JP2012146469A - Redox flow battery, redox flow battery cell, and cell stack for redox flow battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a redox flow battery (RF battery) in which electrolyte solution flows easily and uniformly into an electrode, and to provide an RF battery cell suitable for the configuration member of this battery, and a cell stack for the RF battery.SOLUTION: The RF battery comprises a cell stack where a battery cell 10 including a positive electrode 14 to which a positive electrode electrolyte is distributed, a negative electrode 15 to which a negative electrode electrolyte is distributed, and a barrier membrane 101 interposed between both electrode 14, 15, and a frame 12 having a bipolar plate 121 are stacked alternately. Both electrode 14, 15 consist, respectively, of an electrode 1A where a plurality of distribution grooves (lateral grooves) 2A are provided in parallel to intersect the distribution direction of the electrolyte substantially perpendicularly. Since the distribution grooves (lateral grooves) 2A exist to block the flow of the electrolyte, the passing electrolyte is reduced effectively without contributing to the battery reaction.

Description

  The present invention relates to a redox flow battery (hereinafter sometimes referred to as an RF battery), an RF battery cell stack suitable for a component of the RF battery, and an RF battery cell. In particular, the present invention relates to an RF battery in which an electrolytic solution easily flows in an electrode.

  RF batteries are used as large-capacity storage batteries for the purpose of instantaneous voltage drop, power failure countermeasures, and load leveling. In addition, RF batteries are expected as storage batteries for the purpose of smoothing output fluctuations, storing surplus power, leveling loads, etc., for new energy such as solar power generation and wind power generation.

  The RF battery 100 is typically configured as shown in FIG. 5, and includes a positive electrode cell 102 incorporating a positive electrode 104, a negative electrode cell 103 incorporating a negative electrode 105, and both cells 102, 103 interposed between both cells 102, 103. A cell is provided that includes a diaphragm 101 that separates and transmits ions. In addition, the RF battery 100 stores the electrode electrolytes 106 and 107 that store the electrode electrolytes used for the battery reaction in the electrode cells 102 and 103, and distributes the electrolyte solution between the electrode cells 102 and 103 and the electrode tanks 106 and 107. The pipes 108 to 111 are provided. The electrode electrolytes are circulated and supplied to the electrode cells 102 and 103 by using pumps 112 and 113 installed in the pipes 108 and 109, respectively. As the electrolytic solution, an aqueous solution containing a metal ion whose valence is changed by oxidation-reduction, for example, vanadium ion is used. In addition, the solid line arrow in the cell of FIG. 5 means charging, and the broken line arrow means discharging.

  The RF battery 100 typically uses a form called a cell stack in which a plurality of the cells are stacked (see FIG. 9 of Patent Document 1). For the cell stack 200, a frame 122 shown in FIG. 6 is used. The frame 122 is provided on the outer periphery of the bipolar plate 121 where the electrode electrodes 104 and 105 are arranged on the front and back sides. The cell stack 200 is repeatedly laminated in order of a frame 122 having a bipolar plate 121, a positive electrode 104, a diaphragm 101, a negative electrode 105, a frame 122 having a bipolar plate 121, etc. It is configured by sandwiching between a pair of end plates 210 and tightening the end plate 210 with a tightening member 220 such as a long bolt.

  The frame 122 is provided on one surface of the electrode electrolyte supply holes 123 and 124 and the drain holes 125 and 126 penetrating the front and back surfaces thereof, and is continuous with the liquid introduction groove and the drain hole 125 that are continuous with the liquid supply hole 123. A liquid discharge groove, a liquid introduction groove provided on the other surface and continuous with the liquid supply hole 124 and a liquid discharge groove continuous with the liquid discharge hole 126 are provided. Using the liquid introduction groove / liquid discharge groove, the positive electrode electrolyte is supplied to and discharged from the positive electrode 104 disposed on one surface of the bipolar plate 121, and the negative electrode electrolyte is supplied to the negative electrode 105 disposed on the other surface.・ It is discharged. By laminating a plurality of frames 122, the liquid supply hole 123 (124) and the drainage hole 125 (126) constitute a flow path for each electrolytic solution, and this flow path is appropriately connected to the pipes 108 to 111. . In addition, a seal member 127 such as an O-ring is disposed between the stacked frames 122 to prevent leakage of the electrolyte solution from the gaps between the above members that constitute the cell stack 200.

  In the frame 122, a configuration in which a rectifying groove (not shown) connected to the liquid introduction groove and the liquid discharge groove is provided along the peripheral edge in each of the opposing peripheral side regions of the rectangular bipolar plate 121 is typical. Yes (see FIGS. 1 and 2 of Patent Document 1). The rectifying groove has a function of expanding the electrolytic solution from the liquid introducing groove along the peripheral edge and concentrating the electrolytic solution from the electrode into the liquid discharging groove.

  For each electrode 104, 105, carbon felt made of carbon fiber is used (Patent Documents 1, 2). In Patent Document 2, as shown in Fig. 6, the flow direction of the electrolyte solution (the direction connecting the opposite sides of the rectangular electrode on one side of the electrode (the surface on the side of the diaphragm 101 in Patent Document 2). And a plurality of flow grooves 104s provided in parallel to (direction).

Japanese Patent Laid-Open No. 2002-367659 Japanese Patent Laid-Open No. 2002-246035

  In the RF battery, it is desired that the electrolytic solution easily flows uniformly in the electrode, and that the electrolytic solution can sufficiently perform a battery reaction in the electrode.

  As described above, in an electrode having a plurality of flow grooves (hereinafter referred to as vertical grooves) parallel to the flow direction of the electrolytic solution (hereinafter referred to as vertical grooves), the electrolyte easily flows through the vertical groove portion. As compared with an electrode having a uniform surface not subjected to groove processing (hereinafter referred to as a grooveless electrode), pressure loss of the electrode and variation in pressure applied to the electrode can be reduced. Therefore, it is easy to make the flow of the electrolyte uniform over the entire electrode. Further, in this electrode, since the pressure loss is mainly determined by the cross-sectional shape of the flow groove, it is easy to control the flow rate distribution of the electrolytic solution in the electrode (to easily reduce the variation in flow rate).

  However, since the electrolytic solution flows more easily in the flow groove (vertical groove) portion than in other portions of the electrode, the electrolytic solution may pass without contributing to the battery reaction. Therefore, internal resistance (electrical resistance in the battery) may increase.

  In addition, if there is a defect such as clogging of the distribution groove (vertical groove) due to long-term use or formation failure of the groove, the electrolyte may flow to another distribution groove other than the groove having this defect. There is sex. If a region where the electrolytic solution flows excessively in a part of the electrode is generated, the electrolytic solution may be less likely to flow than the grooveless electrode in a region downstream of the defective portion. As a result of the difference in the flow of the electrolyte, the active material is insufficient and overcharge occurs at the location where the flow of the electrolyte is slow. Oxygen is generated at the positive electrode and hydrogen is generated at the negative electrode due to this overcharge side reaction. there's a possibility that. The oxygen may oxidize the constituent members of the RF battery including the electrodes, and may cause the life of these constituent members to be shortened.

  Accordingly, one of the objects of the present invention is to provide an RF battery in which an electrolyte can easily flow uniformly in an electrode and a battery reaction can be sufficiently performed. Another object of the present invention is to provide an RF battery cell and an RF battery cell stack suitable for the constituent members of the RF battery.

  The present invention achieves the above-mentioned object by making the forming direction of the flow grooves provided in the electrodes different from those of the conventional vertical grooved electrodes.

  The redox flow battery cell of the present invention includes a positive electrode through which a positive electrode electrolyte is circulated, a negative electrode through which a negative electrode electrolyte is circulated, and a diaphragm interposed between these two electrodes. The electrode has at least one electrolyte flow channel on its surface. At least one of the flow grooves is a horizontal groove provided so that the longitudinal direction thereof is substantially perpendicular to the flow direction of the electrolyte solution.

  The cell stack for the redox flow battery of the present invention is formed by alternately stacking a plurality of the above-described redox flow battery cells of the present invention and the following frames. This frame is provided on the outer periphery of a bipolar plate in which each electrode provided in the battery cell is arranged on the front and back sides, and supplies the electrolyte to each electrode and discharges the electrolyte from each electrode. Do.

  The redox flow battery of the present invention includes the cell stack for the redox flow battery of the present invention, each electrode tank storing each electrode electrolyte supplied to each electrode provided in the cell stack, the cell stack, and each electrode. And a flow passage for transferring each of the electrode electrolytes to and from the tank.

  According to the present invention, since the lateral groove exists so as to prevent the flow of the electrolytic solution, it is possible to effectively reduce or substantially eliminate the electrolytic solution that passes without contributing to the battery reaction. Therefore, according to the present invention, the battery reaction can be sufficiently performed by the electrode, the internal resistance is hardly increased due to the passage of the electrolytic solution, and the internal resistance can be reduced as shown in a test example described later. In addition, the electrolytic solution easily flows in the lateral groove portion as compared with other portions of the electrode. For this reason, the electrolyte can be distributed well, and the pressure of the electrolyte flowing in the lateral groove tends to be uniform along the longitudinal direction of the lateral groove. Therefore, even when there is a defect in a part of the longitudinal direction of the lateral groove, the electrolytic solution sufficiently flows in a portion other than the defect, so that the electrolytic solution can be sufficiently distributed to the downstream region of the lateral groove. . That is, according to the present invention, it is difficult for the electrolytic solution to stay in the electrode, and variations in the flow rate of the electrolytic solution due to the stay are unlikely to occur. According to the present invention, a state in which the active material is locally insufficient in the electrode is unlikely to occur, and overcharge due to the lack of active material and side reactions associated with this overcharge are unlikely to occur. Furthermore, since the electrolyte solution can sufficiently flow through the lateral groove, the depth of charge of the electrolyte solution in the electrode is made uniform, so that the depth of charge of the electrolyte solution can be prevented from locally increasing in the electrode. Also from this fact, the present invention is less likely to cause side reactions associated with overcharge and overcharge.

  Therefore, according to the present invention, (1) the electrolyte solution can flow uniformly in the electrode, (2) the overcharge can be prevented, and the charge depth of the electrolyte solution can be made uniform. 3) It has an excellent effect of suppressing the oxidative deterioration of the RF battery components such as electrodes due to the overcharge side reaction and extending the life of the RF battery components. In addition, the frequency of maintenance can be reduced by suppressing the deterioration, and the RF battery of the present invention is easy to manage and has high reliability.

  In the present invention, the electrode has a lateral groove portion and a region other than the lateral groove portion, and the lateral groove portion functions as a flow promoting portion of the electrolyte, and the region other than the lateral groove portion is typically in the longitudinal direction of the lateral groove in the electrode. Along with this, it functions as a rectification point that promotes the electrolyte to spread throughout the electrode.

  In the present invention, the electrode typically has a rectangular shape. In addition, a polygonal shape, a circular shape, an elliptical shape, a racetrack shape, and the like may be used. However, considering the electrode occupancy ratio in the entire RF battery and the space when the RF battery is installed, the rectangular shape is considered easy to use. It is done.

  In the present invention, the flow direction of the electrolyte is a direction connecting two opposite sides (peripheries) in the rectangular or polygonal electrodes. Typically, the up-down direction or the left-right direction can be mentioned. In the case of a circular or elliptical electrode, the radial direction may be mentioned.

  As one form of this invention, the form whose inclination | tilt angle with respect to the said flow direction in the said horizontal groove is 90 degrees +/- 10 degrees is mentioned.

  When the tilt angle approaches 0 ° or 180 °, the electrolyte solution may pass without contributing to the battery reaction as in the case of the conventional fluted electrode. Therefore, the inclination angle is preferably 90 ° ± 10 °. As the inclination angle is closer to 90 ° (for example, within 90 ° ± 5 °), 90 ° is considered to be most preferable because the effect of reducing the electrolyte solution that passes without contributing to the battery reaction is high.

  As one form of this invention, the form which provided the said horizontal groove in multiple numbers and these horizontal grooves were provided in parallel is mentioned.

  The number of the transverse grooves may be one, but in the case of a plurality of electrodes, as described above, the electrolyte circulation promotion locations (lateral groove portions) and the rectification locations (regions other than the lateral groove portions) are alternately arranged. It is possible to repeatedly promote and rectify the flow of the electrolyte. As a result, the electrolytic solution can flow more uniformly in the electrode.

  As one aspect of the present invention, at least one of the flow grooves is a vertical groove whose longitudinal direction is substantially parallel to the flow direction of the electrolyte solution, and the electrode is the horizontal groove. And the form which has several area | region divided by the said vertical groove is mentioned.

  The electrode can be configured to have only a lateral groove. However, in addition to the various effects of the lateral groove described above, the vertical groove can be formed by providing the longitudinal groove in addition to the lateral groove as in the above embodiment. Effect: Can also have a reduction in pressure loss. Moreover, since the RF battery of the said form has few pressure losses, the motive power of the pump utilized for supply of each electrolyte solution can be made small, and system efficiency is high.

  As one form of this invention, the said horizontal groove and the said vertical groove are provided with two or more, and the form which these horizontal grooves and the vertical grooves cross | intersected in the grid | lattice form is mentioned.

  According to the above aspect, in addition to the effect of providing a plurality of lateral grooves as described above, that is, in addition to the uniform flow of the electrolytic solution by repeating the circulation and rectification of the electrolytic solution, the longitudinal grooves can reduce the pressure loss. Can be planned. In addition, there are a plurality of intersections with the lateral grooves per longitudinal groove, and at each intersection, at least a part of the electrolyte flowing through the longitudinal groove portion flows along the longitudinal direction of the lateral grooves. Therefore, according to the said form, compared with the conventional electrode with a longitudinal groove, the electrolyte solution which passes without contributing to a battery reaction can be reduced effectively, and it is anticipated that a battery reaction can be performed by the whole electrode.

  In the redox flow battery of the present invention, the electrolyte easily flows evenly in the electrode. The redox flow battery cell of the present invention and the cell stack for redox flow battery can be suitably used for the constituent member of the redox flow battery of the present invention.

FIG. 1 (A) is a schematic plan view showing a state in which an electrode included in the RF battery of Embodiment 1 is arranged on a frame, FIG. 1 (B) is a BB cross-sectional view of this electrode, and FIG. FIG. 3 is an exploded perspective view for explaining an arrangement state of the electrodes and the frame. FIG. 2 shows the relationship between the flow rate of the electrolyte solution per unit area of the electrode and the internal resistance per unit time in an RF battery including an electrode provided with a lateral groove and an RF battery including an electrode provided with a vertical groove. It is a graph which shows a relationship. FIG. 3 (A) is a schematic plan view showing a state in which the electrodes included in the RF battery of Embodiment 2 are arranged on the frame, and FIG. 3 (B) is a cross-sectional view of this electrode taken along the line BB. FIG. 4 (A) is a schematic plan view showing a state where the electrodes included in the RF battery of Embodiment 3 are arranged on the frame, FIG. 4 (B) is a BB cross-sectional view of this electrode, and FIG. 4 (C) is FIG. 4 is a CC cross-sectional view of this electrode. FIG. 5 is an explanatory diagram showing the operation principle of the RF battery. FIG. 6 is a schematic configuration diagram of a cell stack included in a conventional RF battery.

  Hereinafter, a redox flow battery (RF battery), an RF battery cell included in the battery, and a cell stack for an RF battery will be described with reference to the drawings. In the figure, the same reference numeral indicates the same name object.

  The basic configuration of the RF battery of the present invention is the same as that of the conventional RF battery shown in FIGS. That is, a positive electrode 14 through which a positive electrolyte solution is circulated, a negative electrode 15 through which a negative electrode electrolyte solution is circulated, and a diaphragm (typically an ion exchange membrane) 101 interposed between both electrodes 14 and 15 A battery cell 10 is provided. More specifically, this RF battery has a cell stack (FIG. 6) in which the battery cell 10 and the frame 12 having the bipolar plate 121 on which the electrode electrodes 14 and 15 are arranged on the front and back are alternately stacked. In addition, each electrode tank (FIG. 5) for storing each electrode electrolyte supplied to each electrode 14, 15 and a pipe (FIG. 5) connected to the cell stack and each electrode tank and serving as a flow path for the electrolyte solution 5) with. In this RF battery, an electrolytic solution such as a sulfuric acid solution containing metal ions such as vanadium ions as an active material is supplied from the electrode tanks to the cell stack to perform a battery reaction. This RF battery typically has an AC / DC converter through a power generation unit (e.g., a general power plant (thermal power, hydropower, nuclear power, wind power, solar power, etc.), a general house or a collective. Connected to solar power generators (including distributed power supplies such as wind power generators installed in various places including houses) and loads (customers such as ordinary households, plants, factories, etc.) and using the power generation unit as a power supply source Charging is performed and discharging is performed with the load as a power supply target. The RF battery of the present invention is assembled between the power generation unit and the load as described above and used as one element of the power system.

  The RF battery of the present invention is characterized by the shape of the electrode 1A that is a constituent member of the battery cell 10. Hereinafter, the description will be focused on the electrode 1A, and detailed description of other components will be omitted.

[Embodiment 1]
(Constitution)
An electrode 1A included in the RF battery cell of Embodiment 1 will be described with reference to FIG.

  The electrode 1A used for the positive electrode 14 and the negative electrode 15 is a rectangular plate material, and includes a plurality of electrolytic solution flow grooves 2A on one surface (for example, the surface in contact with the diaphragm 101). Each of the flow grooves 2A is a straight line extending in the left-right direction from one periphery to the other periphery so as to connect two opposing sides of the electrode 1A (here, the periphery extending in the up-down direction disposed on the left and right). Are formed in parallel with each other at regular intervals. Note that the number of flow grooves in FIG. 1 and FIGS. 3 and 4 to be described later is merely an example.

  Each flow groove 2A is a horizontal groove provided such that its longitudinal direction is perpendicular to the flow direction of the electrolyte. Here, the flow direction of the electrolytic solution is a direction (here, the vertical direction) connecting the two opposite sides (here, the peripheral edge extending in the left-right direction) of the electrode 1A. Accordingly, each flow groove 2A is provided in parallel with another opposing two sides (here, a peripheral edge arranged vertically and extending in the left-right direction) in electrode 1A. By providing a plurality of such lateral grooves, the surface of the electrode 1A has a shape in which the lateral grooves and rectangular regions (hereinafter referred to as rectifying regions) 3A in which the lateral grooves are not formed are alternately arranged.

  The electrode 1A is used by being disposed on a rectangular bipolar plate 121 surrounded by a rectangular frame 12. The frame 12 has a liquid supply hole (a liquid supply hole 123 for the positive electrode 14 and a liquid supply hole 124 for the negative electrode 15) and a liquid discharge hole (a liquid discharge hole 125 for the positive electrode 14 and a liquid discharge hole 125 for the negative electrode 15). A liquid hole 126) is provided. Further, on one surface of the frame 12 (the front surface in FIG. 1A), a liquid introduction groove 123i continuous with the positive electrode supply hole 123 and a liquid discharge groove 125o continuous with the positive electrode drain hole 125 are provided. A liquid introduction groove 124 i continuous with the negative electrode liquid supply hole 124 and a liquid discharge groove 126 o continuous with the negative electrode liquid discharge hole 126 are provided on the back surface (in FIG. 1A). The electrode 1A disposed on the bipolar plate 121 is supplied with each electrolyte from the liquid supply holes 123 and 124 through the liquid introduction grooves 123i and 124i. The supplied electrolyte is used for the battery reaction, and then discharged from the drain holes 125 and 126 through the liquid discharge grooves 125o and 126o from the electrode 1A.

  In a state where the electrode 1A is disposed on the bipolar plate 121, the flow direction of the electrode can be defined by the formation positions of the liquid supply holes 123 and 124 and the drainage holes 125 and 126. For example, when the liquid supply holes 123 and 124 and the drainage holes 125 and 126 are formed in different regions (here, upper and lower regions) of the frame 12 as shown in FIG. Direction). For example, when the liquid supply holes 123 and 124 and the drain holes 125 and 126 are formed in the same region of the frame 12 (only the upper region, etc.), the openings of the liquid introduction grooves 123i and 124i that are continuous with the liquid supply holes 123 and 124 are positioned. And the region where the openings of the liquid discharge grooves 125o and 126o continuous to the drain holes 125 and 126 are located.

  Here, although the liquid supply holes 123 and 124 and the drainage holes 125 and 126 are respectively provided in respective regions (upper and lower regions in FIG. 1A) in the frame 12, the liquid supply holes 123 and 124 and the drainage are shown. There is also a form in which the holes 125 and 126 are provided in the region on the same side of the frame (in FIG. 1A, only the upper region, only the lower region, only the left region, or only the right region). In addition, here, a mode in which each of the liquid supply holes 123 and 124 and the liquid discharge holes 125 and 126 is provided is shown, but there is also a mode in which a plurality of liquid supply holes 123 and 124 and a plurality of liquid discharge holes 125 and 126 are provided.

  The cross-sectional shape and the longitudinal shape of the flow groove (lateral groove) 2A can be selected as appropriate. For example, examples of the cross-sectional shape include a rectangular shape, a semicircular shape, and a V shape. The shape in the longitudinal direction can be a wave shape, a zigzag shape, or the like, in addition to the linear shape. In the case of a shape other than a straight line such as a wave shape, the longitudinal direction of the circulation groove is a direction along a straight line passing through the center of the waveform or the zigzag amplitude. The groove width, depth, number of circulation grooves (lateral grooves) 2A, and intervals for forming each groove can be selected as appropriate. Moreover, when providing a some distribution | circulation groove | channel, it can be set as the form which varied the cross-sectional shape, groove width, and depth of each groove | channel. Further, the flow grooves (lateral grooves) 2A can be provided on both surfaces of the electrode 1A. When the flow grooves are provided on both surfaces, the specifications such as the cross-sectional shape of the flow grooves (lateral grooves) 2A on each surface, the arrangement position, the number, etc. may be different. The contents relating to the cross-sectional shape, the shape in the longitudinal direction, the groove width, the depth, the number, and the formation position are the same for the flow groove (vertical groove) 2C of the third embodiment to be described later.

  As the electrode 1A, a known material, typically, a carbon felt made of carbon fiber can be used. Then, the flow groove 2A may be formed in a desired material by an appropriate method such as press working, cutting, or line embossing.

(Electrolyte flow)
When the RF battery including the electrode 1A is operated, the electrolytic solution is supplied from the liquid supply hole 123 (124) to the electrode 1A through the liquid introduction groove 123i (124i). The electrolytic solution that has passed through the opening of the liquid introduction groove 123i (124i) spreads from the periphery of the electrode 1A (the lower edge in FIG. 1A) to the entire rectification region 3A along the periphery. That is, the region 3A functions as a rectifying unit. The electrolyte solution in the rectifying region 3A advances from below to above as indicated by an arrow here. When the electrolytic solution having passed through the rectifying region 3A reaches the flow groove 2A, the flow direction of the flow groove 2A (the left-right direction in FIG. ) The electrolyte flows along. That is, the flow groove 2A functions as a flow promoting part for the electrolytic solution. The electrolyte solution that has passed through the flow groove 2A spreads over the entire region 3A as described above in the rectification region 3A on the downstream side of the flow groove 2A. The electrolytic solution is directed upward while repeating this rectification and promotion of circulation, and is finally collected in the liquid discharge groove 125o (126o) and discharged from the drain hole 125 (126).

(effect)
According to the RF battery, since the flow of the electrolytic solution is once blocked by the flow groove (lateral groove) 2A, it is possible to effectively reduce the electrolytic solution that passes through the electrode 1A without contributing to the battery reaction. Can do. In addition, since the electrolytic solution flows more easily in the flow groove (lateral groove) 2A portion than in the rectifying region 3A, this RF battery can ensure a good flow of the electrolytic solution as a whole. Furthermore, even if there is a defect in a part of the flow groove (lateral groove) 2A, the electrolyte solution can flow well in the flow groove (lateral groove) 2A other than the defect, and the electrolyte solution By reaching the rectifying region 3A on the downstream side of the flow groove (lateral groove) 2A and spreading over the entire region 3A, the electrolyte can be distributed to the downstream region of the defect. Therefore, the RF battery can sufficiently perform a battery reaction and suppress an increase in internal resistance.

  Further, in the RF battery, it is difficult for the electrolytic solution to stay in the electrode, and the flow rate of the electrolytic solution can be suppressed from being locally different. As a result, overcharge can be suppressed. Furthermore, in the RF battery, the charging depth of the electrolytic solution is made uniform when passing through the flow groove (lateral groove) 2A, so that the charging depth of the electrolytic solution can be prevented from being locally different. Also from this, the RF battery can suppress overcharge. In addition, in the RF battery, it is expected that the electrode 12A itself has a rectifying function, so that it is not necessary to provide a rectifying groove in the frame 12, or the shape of the rectifying groove can be simplified.

  Furthermore, the RF battery can flow the electrolyte uniformly in the electrode, and further suppress the oxidative deterioration of the constituent parts of the RF battery due to the side reaction of the overcharge, so that the long life of the constituent parts is achieved. Can be achieved. In particular, it is considered that the above-described various effects can be sufficiently obtained by providing the plurality of flow grooves (lateral grooves) 2A in the RF battery.

[Test example]
An RF battery including an electrode provided with a flow groove perpendicular to the flow direction of the electrolyte (hereinafter referred to as a lateral groove electrode) and a vertical groove electrode provided with a flow groove parallel to the flow direction of the electrolyte A prepared RF battery was fabricated, and the internal resistance in the battery was measured. The result is shown in FIG.

The electrodes with horizontal grooves and vertical grooves used in this test have the same configuration (electrode material, groove cross-sectional shape, groove width, depth, number) except that the formation direction of the flow grooves is different. The area of each electrode was 500 cm ² . A cell stack as shown in FIG. 6 was prepared using the above electrode, and the amount of electrolyte solution (here, vanadium sulfate solution used) supplied per unit time (min) was changed. Here, the amount of electrolytic solution per unit area of the electrode (milliliter (ml = cc) / cm ² ) is 0.4 ml / cm ² , 0.6 ml / cm ² , 0.8 ml / cm ^2. Changed. Then, the internal resistance per cell (cell resistivity: Ω · cm ² / cell) in each electrolyte amount was determined as follows. Each cell stack produced was subjected to constant current charge / discharge at a current density of 70 mA / cm ² , the terminal voltage at the time of charge / discharge was measured, and the cell resistivity was determined from the transition of the measured value of the terminal voltage. The results are shown in Table 1 and FIG.

  As shown in Table 1 and FIG. 2, the larger the amount of electrolyte solution per unit area of the electrode per unit time, the smaller the internal resistance. In particular, it can be seen that an RF battery having a lateral grooved electrode has a lower electrical resistance than an RF battery having a vertical grooved electrode. The reason for this result is considered to be that the electrode with lateral grooves flows better than the electrode with vertical grooves as described above.

[Embodiment 2]
In the first embodiment, the configuration in which the flow groove 2A provided in the electrode 1A is orthogonal to the flow direction of the electrolytic solution has been described. In addition, like the electrode 1B shown in FIG. 3, a configuration in which the flow grooves 2B are provided so as to intersect non-orthogonally with respect to the flow direction of the electrolytic solution can be mentioned. Here, the description will focus on the electrode 1B, and detailed description of other overlapping configurations and effects will be omitted.

  The electrode 1B also includes a plurality of linear flow grooves 2B arranged in parallel at equal intervals from one peripheral edge to the other peripheral edge. In particular, each of the flow grooves 2B is a groove provided such that its longitudinal direction intersects non-orthogonally with the flow direction of the electrolyte solution (the vertical direction here). That is, each circulation groove 2B is provided so as to intersect two opposite sides (here, a peripheral edge arranged vertically and extending in the left-right direction) in the electrode 1B. Here, the inclination angle θ with respect to the distribution direction (indicated by a two-dot chain line in FIG. 3A) in each distribution groove 2B is set to 81 °. Such a flow groove 2B that satisfies the inclination angle θ of 90 ° ± 10 ° is also referred to as a transverse groove. In particular, here, the liquid supply hole 123 (124) and the drainage hole 125 (126) are provided at substantially diagonal positions, and the flow groove 2B is formed from each electrode liquid supply hole to each electrode drainage hole. It is inclined in the same direction almost diagonally. On the front side of the paper shown in FIG. 3 (A): on the positive electrode side, the flow groove 2B is inclined upward from the liquid supply hole 123 toward the drain hole 125, and on the back side of the paper: the negative electrode is not shown in the figure. The flow groove 2B is inclined upward from the liquid supply hole 124 toward the liquid discharge hole 126. Therefore, when seen through in a state where the bipolar electrodes are stacked, the flow grooves 2B of the polar electrodes are crossed. The rectifying region 3B formed between the flow grooves 2B has a trapezoidal shape or a parallelogram shape.

  The inclination angle θ of the flow groove 2B can be appropriately selected within a range of 90 ° ± 10 °. Further, the direction of inclination of the flow groove 2B can also be selected as appropriate. In addition, a groove that intersects non-orthogonally with respect to the flow direction, such as the flow groove 2B, and a groove that is orthogonal to the flow groove 2A described in the first embodiment can be combined.

  Similarly to the first embodiment, the RF battery including the electrode 1B can effectively reduce the electrolyte passing through the electrode 1B without contributing to the battery reaction by the flow groove (lateral groove) 2B.

[Embodiment 3]
In the first and second embodiments, the mode in which the inclination angle of the flow grooves 2A and 2B provided in the electrodes 1A and 1B with respect to the flow direction of the electrolyte is 90 ° ± 10 ° has been described. In addition, as in the electrode 1C shown in FIG. 4, a configuration including both a flow groove (lateral groove) 2A perpendicular to the flow direction of the electrolyte and a flow groove (vertical groove) 2C parallel to the flow direction of the electrolyte Is mentioned. Here, the description will be focused on the electrode 1C, and detailed description of other overlapping configurations and effects will be omitted.

  The electrode 1C is similar to the electrode 1A described in the first embodiment, on one surface thereof, from one periphery of two opposing sides (here, a periphery extending in the vertical direction in the left and right directions) toward the other periphery, A plurality of linear flow grooves (lateral grooves) 2A extending in the left-right direction are provided in parallel at equal intervals. In addition, in the electrode 1C, a plurality of linear flow grooves 2C extending in the vertical direction from one peripheral edge of another two opposite sides (peripheral edges arranged in the vertical direction and extending in the left-right direction here) toward the other peripheral edge. At equal intervals. These flow grooves 2C are vertical grooves provided in parallel to the flow direction of the electrolytic solution. That is, the electrode 1C is provided with a plurality of flow grooves 2A, 2C in parallel with the peripheral edges of the electrode 1C, and the flow grooves 2A, 2C are provided so as to be orthogonal to each other, so that the surface of the electrode 1C has a checkered pattern. It has become. A rectangular region surrounded by both grooves 2A and 2C is a rectifying region 3C.

  Here, the form in which the flow grooves (lateral grooves) 2A and the flow grooves (longitudinal grooves) 2C are orthogonal to each other has been described, but both the grooves 2A and 2C are grooves having an appropriate inclination angle, and the electrode surface has a diamond pattern. You may do it. Further, the number of the flow grooves (lateral grooves) 2A and the flow grooves (vertical grooves) 2C can be appropriately selected as long as the area of the rectifying unit 3C is not excessively small. Further, the cross-sectional shape, groove width, groove depth, and the like can be made different between the flow groove (lateral groove) 2A and the flow groove (vertical groove) 2C.

  When an RF battery including the electrode 1C is operated, a part of the electrolyte supplied to the electrode 1C from the liquid supply hole 123 (124) through the liquid introduction groove 123i (124i) is as described in the first embodiment. And the entire rectification region 3C along the periphery (the lower edge in FIG. 4 (A)), and in the same way as in the first embodiment, the flow of the electrolyte by the flow groove (lateral groove) 2A and the rectification by the rectification region 3C To the downstream drainage hole 125 (126).

  On the other hand, the other part of the electrolyte supplied from the liquid supply hole 123 (124) to the electrode 1C through the liquid introduction groove 123i (124i) flows through the flow groove (vertical groove) 2C. However, the electrolyte flowing through the flow grooves (vertical grooves) 2C, unlike the conventional electrodes with vertical grooves, when reaching the intersection with the flow grooves (lateral grooves) 2A, the longitudinal direction of the flow grooves (lateral grooves) 2A (FIG. 4 ( In A), the electrolytic solution that flows along the horizontal direction) and flows into the flow groove (lateral groove) 2A is introduced into the rectification region 3C on the downstream side of the flow groove (lateral groove) 2A. Thus, in the electrode 1C, the electrolyte flowing through the flow groove (vertical groove) 2C is directed toward the drain hole 125 (126) while the flow is relaxed at each intersection with the flow groove (lateral groove) 2A.

  Although the RF battery including the electrode 1C includes a flow groove (vertical groove) 2C, the flow groove (lateral groove) 2B, as in the first embodiment, allows the electrolysis to pass through the electrode 1C without contributing to the battery reaction. The liquid can be effectively reduced. In particular, in the electrode 1C, the flow groove (vertical groove) 2C is expected to facilitate the flow of the electrolyte compared to the first embodiment, and to easily reduce the pressure loss of the electrolyte and the variation in the pressure state of the electrode. Is done. From this, the RF battery including the electrode 1C is expected to make the flow of the electrolyte more uniform over the entire electrode. In addition, since the pressure loss can be reduced, the RF battery is expected to have the effect of reducing the allowable pressure of the cell when flowing the electrolyte and reducing the pump power.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the number / inclination angle of the circulation grooves, the groove formation interval, the formation surface of the circulation grooves, and the like can be appropriately changed.

  The RF battery of the present invention is used for new energy generation such as solar power generation and wind power generation for the purpose of stabilizing fluctuations in power generation output, storing electricity when surplus generated power, leveling load, etc. It can be suitably used for purposes such as power supply leveling and power level reduction. The cell stack for an RF battery of the present invention and the RF battery cell of the present invention can be suitably used as a constituent member of the RF battery of the present invention.

1A, 1B, 1C Electrode 2A, 2B Flow groove (horizontal groove) 2C Flow groove (vertical groove)
3A, 3B, 3C rectification region
10 Battery cells 12 Frame 14 Positive electrode 15 Negative electrode
100 Redox flow battery 101 Diaphragm 102 Positive electrode cell 103 Negative electrode cell
104 Positive electrode 104s Distribution groove 105 Negative electrode 106 Positive tank
107 Negative electrode tank 108,109,110,111 Piping 112,113 Pump
121 Bipolar plate 122 Frame 123 Positive electrode supply hole 123i, 124i Liquid introduction groove
124 Negative electrode feed hole 125 Positive electrode drain hole 125o, 126o Liquid drain groove 126 Negative electrode drain hole
127 Seal member
200 Cell stack 210 End plate 220 Tightening member

Claims (7)

A redox flow battery cell comprising a positive electrode through which a positive electrode electrolyte is circulated, a negative electrode through which a negative electrode electrolyte is circulated, and a diaphragm interposed between the two electrodes,
The electrode has at least one electrolyte flow channel on its surface;
At least one of the flow grooves is a lateral groove provided so that the longitudinal direction thereof is substantially orthogonal to the flow direction of the electrolyte solution.   2. The redox flow battery cell according to claim 1, wherein the lateral groove has an inclination angle of 90 ° ± 10 ° with respect to the flow direction.   3. The redox flow battery cell according to claim 1, wherein a plurality of the lateral grooves are provided, and the lateral grooves are provided in parallel. At least one of the flow grooves is a vertical groove provided such that its longitudinal direction is substantially parallel to the flow direction of the electrolyte solution,
4. The redox flow battery cell according to claim 1, wherein the electrode has a plurality of regions partitioned by the horizontal groove and the vertical groove.   5. The redox flow battery cell according to claim 4, wherein a plurality of the horizontal grooves and the vertical grooves are provided, and the horizontal grooves and the vertical grooves intersect in a lattice pattern. Redox flow battery cell according to any one of claims 1 to 5,
A plurality of frames are provided on the outer periphery of the bipolar plate disposed on the front and back of each electrode, and a plurality of frames for alternately supplying the electrolyte to each electrode and discharging the electrolyte from each electrode. A cell stack for a redox flow battery.   7. The cell stack for the redox flow battery according to claim 6, each electrode tank storing each electrode electrolyte supplied to each electrode provided in the cell stack, and between the cell stack and each electrode tank A redox flow battery comprising a flow path for transferring each of the electrode electrolytes.

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