around the meandering grooves 36 and 37, and the electrolytic solution is diffused, so that the electrode 12 can perform a favorable battery reaction. In addition, the planar shape of the ridge portion 33 provided between the adjacent flow paths 3 is a meandering shape along the shape of both the flow paths 3 (the meandering grooves 36 and 37).

Although FIG. 4B and FIGS. 5B and 5C described later exemplify the case where the closed end of the one-end closed groove 31 is located on the supply edge 2i side, it may be located on the discharge edge 2o side (as a similar shape, FIG. 3E). reference). For other matters relating to the position of the closed portion, the groove width, the groove depth, etc., refer to the item of the linear groove described above.

<<Repeated groove with a predetermined shape>>
Hereinafter, description will be given mainly with reference to FIG.
Still another example of the planar shape of the flow path 3 is a shape in which the groove width changes periodically in the longitudinal direction of the flow path 3. Hereinafter, this flow path 3 is referred to as a repeating groove having a predetermined shape. 5A to 5C exemplify the bipolar plate 2 having the repetitive grooves of a predetermined shape as the above-described two flow passages 3 arranged side by side and having different volumes. In addition, FIGS. 5A to 5C illustrate double-edged saw-tooth saw blade grooves 38 and 39 that are formed by stacking a plurality of trapezoids, as an example of a repeating groove having a predetermined shape. Further, FIGS. 5A to 5C exemplify a case where the maximum groove width W ₃₈ of the one saw blade groove ₃₈ is wider than the maximum groove width W ₃₉ of the other saw blade groove 39 (W ₃₉ <W ₃₈ ). In the saw blade grooves 38 and 39 of this example, the longitudinal direction is provided along the flowing direction of the electrolytic solution (vertical direction on the paper surface). In this example, the groove depths of the saw blade grooves 38 and 39 are constant over the entire length of the flow path 3, the groove depths of the saw blade grooves 38 and 39 are the same, and the groove depths of the saw blade grooves 38 and 39 are the same. A case where the width fluctuates within a predetermined range will be exemplified.

The repetitive groove having a predetermined shape is more likely to increase the utilization area of the electrode 12 than in the case of the straight groove, and the electrode 12 can perform the battery reaction better. In the repetitive groove having a predetermined shape, the friction between the electrolytic solution flowing in the groove and the inner wall forming the groove changes according to the flow direction of the electrolytic solution in the groove. When the repetitive grooves having a predetermined shape are adjacent to each other, a difference in the above-described pressure drop distribution is likely to occur in both grooves due to the above change. As a result, the repeating groove having the predetermined shape facilitates the diffusion of the electrolyte solution around the groove.

Further, in the repeating groove having the predetermined shape, the groove width changes in the longitudinal direction, and thus the state of pressure decrease in the flow direction of the electrolytic solution in the groove changes periodically. Here, the pressure reduction state periodically changes in accordance with the change in the groove width from the supply edge 2i side toward the discharge edge 2o side. At a portion where the groove width is relatively wide, the pressure drop is relatively small, and the flow rate of the electrolytic solution flowing in the groove is relatively slow. At a portion where the groove width is relatively narrow, the pressure drop is relatively large and the flow velocity is relatively fast. The portions having different pressure reduction states (flow velocities) are alternately arranged from the supply edge 2i side to the discharge edge 2o side. In the saw blade grooves 38 and 39 shown in FIG. 5A, a portion where the groove width is continuously narrowed and a portion where the groove width is rapidly widened are repeatedly arranged from the supply edge 2i side toward the discharge edge 2o side.

When the repetitive grooves of a predetermined shape are adjacent to each other, the volumes of both grooves are different, so the phase of the cycle related to the above-mentioned pressure drop distribution is shifted. Due to the phase shift of this cycle, the pressure difference between both grooves becomes large. Then, the electrolytic solution flowing between the both grooves tends to increase. That is, the electrolytic solution is easily diffused so as to spread around the both grooves. From these things, the electrode 12 can utilize the circumference|surroundings of the repeating groove of a predetermined shape as a utilization area|region.

The configuration including the repeating groove having the predetermined shape can promote the diffusion of the electrolyte solution around the repeating groove having the predetermined shape, as compared with the case of the linear groove, and the area where the electrode 12 is used is easily increased, so that the electrode 12 is a battery. The reaction can be performed better. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10.

If the plane shape of the repeating groove having a predetermined shape is a double-edged saw blade groove 38, 39 as illustrated in FIG. 5A or the like, a change in the flow velocity in the flow direction of the electrolytic solution in the saw blade groove 38, 39. Is large, and the change in the pressure drop state tends to be large. When the saw blade grooves 38 and 39 are adjacent to each other, the pressure difference between the saw blade grooves 38 and 39 is likely to be larger. Therefore, the electrolytic solution flowing between the saw blade grooves 38 and 39 is likely to increase. In this example, the electrolytic solution easily flows through the region of the electrode 12 that faces the ridge 33 provided between the saw blade grooves 38 and 39. That is, the electrolytic solution easily spreads around the saw blade grooves 38 and 39 of the electrode 12. In addition, the saw blade grooves 38 and 39 have a shape in which the groove width is relatively wide and the portion where the flow velocity is relatively slow is angular. In FIG. 5A and the like, the places where the maximum groove widths W ₃₈ and W ₃₉ are taken are square. Since the electrolytic solution is likely to temporarily stay in such an angular portion, the electrolytic solution is likely to diffuse into the electrode 12. By thus diffusing the electrolytic solution, the electrode 12 can perform a good battery reaction. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10.

The planar shape of the repeating groove of a predetermined shape is a double-edged saw shape, a single-edged saw shape that stacks multiple right-angled trapezoids, a chain shape that connects multiple circles, or a rectangle sandwiched between circles and circles. , A skewered shape in which circles and rectangles are alternately arranged, a hammer shape in which wide rectangles and narrow rectangles are alternately arranged, and the like. The groove width of one flow path 3 may have a portion that continuously changes as in the present example, or may have a portion that changes intermittently (eg, the hammer shape). Further, by increasing the number of repeating shapes and/or increasing the maximum groove width, it is possible to promote more even diffusion of the electrolytic solution in the electrode 12. Therefore, the utilization area of the electrode 12 can be easily increased, and the electrode 12 can perform the battery reaction better. The variation range of the groove width of the repeating groove having a predetermined shape can be appropriately selected. It is advisable to adjust the variation range of the groove width of each adjacent flow passage 3 so that the volume of one flow passage 3 becomes relatively large. If the minimum value of the fluctuation range of the groove width in one flow path 3 is equal to or larger than the maximum value of the groove width range in the other flow path 3, the volume of one flow path 3 becomes relatively large. If the volume of one flow path 3 becomes relatively large, the minimum value of the variation range of the groove width in one flow path 3 may be included in the range of the groove width in the other flow path 3. In addition, the planar shape of the repeating groove having a predetermined shape may be symmetrical with respect to the central axis of the flow path 3 illustrated in FIG. 5A or the like, or may be asymmetrical (for example, a single-edged sawtooth shape).

For the same reason, the repeating groove having the predetermined shape may be the communicating groove 30 or the one-end closed groove 31, as described in the above-mentioned straight groove. FIG. 5A illustrates the case where the both saw blade grooves 38, 39 are the communication grooves 30. In this case, the flowability of the electrolytic solution is excellent as described above. 5B and 5C, one saw blade groove 38 having a relatively large volume (maximum groove width W ₃₈ ), that is, a thick saw blade groove 38 is one closed groove 31 and the other saw blade groove 39 is thin. A case where the saw blade groove 39 is the communication groove 30 will be exemplified. In this case, as described above, the electrolytic solution easily spreads around the saw blade grooves 38, 39, and the electrolytic solution is diffused so that the electrode 12 can perform a favorable battery reaction. In addition, the planar shape of the ridge portion 33 provided between the adjacent flow paths 3 is a shape in which predetermined shapes are repeatedly arranged corresponding to the shapes of both the flow paths 3 (saw blade grooves 38, 39 ). In FIGS. 5A and 5B, the planar shape of the ridge portion 33 is a double-edged saw shape in which the direction of the saw blade is opposite to the saw blade grooves 38, 39.

5A and 5B exemplify a case where the saw blades in adjacent flow paths 3 (saw blade grooves 38, 39) have the same orientation. As shown in FIG. 5C, the direction of the saw blade may be reversed. The pressure difference between the saw blade grooves 38 and 39 is large because the difference in the distribution of the pressure drop in the saw blade grooves 38 and 39 (the change in the pressure drop state) is large and the direction of the saw blade is opposite. It tends to grow even larger. Therefore, the electrolytic solution flowing between the saw blade grooves 38 and 39 is likely to increase further. As a result, the electrolyte solution is more likely to diffuse around the saw blade grooves 38, 39 in the electrode 12 and diffuse more. Since the electrolytic solution is diffused into a wider area of the electrode 12, the electrode 12 can perform the battery reaction better. Such a battery cell 1 contributes to further improvement in the efficiency of the battery reaction of the RF battery 10.

Further, if the saw blades are oriented in the opposite direction, it is easy to make the interval between the adjacent saw blade grooves 38, 39 uniform from the supply edge 2i side to the discharge edge 2o side. FIG. 5C exemplifies a case where the planar shape of the ridge portion 33 provided between the saw blade grooves 38 and 39 is a shape in which a plurality of parallelograms are shifted and stacked. The interval between the saw blade grooves 38, 39 corresponds to the width of the ridge portion 33 provided between the saw blade grooves 38, 39. Further, it can be said that the width of the ridge portion 33 corresponds to the width of the utilization region of the electrode 12. Therefore, the electrode 12 can have a utilization region having a uniform width between the adjacent saw blade grooves 38 and 39, and it is easy to uniformly and stably perform the battery reaction. Further, when the saw blades are oriented in the opposite direction (FIG. 5C), the interval between the adjacent saw blade grooves 38 and 39 is easily narrowed compared to when the saw blades are oriented in the same direction (FIGS. 5A and 5B). .. As a result, when the saw blade is oriented in the opposite direction, it is easy to have more flow passages 3, and thus the flowability of the electrolytic solution can be further enhanced.

<Other forms>
FIG. 6 shows the above-mentioned form (C). As shown in FIG. 6, the battery cell 1 according to the embodiment includes one of the two flow passages 3 which are arranged adjacent to each other and have different volumes, in the electrode 12 and the other flow passage 3. It may be provided in the bipolar plate 2. In this case, the formation position of the flow path 3 of the electrode 12 and the formation position of the flow path 3 of the bipolar plate 2 are such that the electrode 12 and the bipolar plate 2 are overlapped with each other and the flow of the electrode 12 in a plan view from the stacking direction thereof. The path 3 (the linear groove 35 in FIG. 6) and the flow path 3 of the bipolar plate 2 (the linear groove 34 in FIG. 6) are adjusted to be adjacent to each other. In FIG. 6, the position of the flow path 3 (the linear groove 35) of the electrode 12 in the bipolar plate 2 is virtually shown by a chain double-dashed line. The flow path 3 of the electrode 12 is arranged in the ridge portion 33 between the flow paths 3 of the bipolar plate 2.

In FIG. 6, the linear grooves 34 and 35 that are the communication grooves 30 are illustrated as the respective flow paths 3, but the meandering grooves 36 and 37 or the saw blade grooves 38 and 39 may be changed. One of the flow paths 3 may be changed to the closed groove 31 at one end. Further, in FIG. 6, a case where the electrode 12 has the relatively thin linear groove 35 and the bipolar plate 2 has the relatively thick linear groove 34 is illustrated, but they may be reversed.

The electrode 12 of this example is provided with a plurality of linear grooves 35 at equal intervals in the extending direction of the supply edge 12i or the discharge edge 12o. The bipolar plate 2 of this example is provided with a plurality of straight grooves 34 at equal intervals in the extending direction of the supply edge 2i or the discharge edge 2o. In the electrode 12, the interval between the adjacent linear grooves 35 is adjusted so that one linear groove 34 of the bipolar plate 2 is interposed between the adjacent linear grooves 35. The ridges 123 are provided between the adjacent linear grooves 35 of the electrode 12. The ridges 123 of the electrode 12 are arranged to face the openings of the linear grooves 34 of the bipolar plate 2. In such a form, the electrolytic solution is easily supplied to the ridge portion 123 between the linear groove 35 (flow channel 3) of the electrode 12 and the linear groove 34 (flow channel 3) of the bipolar plate 2 in the electrode 12. Therefore, the electrode 12 is more efficiently supplied with the electrolytic solution and is more likely to cause a battery reaction.

<Bipolar plate material>
Examples of the constituent material of the bipolar plate 2 include organic composite materials, so-called conductive plastics, and the like. Examples of the organic composite material include those containing a conductive material such as a carbon-based material or a metal, and an organic material such as a thermoplastic resin. The bipolar plate 2 may be formed into a plate shape by a known method, for example. Examples of the method for molding the conductive plastic include injection molding, press molding, vacuum molding and the like. When the bipolar plate 2 is provided with the flow path 3, the flow path 3 may be formed at the same time when it is formed into a plate shape. Alternatively, the flow path 3 may be formed by performing a cutting process or the like on a flat plate material.

<Constituent material of electrode>
The electrode 12 is typically a fiber assembly of carbon material. Examples of the fiber aggregate of carbon material include carbon felt, carbon paper, and carbon cloth. A known electrode material may be used. When the electrode 12 is provided with the flow path 3, it is possible to form the flow path 3 at the same time when it is formed into a plate shape.

(Main effect)
In the battery cell 1 of the embodiment, one or both of the electrode 12 and the bipolar plate 2 are provided with a specific set of flow paths 3 in which the flow paths 3 having different volumes are arranged adjacent to each other, thereby promoting diffusion of the electrolytic solution. it can. Such a battery cell 1 can promote the battery reaction and can construct the RF battery 10 that can efficiently perform the battery reaction.

Since the cell stack 5 of the embodiment includes the battery cell 1 of the embodiment, the RF battery 10 that can promote the battery reaction and can efficiently perform the battery reaction can be constructed.

Since the RF battery 10 of the embodiment includes the battery cell 1 of the embodiment or the cell stack 5 of the embodiment, the battery reaction can be promoted and the battery reaction can be efficiently performed.

The present invention is not limited to these exemplifications, and is shown by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope. For example, at least one of the following modifications can be made to the battery cell 1 of the embodiment.

(Modification 1) Two flow passages 3 arranged adjacent to each other and having different volumes have the same planar shape, the groove width is the same over the entire length of both flow passages 3, and the groove depth of each flow passage 3 is the same. Are different (see FIG. 3C). In this embodiment, as shown in FIG. 3C, the groove depth d ₃₄ of one flow path 3 (groove 340) may be deeper than the groove depth d _{35 of the} other flow path 3 (groove 350) (d ₃₅ < d _34). In this case, the ratio of the sizes of the groove depths d ₃₄ and d ₃₅ is the ratio of volume. For example, the volume (or groove depth) of one flow path 3 having a large volume may be 1.2 times or more and 5 times or less the volume (or groove depth) of the other flow path 3.

(Modification 2) Two flow paths 3 arranged adjacent to each other and having different volumes have different planar shapes. For example, one flow path 3 may be a straight groove and the other flow path 3 may be a meandering groove or a saw blade groove. Alternatively, for example, one channel 3 may be a meandering groove and the other channel may be a saw blade groove. It can be said that this form includes at least one of the electrode 12 and the bipolar plate 2 including the flow path 3 having different planar shapes.

(Modification 3) The planar shapes of the two flow paths 3 arranged adjacent to each other and having different volumes are shapes other than a rectangle, a meandering shape, and a saw shape.

(Modification 4) When the electrode 12 is provided with the flow path 3, it includes a groove that is not opened in both the supply edge 12i and the discharge edge 12o. When the flow path 3 is provided in the bipolar plate 2, a groove that does not open is provided in both the supply edge 2i and the discharge edge 2o.

(Modification 5) The planar shape of the electrode 12 and the planar shape of the exposed region of the bipolar plate 2 are changed.
Examples of the planar shape include an ellipse shape, a racetrack shape, and the like, at least a part of which includes a curve, and a hexagonal shape, an octagonal shape, and the like. Also in this case, as described above, the portions of the peripheral edge of the electrode 12 and the peripheral edge of the bipolar plate 2 which are in contact with the inner peripheral edge where the slit of the supply path in the cell frame 4 is opened are defined as the supply edges 12i and 2i. It is advisable to use the discharge edges 12o and 2o as the portions in contact with the inner peripheral edge where the slits of the discharge path are open.

(Modification 6) The flow path 3 includes a rectifying groove.
When at least one of the electrode 12 and the bipolar plate 2 is provided with the flow path 3, the flow path 3 is a rectifying groove provided along the extending direction of the supply edge and a rectifying groove provided along the extending direction of the discharge edge. May be included. When the flow path 3 includes a rectifying groove, it is preferable that an end of the communication groove 30 and one end of the one-end closing groove 31 be opened to the rectifying groove. Instead of providing the electrode 12 or the bipolar plate 2 with the rectifying groove, the rectifying groove may be provided along the inner peripheral edge of the window portion 41 of the cell frame 4.

10 Redox flow battery (RF battery)
DESCRIPTION OF SYMBOLS 1 battery cell, 1A positive electrode cell, 1B negative electrode cell 11 diaphragm, 12 electrode, 13 positive electrode, 14 negative electrode 12i supply edge, 12o discharge edge, 123 ridge section 16,17 tank, 160,170 piping 161,171 forward piping, 162,172 Return pipe, 18,19 Pump 2 Bipolar plate 2i Supply edge, 2o Discharge edge 3 Flow path 30 Communication groove, 31 One end closed groove, 33 Ridge portion 34,35 Straight groove, 36,37 Meandering groove, 38,39 Saw blade groove 330 Location near the closed end of the one-end closed groove in the ridge portion 340,350 groove 4 cell frame 40 frame body, 41 window portion, 43,44 liquid supply manifold 45,46 drainage manifold, 48 sealing material 5 cell stack 50 sub-cell stack, 51 end plate, 52 fastening member 53 supply/discharge plate 6 intervening device, 7 power generation part, 8 load

Claims (12)

1. A battery cell comprising an electrode and a bipolar plate facing one surface of the electrode,
   One or both of the electrode and the bipolar plate are provided with one or more flow passages continuously provided from the supply edge side of the electrolytic solution toward the discharge edge side,
   Of the two flow channels adjacent to each other in a plan view from the stacking direction of the electrode and the bipolar plate, at least one end of the flow channel has an opening at the supply edge or the discharge edge, and the adjacent flow channels. Have different volumes,
   Battery cell.
2. The battery cell according to claim 1, wherein the adjacent channels have the same planar shape but different groove widths.
3. The battery cell according to claim 2, wherein the planar shape of the flow path is a rectangular shape or a meandering shape.
4. The battery cell according to claim 2, wherein the planar shape of the flow path is a shape in which a groove width periodically changes in a longitudinal direction of the flow path.
5. The battery cell according to claim 4, wherein the planar shape is a double-edged saw shape.
6. The battery cell according to claim 5, wherein the saw blades in the adjacent flow paths have opposite directions.
7. Of the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is The one end of the flow path is a one-end closed groove that is open to the supply edge or the discharge edge and the other end is not opened to both the supply edge and the discharge edge. Battery cell.
8. The adjacent channels have the same planar shape but different groove widths,
   The planar shape of the flow path is a meandering shape,
   Further, among the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is The battery cell according to claim 1, wherein one end of the flow path is a one-end closed groove that opens at the supply edge or the discharge edge and the other end does not open at both the supply edge and the discharge edge.
9. The adjacent channels have the same planar shape but different groove widths,
   The planar shape is a double-edged saw shape,
   Further, among the adjacent flow paths, one of the flow paths is a communication groove in which one end of the flow path is open to the supply edge and the other end is open to the discharge edge, and the other flow path is The battery cell according to claim 1, wherein one end of the flow path is a one-end closed groove that opens at the supply edge or the discharge edge and the other end does not open at both the supply edge and the discharge edge.
10. The battery cell according to any one of claims 7 to 9, wherein a volume of the one end closed groove is larger than a volume of the communication groove.
11. A battery cell according to any one of claims 1 to 10 is provided,
    Cell stack.
12. A battery cell according to any one of claims 1 to 10 or a cell stack according to claim 11,
    Redox flow battery.

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