Cell frame, cell stack, and redox flow battery

Abstract

To reduce the pressure loss of an electrolyte being circulated and to reduce the shunt current loss.SOLUTION: A cell frame 1 is formed in a frame 5, communicates with manifolds 11, 12, 21, 22 and an electrode arrangement portion 105, widens channels 31, 32, 41, 42 through which an electrolytic solution flows from the manifold 11, 12, 21, 22 side toward the inner circumference width of the frame 5 around the electrode arrangement portion 105, and backflow prevention parts 60, 70 are provided in the middle to prevent backflow of the electrolytic solution.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a self-frame for circulating an electrolytic solution, a cell stack using the same, and a redox flow battery. In particular, the present invention relates to a self-frame, a cell stack, and a redox flow battery that can reduce the pressure loss of the circulating electrolytic solution and reduce the shunt current loss.

Background Art

[0002] In recent years, due to the suppression of global warming and the protection of the global environment, the interest in power generation technologies using renewable natural energy such as solar power generation and wind power generation has rapidly increased and their introduction has been promoted. In such power generation methods, output fluctuations occur, so power storage technology (energy storage technology) has attracted attention as a technology for absorbing the output fluctuations and stabilizing the power grid. And, as one of the energy storage devices, a redox flow battery is known. A redox flow battery is a storage battery that circulates an electrolytic solution in which an active material is dissolved in a solvent by a pump and performs charge and discharge by the oxidation-reduction reaction of ions in the electrolytic solution. The electrodes and the electrolytic solution have a long life and high safety, but cost reduction is desired for its widespread use, and increasing the output is important for cost reduction.

[0003] In this redox flow battery, in order to obtain a predetermined voltage, it generally has a configuration of a cell stack in which a plurality of battery cells (single cells) are stacked. Generally, a positive and a negative electrode are arranged between adjacent self-frames via a separator to form one battery cell (single cell), and a plurality of such single cells are stacked to form a cell stack. On the positive electrode side of the battery cell of the cell stack, a positive electrolytic solution is supplied from a positive electrolytic solution tank that stores the positive electrolytic solution, and on the negative electrode side, a negative electrolytic solution is supplied from a negative electrolytic solution tank that stores the negative electrolytic solution. Charge and discharge are performed by simultaneously advancing the oxidation reaction and the reduction reaction on the positive and negative electrodes. At this time, the positive and negative electrolytic solutions are circulated between the electrolytic solution tank and the battery cell using a circulation pump. Thus, redox flow batteries are configured to supply electrolyte to the battery cells using a circulation pump. To achieve high output, it is desirable to have a low internal resistance in the battery and to minimize pressure loss when supplying electrolyte to the electrodes.

[0004] In this case, the supply of electrolyte to the electrodes in the cell stack is carried out by forming a channel through which the electrolyte flows in the cell frame on which the electrodes are arranged. For example, as disclosed in Patent Document 1 and Patent Document 2, a manifold formed through the cell frame and slits formed on the surface of the cell frame constitute the electrolyte flow path in the cell frame. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. WO2019 / 234867 [Patent Document 2] Japanese Patent Publication No. 2020-129501 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the flow path structure of the cell frame disclosed in Patent Documents 1 and 2, the electrolyte is circulated through a substantially L-shaped slit with a flow path width smaller than that of the manifold. By making the slit that serves as the electrolyte flow path small in diameter and increasing the length of the slit, as in Patent Documents 1 and 2, the electrical resistance of the electrolyte within the slit can be increased, thereby reducing the loss of shunt current. However, making the slit small in diameter and increasing the length of the slit increases the pressure loss, which increases the loss of the circulation pump and reduces the battery efficiency and energy efficiency.

[0007] Therefore, the present invention aims to provide a cell frame, cell stack, and redox flow battery that can achieve both a reduction in pressure loss of the circulating electrolyte and a reduction in shunt current loss. [Means for solving the problem]

[0008] The cell frame of the invention according to claim 1 has a frame body provided around an electrode arrangement section where electrodes are arranged, a manifold that penetrates through the front and back, and a flow path that connects the manifold and the electrode arrangement section and through which the electrolyte flows, the flow path is formed to widen from the manifold side toward the width of the inner circumference of the frame body around the electrode arrangement section, and a backflow prevention section is provided in the middle to prevent backflow of the electrolyte.

[0009] Here, the electrode arrangement section may have a structure that accommodates positive and negative electrodes via a bipolar plate, or it may have a structure in which the electrodes are provided integrally with the frame. Furthermore, the frame is provided around the electrode arrangement section, and is usually roughly rectangular in shape, and is made of, for example, polyvinyl chloride. The manifold of the above-described frame is a through-hole formed through the thickness (front and back) of a cell frame that is formed in a roughly rectangular shape with four sides having two opposing sides of the same length. There are four through-holes: a through-hole for supplying positive electrode electrolyte to the positive electrode, a through-hole for discharging positive electrode electrolyte that has passed through the positive electrode to the outside, a through-hole for supplying negative electrode electrolyte to the negative electrode, and a through-hole for discharging negative electrode electrolyte that has passed through the negative electrode to the outside. For example, it is provided at the corners of the frame, that is, at the four corners formed by the intersection of two adjacent sides, with one set of two opposing corners and the other set of two opposing corners. One of the positive or negative electrolytes flows through the manifold provided at one set of two opposing corners, and the other of the positive or negative electrolytes flows through the manifold provided at the other set of two opposing corners. Its shape is not particularly limited, but it is usually formed in a circular shape such as a perfect circle.

[0010] The above-mentioned flow path is a groove-shaped recess through which the electrolyte flows, connecting the manifold and the electrode arrangement section. It is formed on the positive electrode side through which the positive electrode electrolyte flows and on the negative electrode side through which the negative electrode electrolyte flows, and is formed on the top and bottom of the frame via the electrode arrangement section. Furthermore, this flow path is formed to widen from the manifold side of the frame towards the width of the inner circumference where the electrode arrangement section is provided. The description of the above-mentioned flow path as widening from the manifold side towards the width of the inner circumference where the electrode arrangement section is provided means that the flow path is gradually widened to a width that matches the width of the inner circumference of the frame surrounding the electrode arrangement section. This means that on the supply side to the electrodes, the electrolyte from the manifold is diffused and supplied to the electrodes of the electrode arrangement section, and on the discharge side of the electrolyte that has passed through the electrodes on the opposite side, the electrolyte that has passed through the electrodes is concentrated and guided to the manifold. As long as the flow path is expanded towards the width of the inner circumference of the frame to a width that matches both widths, it is not required that it be continuously widened between the communication point between the manifold and the electrode arrangement section, and there may be a section on the manifold side where the width is constant. Here, the width of the inner circumference of the frame refers to the distance between a pair of opposing inner edges of the inner circumference of the frame, or in other words, the width of the electrode arrangement section provided on the inner circumference of the frame. Note that this width refers to the width in the left-right direction, which is perpendicular to the vertical direction when the electrolyte flows from bottom to top through the cell frame.

[0011] Furthermore, the above-mentioned backflow prevention section only needs to be provided in the middle of the flow path to prevent backflow of the electrolyte. For example, a valve membrane or check valve may be provided in the groove of the flow path, or steps, grooves, slopes, etc., may be provided in the flow path, or a standing piece may be formed by cutting and bending from the surface of the frame, with the free end side opposite the base end on the side connected to the frame being open, and a dead end formed below the standing piece.

[0012] Claim 1 The flow path of the cell frame of the invention is composed of a straight flow path that extends from the manifold parallel to the width direction of the inner circumference of the frame and is narrower than the diameter of the manifold, and a wide flow path that widens from the straight flow path toward the width of the inner circumference of the frame.

[0013] The flow path of the cell frame according to claim 2 has a groove bottom that rises from the lower side of the frame parallel to the width direction of the inner circumference of the frame towards the electrode arrangement portion, and the cross-sectional area of ​​the flow path that circulates the electrolyte from bottom to top on the electrolyte supply side between adjacent diaphragms is narrowed from the bottom towards the inner circumferential edge of the boundary with the electrode arrangement portion. The phrase "rising groove bottom of the flow path" means that the groove bottom of the flow path on the electrolyte supply side is sloped so that it gradually becomes shallower. The vertical direction of the frame's sides corresponds to the vertical direction in which the electrolyte flows from bottom to top.

[0014] The flow path of the cell frame according to claim 3 has ribs formed on the side connected to the manifold. The above-mentioned ribs are located near the manifold and have the function of reinforcing the cell frame 1, preventing adjacent diaphragms from entering the flow path due to the internal pressure of the electrolyte flowing through the manifold, and holding down the diaphragms. Their shape and form are not particularly limited, and for example, they may be formed as straight protrusions, and there may be one or multiple ribs.

[0015] The backflow prevention portion of the cell frame according to claim 4 is formed by cutting and bending a piece from the surface of the frame, so that the free end side of the piece opposite to the base end on the side connected to the frame is open, forming a dead end below the piece. The above-mentioned backflow prevention section is formed by cutting and bending the surface of the frame, with one end connected to the frame serving as the base end and the other end serving as the free end, and consists of an upright piece and a dead end formed below the upright piece. For example, by bending the base end and plastically deforming it so that it slopes upward from the base end to the free end, an upright piece that slopes from the base end is formed, and the free end opens up to form a dead end below the upright piece. As a result, in the supply-side flow path that supplies electrolyte to the electrodes, the base end on one end of the upright piece corresponds to the upstream side, and the free end on the other end corresponds to the downstream side. In the electrolyte flow direction, where electrolyte is supplied from the manifold side to the electrode side, the base end on one end of the upright piece is connected to the frame, so the electrolyte flows over the upper surface of the upright piece. On the other hand, electrolyte attempting to flow back from the electrode placement side is prevented from flowing back because the free end of the upright piece is open, causing the electrolyte to flow into the opening and be blocked there. In the discharge flow path for discharging electrolyte, the base end of one end of the upright piece corresponds to the upstream side, and the free end of the other end corresponds to the downstream side. In the direction of electrolyte flow, where electrolyte is discharged from the electrode side toward the manifold side, the base end of one end of the upright piece is connected to the frame, causing the electrolyte to flow over the upper surface of the upright piece. On the other hand, electrolyte attempting to flow back from the manifold side is prevented from flowing back because the free end of the upright piece is open, causing the electrolyte to flow into the opening and be blocked there.

[0016] Claim 5 The cell stack of the invention comprises a plurality of stacked battery cells, each cell frame consisting of positive and negative electrodes, a diaphragm placed between the positive and negative electrodes, an electrode arrangement section where the positive and negative electrodes are arranged, and a frame provided around the electrode arrangement section. The cell frame has a manifold that penetrates the front and back of the frame provided around the electrode arrangement section, and a flow path that connects the manifold and the electrode arrangement section and through which the electrolyte flows. The flow path is formed to widen from the manifold side toward the width of the inner circumference of the frame around the electrode arrangement section, and a backflow prevention section is provided along the way to prevent backflow of the electrolyte.

[0017] Claim 6 The redox flow battery of the invention according to claim 1 comprises a cell stack formed by laminating a plurality of battery cells each composed of a positive and a negative electrode, a separator disposed between the positive and negative electrodes, a self-frame including an electrode arrangement part where the positive and negative electrodes are arranged and a frame provided around the electrode arrangement part. The frame provided around the electrode arrangement part has a manifold penetrating the front and back, and a flow path communicating between the manifold and the electrode arrangement part through which an electrolytic solution flows. The flow path is formed to be wider from the manifold side toward the inner peripheral width of the frame around the electrode arrangement part, and a backflow prevention part for preventing the backflow of the electrolytic solution is provided in the middle thereof.

Effect of the Invention

[0018] According to the self-frame of the invention according to claim 1, the groove-shaped flow path formed in the frame provided around the electrode arrangement part and communicating between the manifold and the electrode arrangement part to allow the flow of the electrolytic solution is expanded from the manifold side toward the inner peripheral width of the frame around the electrode arrangement part. Therefore, the flow path through which the electrolytic solution flows between the manifold and the electrode arrangement part is widened to a width that matches the inner peripheral width of the frame around the electrode arrangement part from the manifold side. As a result, the width of the flow path becomes larger in diameter than the manifold, and the length of the flow path also becomes shorter. Thus, the fluid resistance of the electrolytic solution flowing through there can be reduced, and it becomes possible to reduce the pressure loss of the electrolytic solution flowing through the self-frame. Moreover, by providing a backflow prevention part for preventing the backflow of the electrolytic solution in the middle of the flow path, the current loss (shunt current loss) through the electrolytic solution can be reduced. Therefore, it is possible to achieve both reduction of the pressure loss of the circulated electrolytic solution and reduction of the shunt current loss.

[0019] Claim 1 According to the self-frame of the invention according to claim 1, since the flow path is composed of a straight flow path extending in parallel in the width direction of the inner periphery of the frame from the manifold and being narrower in width than the diameter of the manifold and a widened flow path widened from the straight flow path toward the inner peripheral width of the frame,Ma It is possible to suppress deformation of the self-frame around the manifold due to the internal pressure of the electrolytic solution flowing through the manifold and leakage of the electrolytic solution. Further, by providing a backflow prevention portion in the straight flow path, the backflow prevention portion can be formed while suppressing the fluid resistance during the flow of the electrolytic solution to a small value.

[0020] According to the self-frame according to the invention of claim 2, since the flow path gradually raises the groove bottom from the lower side of the frame body parallel to the width direction of the inner circumference within the frame toward the electrode arrangement portion, in the supply-side flow path for supplying the electrolytic solution to the electrode, the cross-sectional area of the flow path for allowing the electrolytic solution to flow between the adjacent diaphragms becomes narrower from the lower side of the frame body toward the electrode arrangement portion. Therefore, in addition to the effect described in claim 1, the diffusibility of the electrolytic solution supplied to the electrode can be enhanced, and the electrolytic solution can be efficiently supplied to the electrode.

[0021] According to the self-frame according to the invention of claim 3, since ribs are formed on the connection side of the flow path with the manifold, the periphery of the manifold is reinforced, and deformation of the self-frame due to the internal pressure of the electrolytic solution flowing through the manifold is prevented. Further, it becomes possible to press the diaphragm disposed between adjacent self-frames in the cell stack and prevent displacement of the diaphragm. Furthermore, it is possible to prevent the adjacent diaphragms from falling into the flow path due to the internal pressure of the electrolytic solution flowing through the manifold. Therefore, in addition to the effect described in claim 1, the durability of the cell stack can be improved.

[0022] According to the cell frame of claim 4, the backflow prevention portion is formed by cutting and bending an upright piece from the surface of the frame, and opening the free end side of the upright piece opposite to the base end on the connection side with the frame, thereby forming a dead end below the upright piece. As a result, the upright state of the upright piece can be changed by the weight of the electrolyte flowing from upstream to downstream, and when a large amount of electrolyte flows from upstream to downstream, the upright state of the upright piece is suppressed, reducing fluid resistance. On the other hand, because the free end side of the upright piece is open, the electrolyte that is trying to backflow flows into the opening and is blocked there, thus preventing backflow of the electrolyte. Therefore, in addition to the effects described in claim 1, the effect of reducing both the pressure loss of the circulating electrolyte and the shunt current loss can be improved.

[0023] Claim 5 According to the cell stack of the invention, in each cell frame comprising it, a groove-shaped flow path formed in a frame provided around the electrode arrangement portion, which connects the manifold and the electrode arrangement portion and allows the electrolyte to flow, is widened from the manifold side toward the width of the inner circumference of the frame surrounding the electrode arrangement portion. Therefore, the flow path through which the electrolyte flows between the manifold and the electrode arrangement section is widened from the manifold side to match the width of the inner circumference of the frame surrounding the electrode arrangement section. As a result, the flow path width is larger than that of the manifold, and the flow path length is also shorter, which reduces the fluid resistance of the electrolyte flowing through it and makes it possible to reduce the pressure loss of the electrolyte flowing through the cell frame. Furthermore, by providing a backflow prevention section in the middle of the flow path to prevent backflow of the electrolyte, current loss through the electrolyte (shunt current loss) can be reduced. Therefore, it is possible to achieve both a reduction in the pressure loss of the circulating electrolyte and a reduction in the shunt current loss.

[0024] Claim 6In the redox flow battery according to the invention, in each cell frame of the cell stack comprising the cell stack, a groove-shaped flow path formed in a frame provided around the electrode arrangement portion, which connects the manifold and the electrode arrangement portion and allows the electrolyte to flow, is widened from the manifold side toward the width of the inner circumference of the frame surrounding the electrode arrangement portion. Therefore, the flow path through which the electrolyte flows between the manifold and the electrode arrangement section is widened from the manifold side to match the width of the inner circumference of the frame surrounding the electrode arrangement section. As a result, the flow path width is larger than that of the manifold, and the flow path length is also shorter, which reduces the fluid resistance of the electrolyte flowing through it and makes it possible to reduce the pressure loss of the electrolyte flowing through the cell frame. Furthermore, by providing a backflow prevention section in the middle of the flow path to prevent backflow of the electrolyte, current loss through the electrolyte (shunt current loss) can be reduced. Therefore, it is possible to achieve both a reduction in the pressure loss of the circulating electrolyte and a reduction in the shunt current loss. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a partial diagram illustrating the configuration of the cell stack of a redox flow battery according to an embodiment of the present invention. [Figure 2] Figure 2 is a diagram illustrating the cell frame of an embodiment of the present invention. [Figure 3] Figure 3 is an explanatory diagram of one side (positive electrode side) of the cell frame according to an embodiment of the present invention. [Figure 4] Figure 4 is an explanatory diagram of the other side (negative electrode side) of the cell frame according to an embodiment of the present invention. [Figure 5] Figure 5(a) is a cross-sectional view of Figure 3 AA, Figure 5(b) is a cross-sectional view of Figure 3 BB, and Figure 5(c) is a cross-sectional view of Figure 3 CC. [Modes for carrying out the invention]

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the same symbols and reference numerals in the illustration represent the same or corresponding functional parts; therefore, their redundant explanations are omitted here.

[0027] [Embodiment] First, let's explain the general configuration of a redox flow battery. A redox flow battery consists of a tank containing an electrolyte solution in which active material ions are dissolved, a battery cell section (flow-type electrolytic cell) equipped with positive and negative electrodes and a diaphragm 103 separating the positive and negative electrodes, which reacts the electrolyte solution to perform charging and discharging, and a pump, piping, etc., which circulate the electrolyte solution between the tank and the battery cell section. The battery performs charging and discharging by supplying positive electrode electrolyte solution to the positive electrode and negative electrode electrolyte solution to the negative electrode, and simultaneously promoting oxidation and reduction reactions on these positive and negative electrodes.

[0028] The battery cell section, which performs the battery reaction, is composed of a stack of multiple battery cells (single cells) arranged in order to obtain a practical voltage. Each battery cell is composed of a negative electrode and a positive electrode, separated by a diaphragm 103 made of an ion exchange membrane. Electrolyte containing an active material is supplied to each electrode from a tank by a pump, causing an oxidation-reduction reaction that enables charging and discharging.

[0029] The electrolyte is not particularly limited, and any solution (including suspensions and dispersions, and regardless of whether it is in liquid or slurry form) obtained by dissolving an ionic active material that performs oxidation-reduction reactions in an electrically conductive aqueous or non-aqueous solvent can be used. For example, solutions containing metal ion active materials such as iron-chromium (Fe / Cr), vanadium (V / V), and titanium-manganese (Ti / Mn) in an aqueous solvent (e.g., an inorganic solvent such as sulfuric acid or hydrochloric acid), solutions containing non-metallic ions such as bromine, iodine, and quinone-based organic substances as active materials in an aqueous solvent (e.g., an inorganic solvent such as sulfuric acid or hydrochloric acid), solutions containing metal ion active materials such as metal complexes and polyacids in a non-aqueous solvent (e.g., an organic solvent), or solutions containing radical-based or quinone-based organic substances as active materials in an aqueous solvent (e.g., an organic solvent) can be used.

[0030] For active materials, vanadium-based (V / V) electrolytes can be used, for example, an aqueous vanadium sulfate solution. In the case of vanadium-based electrolytes, during charging, current flows into the positive electrode, oxidizing the tetravalent V ions in the positive electrode electrolyte to pentavalent, and reducing the trivalent V ions in the negative electrode electrolyte to divalent, thereby charging the device. During discharge, the reverse reaction occurs, and the electricity is extracted.

[0031] As shown in Figure 1, the cell stack forming the battery cell section is constructed by repeatedly stacking battery cells (the smallest unit, a single cell) each having positive and negative electrodes 101, a cell frame 1 with a channel for circulating electrolyte supplied to the positive and negative electrodes 101, and a diaphragm 103 interposed between the positive and negative electrodes 101.

[0032] The electrodes 101, separated into positive and negative electrodes by a diaphragm 103, are inert electrodes made of carbon material. For example, porous carbon fiber aggregates such as carbon cloth, carbon felt, and carbon paper are used. Examples of carbon fibers include polyacrylonitrile (PAN) carbon fibers, pitch carbon fibers, rayon carbon fibers, and phenolic carbon fibers. However, it is also possible to use granular, spherical, tablet, or pellet-shaped carbon materials.

[0033] As will be described later, the cell frame 1 has an electrode arrangement section 105 on its inner circumference where positive and negative electrodes 101 are arranged, and a resin frame 5 is formed around the electrode arrangement section 105, and the frame 5 is provided with a channel for circulating the electrolyte supplied to the positive and negative electrodes. For example, an ion exchange membrane can be used as the diaphragm 103. The diaphragm 103 only needs to have an area greater than or equal to the area of ​​the electrode 101, but if it is to correspond to an area approximately equal to the area of ​​the cell frame 1, holes for the electrolyte to flow through are provided corresponding to the manifolds 11, 12, 21, and 22 of the cell frame 1. In addition, if it is to correspond to an area approximately equal to the area of ​​the cell frame 1, protective material (support material) not shown may be placed around the diaphragm 103 to protect the flow path of the cell frame 1.

[0034] Typically, in a cell stack forming a battery cell, a pair of current collector plates, which are electrically connected to the positive and negative electrodes 101, are arranged on both sides of the stacking direction when multiple battery cells (single cells) are stacked. The current collector plates are conductive members for inputting and outputting electricity between the battery cells and external equipment. These current collector plates are provided with current-carrying terminals (not shown) for electrically connecting the cell stack to an external power source, for example, by connecting to an external device such as an inverter via lead wires. Furthermore, a stack of multiple battery cells, with a pair of current collector plates positioned on both sides in the stacking direction, can be assembled, for example, by sandwiching it between a pair of end plates and tightening it with a tightening jig. The tightening jig in this case consists, for example, of a tightening shaft that connects a pair of end plates around the stacked battery cells and nuts that are screwed onto both ends of the tightening shaft. When assembling a cell stack by tightening in this way, annular sealing members such as O-rings or flat packings are usually placed between each cell frame 1 to suppress electrolyte leakage. In addition, supply and discharge plates are appropriately interposed between the stacks to supply electrolyte pumped from a tank to the cell frame 1 and to supply and discharge electrolyte discharged from the cell frame 1 to the tank. However, when implementing the present invention, the means by which the stacked battery cells can be assembled as a single unit are not particularly limited.

[0035] Here, the details of the cell frame 1 that constitutes the battery cell of this redox flow battery will be explained with reference to Figures 2 to 5. The cell frame 1 according to this embodiment has an electrode arrangement section 105 in the center of the frame body 5 where an electrode 101 is arranged, and is formed in a substantially rectangular shape with four sides E1, E2, E3, and E4, where two opposing sides on all sides are of the same length.

[0036] The electrode arrangement section 105 is not particularly limited as long as it arranges positive and negative electrodes 101 and does not mix the electrolyte between the positive and negative electrodes. For example, it can be a structure in which the positive and negative electrodes 101 are arranged via a bipolar plate, or the electrodes 101 may be integrally provided on the frame 5. The frame 5 of the cell frame 1 is made of an insulating material such as vinyl chloride, polyethylene, polypropylene, fluorine, epoxy resin, or rubber, and is made of a material that has resistance to electrolytes (chemical resistance, acid resistance, etc.).

[0037] In this embodiment, the cell frame 1 has circular through-holes, known as manifolds 11, 12, 21, and 22, formed at the four corners of the rectangular frame 5 surrounding the electrode arrangement section 105. Specifically, it is provided with a positive electrode side electrolyte supply manifold 11 and a positive electrode side drainage manifold 21 through which the positive electrode electrolyte flows, and a negative electrode side electrolyte supply manifold 12 and a negative electrode side drainage manifold 22 through which the negative electrode electrolyte flows. As a result, when multiple cell frames 1 are stacked, the manifolds 11, 12, 21, and 22 of the frame 5 of each cell frame 1 become continuous, and these manifolds 11, 12, 21, and 22 form a flow path for the electrolyte in the stacking direction.

[0038] In this embodiment, the positive electrode side fluid supply manifold 11, the negative electrode side fluid supply manifold 12, the positive electrode side drainage manifold 21, and the negative electrode side drainage manifold 22 are all formed to the same dimensions and shape, and are symmetrically positioned relative to each other in the left-right and up-down directions with respect to the virtual vertical center line (not shown) and virtual horizontal center line (not shown) of the cell frame 1 as axes of symmetry. The positive electrode side fluid supply manifold 11 and the positive electrode side drainage manifold 21 are diagonally opposite each other on the cell frame 1, and the negative electrode side fluid supply manifold 12 and the negative electrode side drainage manifold 22 are also diagonally opposite each other on the cell frame 1.

[0039] Specifically, the positive electrode side fluid supply manifold 11 and the positive electrode side fluid drainage manifold 21 are located at two diagonal corners of the rectangular cell frame 1 (the corner formed by the intersection of two adjacent sides E1 and E4, and the corner formed by the intersection of two adjacent sides E2 and E3), and the negative electrode side fluid supply manifold 12 and the negative electrode side fluid drainage manifold 22 are located at the other diagonal corners (the corner formed by the intersection of two adjacent sides E1 and E2, and the corner formed by the intersection of two adjacent sides E3 and E4). The positive electrode side fluid supply manifold 11 and the negative electrode side fluid supply manifold 12 are located at two opposing corners on the left and right sides of the lower part of the rectangular cell frame 1, and the positive electrode side drainage manifold 21 and the negative electrode side drainage manifold 22 are located at two opposing corners on the upper part. That is, the positive electrode side fluid supply manifold 11 and the negative electrode side fluid supply manifold 12 are in a symmetrical positional relationship with respect to the vertical center line (not shown) of the cell frame 1 as the axis of symmetry, and the positive electrode side drainage manifold 21 and the negative electrode side drainage manifold 22 are also in a symmetrical positional relationship with respect to the vertical center line (not shown) of the cell frame 1 as the axis of symmetry. On one side of the rectangular cell frame 1, the positive electrode side fluid supply manifold 11 and the negative electrode side fluid drainage manifold 22 are located at two vertically opposing corners, while on the other side, the negative electrode side fluid supply manifold 12 and the positive electrode side fluid drainage manifold 21 are located at two vertically opposing corners.

[0040] Furthermore, a groove-shaped (recessed) positive electrode side inlet channel 31 is formed on the positive electrode side surface of the frame 5 of the cell frame 1, connecting the electrode arrangement section 105 and the positive electrode side liquid supply manifold 11. In addition, a groove-shaped (recessed) positive electrode side outlet channel 41 is formed between the electrode arrangement section 105 and the positive electrode side drainage manifold 21, connecting them. Similarly, a groove-shaped (recess-shaped) negative electrode side introduction channel 32 is formed on the negative electrode side surface of the frame 5, connecting the electrode arrangement section 105 and the negative electrode side liquid supply manifold 12, and a groove-shaped negative electrode side discharge channel 42 is formed, connecting the electrode arrangement section 105 and the negative electrode side drainage manifold 22.

[0041] From here, the positive electrode electrolyte, supplied by a pump from the positive electrode electrolyte tank containing the positive electrode electrolyte, flows through a pipe, passing through the inlets of the electrolyte input / output sections provided at both ends of the cell stack, and through a flow path consisting of a positive electrode side electrolyte supply manifold 11 formed in the frame 5 of each cell frame 1. Furthermore, it flows from the positive electrode side electrolyte supply manifold 11 into a groove-shaped positive electrode side introduction flow path 31 that connects the positive electrode side electrolyte supply manifold 11 and the electrode arrangement section 105, and flows through the positive electrode side introduction flow path 31. The positive electrode electrolyte that has flowed through the positive electrode side introduction flow path 31 then flows into the positive electrode 101 arranged in the electrode arrangement section 105 of the cell frame 1, and a battery reaction takes place on the positive electrode 101. Furthermore, the positive electrode electrolyte that has passed from the bottom to the top of the positive electrode electrode 101 flows through a groove-shaped positive electrode side discharge channel 41 that connects the positive electrode side drainage manifold 21 formed in the frame 5 of each cell frame 1 with the electrode arrangement section 105, and is discharged from the positive electrode side drainage manifold 21. The positive electrode electrolyte discharged from the positive electrode side drainage manifold 21 flows through a channel consisting of the positive electrode side drainage manifold 21 formed in the frame 5 of each cell frame 1, and is returned to the positive electrode electrolyte tank through the outlet of the electrolyte input / output section.

[0042] Similarly, the negative electrode electrolyte supplied by a pump from the negative electrode electrolyte tank containing the negative electrode electrolyte flows through a channel consisting of a negative electrode side electrolyte supply manifold 12 formed in the frame 5 of each cell frame 1, passing through the inlets of the electrolyte input / output sections provided at both ends of the cell stack via a pipe. Furthermore, it flows from the negative electrode side electrolyte supply manifold 12 into a groove-shaped negative electrode side introduction channel 32 that connects the negative electrode side electrolyte supply manifold 12 and the electrode arrangement section 105, and flows through the negative electrode side introduction channel 32. The negative electrode electrolyte that has flowed through the negative electrode side introduction channel 32 then flows into the negative electrode 101 arranged in the electrode arrangement section 105 of the cell frame 1, and a battery reaction takes place on the negative electrode 101. Furthermore, the electrolyte that has passed from the bottom to the top of the negative electrode 101 flows through a groove-shaped negative electrode side discharge channel 42 that connects the negative electrode side drainage manifold 22 formed in the frame 5 of each cell frame 1 with the electrode arrangement section 105, and is discharged from the negative electrode side drainage manifold 22. The negative electrode electrolyte discharged from the negative electrode side drainage manifold 22 flows through a channel consisting of the negative electrode side drainage manifold 22 formed in the frame 5 of each cell frame 1, and is returned to the negative electrode electrolyte tank through the outlet of the electrolyte input / output section.

[0043] Note that the positive electrode side electrolyte supply manifold 11 and the negative electrode side electrolyte supply manifold 12 differ only in the flow path of the positive electrode electrolyte or the negative electrode electrolyte, and their basic structure is the same. Therefore, unless otherwise specified, they will simply be referred to as electrolyte supply manifolds 11 and 12. The same applies to the positive electrode side drainage manifold 21 and the negative electrode side drainage manifold 22. Therefore, unless otherwise specified, they will simply be referred to as drainage manifolds 21 and 22. Furthermore, the positive electrode side inlet channel 31 and the negative electrode side inlet channel 32 are essentially the same in structure, differing only in whether they are for the positive or negative electrode electrolyte. Therefore, unless otherwise specified, they will simply be referred to as inlet channels 31 and 32. The same applies to the positive electrode side discharge channel 41 and the negative electrode side discharge channel 42. Therefore, unless otherwise specified, they will simply be referred to as discharge channels 41 and 42.

[0044] Here, we will explain in more detail the groove-shaped inlet channels 31 and 32 that connect the liquid supply manifolds 11 and 12 with the electrode arrangement section 105, and the groove-shaped discharge channels 41 and 42 that connect the liquid drainage manifolds 21 and 22 with the electrode arrangement section 105.

[0045] In this embodiment, the groove-shaped introduction channels 31 and 32 formed on both the positive and negative electrode sides of the frame 5 consist of a straight introduction channel 33 extending parallel to the width direction of the electrode arrangement section 105 from the liquid supply manifolds 11 and 12, and a wide introduction channel 71 that is continuous with the straight channel 33 and widens in a substantially tapered manner from the bottom to the top, up to the width of the electrode arrangement section 105, that is, the width between the opposing inner edges 53 of the inner circumference of the frame 5 on which the electrode arrangement section 105 is provided.

[0046] In this embodiment, the groove-shaped inlet straight channel 33 connected to the liquid supply manifolds 11 and 12 has a pair of channel-forming walls 33a and 33b on both sides that form the channel, which extend in a straight line parallel to the width direction of the electrode arrangement section 105. That is, they extend in a straight line horizontally (lateral direction) parallel to each other from one liquid supply manifold 11 or 12 side toward the other liquid supply manifold 12 or 11 side, and have a substantially constant channel width. From here, the electrolyte that flows into the straight-line intake channel 33 from the supply manifolds 11 and 12 is guided from one supply manifold 11 or 12 towards the other supply manifold 12 or 11.

[0047] In this embodiment, the length of the inlet straight channel 33, that is, the length extending from one liquid supply manifold 11,12 side toward the other liquid supply manifold 12,11 side, is 1 / 10 to 1 / 5, preferably 1 / 9 to 1 / 6, of the width W2 between the opposing inner circumferential edges 53 of the frame 5 on which the electrode arrangement section 105 is provided. Furthermore, the width of the inlet straight channel 33, that is, the width between the pair of channel-forming walls 33a and 33b on both sides that form the channel, is narrower than the diameter of the liquid supply manifolds 11 and 12.

[0048] In this embodiment, the linear intake channel 33 has multiple ribs 151 formed at the connection end with the supply manifolds 11 and 12. This reinforces the area around the supply manifolds 11 and 12 and prevents deformation of the cell frame 1 due to the internal pressure of the electrolyte flowing through the supply manifolds 11 and 12. In addition, the multiple ribs 151 hold down the diaphragm 103 positioned between adjacent cell frames 1 in the cell stack 100, preventing displacement of the diaphragm 103. Furthermore, the internal pressure of the electrolyte prevents the diaphragm 103 from falling into the recesses of the channels 31, 32, 41, and 42, preventing damage to the diaphragm 103 and extending its lifespan.

[0049] Specifically, as shown in Figure 5(b), the rib 151 of this embodiment is formed by dividing the inlet straight channel 33 into multiple sections and creating a protrusion, which protrudes from the bottom of a groove formed at a position lower than the surrounding surface of the liquid supply manifolds 11 and 12. As a result, the inlet straight channel 33 is divided by the protruding rib 151, forming multiple parallel branch grooves 33c. Therefore, in the linear introduction channel 33 of this embodiment, the electrolyte introduced from the supply manifolds 11 and 12 is rectified by branching into the branch groove 33c and flowing through it. In Figures 3 to 5, three protruding ribs 151 are formed in the straight intake channel 33 at approximately the same height as the channel forming walls 33a and 33b that form the straight intake channel 33. As a result, four parallel branch grooves 33c are formed, each with a depth of less than half the height of the surrounding walls forming the supply manifolds 11 and 12. Therefore, the electrolyte introduced from the supply manifolds 11 and 12 branches into four directions and flows through the branch grooves 33c of the straight intake channel 33. However, when implementing the present invention, it is not limited to three ribs 151, but may be one, two, or four or more.

[0050] Furthermore, in this embodiment, the inlet straight channel 33 is provided with an inlet-side backflow prevention section 60 that prevents backflow of electrolyte on the side opposite to the supply manifolds 11 and 12, where the ribs 151 are provided. As shown in Figures 2 and 5(a), the inlet-side backflow prevention section 60 consists of a deep groove 66 at the bottom of the groove, which is deeper than the branch groove 33c, and an upright piece 65 formed to cover the deep groove 66. The upright piece 65 is formed by cutting out a slit-shaped notch in a part of the frame 5 and raising it, and is formed in a rectangular shape that is thinner than the thickness of the depth of the groove 65. This upright piece 65 is a thin piece with one end of the rectangular shape remaining connected to the frame 5, and is plastically deformed by bending the base end 65a side on the connection side with the frame 5 so that it slopes upward from the base end 65a side toward the free end 65 side on the opposite side, and by making the thickness of the free end 65b side slightly thinner than the base end 65a side, the free end 65b side rises (stands up) higher than the base end 65a side, and stands upright with an upward slope from the base end 65a side toward the free end 65b side.

[0051] Here, the base end 65a side of the upright piece 65 is the upstream side when the electrolyte flows from the fluid supply manifold 11,12 side toward the electrode arrangement section 105 side, and is the side where the rib 151 is formed, while the opposite free end 65b side is the downstream side, and is the side of the wide introduction channel 34. In this embodiment, the inlet-side backflow prevention section 60 has a deep groove 66 whose groove bottom is deeper than the groove bottom 34c of the inlet-side wide channel 34 that follows the inlet straight channel 33 provided with the deep groove 66 and the upright piece 65. An upright piece 65 is provided above the groove bottom of the deep groove 66, inclined upward toward the inlet-side wide channel 34. At this time, the upright piece 65 provided above the groove bottom of the deep groove 66 has its base end 65 side connected to the peripheral wall forming the deep groove 66, while the opposite free end 65b side does not come into contact with the inlet-side wide channel 34, and an opening 67 is formed between the upright piece 65 and the deep groove 66.

[0052] Thus, in this embodiment, in the straight inlet channel 33, an upright piece 65 is formed by cutting diagonally upward from the frame 5 toward the wide inlet channel 34, and below it, a deep groove 66 is provided that is deeper than the groove bottom 34c of the wide inlet channel 34. At the base end 65a of the upright piece 65, it is continuous with the surrounding wall forming the deep groove 66, and the opening of the groove is closed by the upright piece 65. As a result, the electrolyte that flows from the branch groove 33c into the backflow prevention section 60 on the inlet side flows over the upper surface of the upright piece 65 and then flows into the wide inlet channel 34.

[0053] On the other hand, on the free end 65b side of the upright piece 65, that is, on the side of the wide inlet channel 34, an opening 67 is formed between the upright piece 65 and the deep groove 66. As a result, the electrolyte flowing back from the wide inlet channel 34 does not pass over the top surface of the upright piece 65 of the straight inlet channel 33 and flow to the supply manifolds 11 and 12, but instead flows into the opening 67 between the upright piece 65 and the deep groove 66, where it is blocked. This prevents the electrolyte from flowing back from the wide inlet channel 34 to the supply manifolds 11 and 12.

[0054] Furthermore, in this embodiment, the wide introduction channel 34, which is formed continuously from the straight introduction channel 33 with a substantially constant channel width, has a wider channel width than the straight introduction channel 33, extending to the width between opposing inner edges 53 of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. It is a diffusion channel that diffuses the electrolyte from the straight introduction channel 33 and guides it to the electrode 101 of the electrode arrangement section 105.

[0055] In this embodiment, the groove-shaped (recessed) wide introduction channel 34 has a pair of channel-forming walls 34a and 34b on both sides that form it. One of these channel-forming walls 34a is continuous with the channel-forming wall 33a that is further from the electrode placement section 105 side of the pair of channel-forming walls 33a and 33b that form the straight introduction channel 33. The other channel-forming wall 34b is continuous with the other channel-forming wall 33b that is closer to the electrode placement section 105 side in the straight introduction channel 33.

[0056] One of the channel-forming walls 34a of the wide introduction channel 34 is parallel to the width of the electrode placement section 105 and consists of a horizontal section 34as that extends linearly from the channel-forming wall 33a of the straight introduction channel 33, from one side of the liquid supply manifold 11, 12 toward the other side of the liquid supply manifold 12, 11, and an inclined section 34ac that curves from the horizontal section 34as and extends linearly toward one of a pair of inner circumferential edges 53 that face each other in the left-right direction on the inner circumference of the frame 5 surrounding the electrode placement section 105.

[0057] Furthermore, the other flow path forming wall 34b is formed at an acute angle to the flow path forming wall 33b of the introduction straight flow path 33; that is, it bends at an acute angle from the flow path forming wall 33b of the introduction straight flow path 33 and extends linearly toward the other of a pair of inner circumferential edges 53 that face each other in the left-right direction on the inner circumference of the frame 5 surrounding the electrode arrangement section 105, and is formed at an angle to the flow path forming wall 33b that extends horizontally parallel to the width of the electrode arrangement section 105. Furthermore, the inclined portion 34ac of one channel-forming wall 34a and the other channel-forming wall 34b of the wide introduction channel 34 face each other, forming a tapered shape as the distance between them gradually widens toward the electrode placement section 105. In other words, in the wide introduction channel 34, the channel width between the pair of channel-forming walls 34a and 34b is formed to be wide from the lower edge E1 side of the frame 5, which is parallel to the width direction of the electrode placement section 105, toward the electrode placement section 105.

[0058] Furthermore, in this embodiment, as shown in Figure 5(c), the wide introduction channel 34 has a groove bottom 34c that rises from the lower side E1 of the frame 5, which is parallel to the width direction of the electrode arrangement section 105, toward the inner circumferential edge on the electrode arrangement section 105 side, that is, the groove bottom is shallowest at the inner circumferential edge on the electrode arrangement section 105 side. As a result, the cross-sectional area of ​​the electrolyte flow path between the cell frame 1 and the diaphragm 130 gradually narrows from the lower side E1 of the frame 5 toward the electrode arrangement section 105 side, and the flow velocity of the electrolyte gradually increases, thereby improving the diffusivity of the electrolyte supplied to the electrodes 101 of the electrode arrangement section 105. Therefore, the electrolyte can be supplied uniformly to the electrodes 101, making it possible to improve battery efficiency.

[0059] For example, the maximum length L1 of the wide introduction channel 34 in the vertical direction, that is, the distance L1 between the horizontal section 34as parallel to the left-right direction of the electrode arrangement section 105 and the electrode arrangement section 105, is within the range of 0.2 to 0.6 times, preferably 0.2 to 0.5 times, the vertical width L2 between a pair of opposing inner edges perpendicular to the left-right direction in the vertical direction of the inner circumference of the frame 5 surrounding the electrode arrangement section 105, and also within the range of 0.5 to 0.9 times, preferably 0.6 to 0.8 times, the vertical (up-down) frame width of the frame 5, and further within the range of 0.1 to 0.4 times, the width W2 between a pair of opposing inner edges 53 in the left-right direction of the inner circumference of the frame 5. Furthermore, the maximum width of the wide introduction channel 34, which is formed between the inclined portion 34ac and the channel forming wall 34b of the channel forming wall 34a, which are tapered and facing each other, is equal to the width W2 between a pair of inner circumferential edges 53 that face each other in the left-right direction on the inner circumference of the frame 5 surrounding the electrode arrangement section 105.

[0060] Therefore, in the wide introduction channel 34, the maximum vertical width L1 of the channel is, for example, 0.5 to 0.9 times, preferably 0.6 to 0.8 times, the vertical frame width of the frame 5, and the channel length is short. However, the width of the channel is wider than the diameter of the liquid supply manifolds 11 and 12 and widens in a substantially tapered manner toward the electrode arrangement section 105. Since the maximum width coincides with the width W2 between the pair of inner circumferential edges 53 of the frame 5, the electrolyte flowing in from the straight introduction channel 33 diffuses toward the electrode arrangement section 105, and the fluid resistance of the electrolyte flowing through it is small.

[0061] With the configuration of the inlet channels 31 and 32, which consist of an inlet straight channel 33 and an inlet wide channel 34, the electrolyte flowing in from the supply manifolds 11 and 12 first branches off in the branch groove 33c of the inlet straight channel 33, which has a constant width narrower than the diameter of the supply manifolds 11 and 12, and flows into the inlet-side backflow prevention section 60. The flow of electrolyte that flows from the supply manifolds 11 and 12 into the inlet straight channel 33 branches off and then flows together into the inlet-side backflow prevention section 60. In the inlet-side backflow prevention section 60, an upright piece 65 is provided on the upper side of the deep groove 66. At the end opposite to the supply manifold 11, 12 side, i.e., the free end 65b of the upright piece 65 on the wide inlet channel 34 side, there is an opening 67 between the deep groove 66 and the upright piece 65. However, at the base end 65a of the upright piece 65 on the supply manifold 11, 12 side, the upright piece 65 is connected to the deep groove 66, closing the groove. As a result, the electrolyte that flows from the branch groove 33c into the inlet-side backflow prevention section 60 flows over the upper surface of the upright piece 65 and into the wide inlet channel 34. Since the upright piece 65, which is formed by cutting and bending, can change its upright state depending on the weight, flow rate, flow velocity, and internal pressure of the electrolyte flowing into it, the electrolyte can smoothly pass over the upper surface of the upright piece 65 and flow into the wide inlet channel 34.

[0062] In the wider introduction channel 34 that follows the straight introduction channel 33, one channel forming wall 34a is composed of a horizontal section 34as that extends continuously from the channel forming wall 33a of the straight introduction channel 33 and parallel to the width direction of the electrode arrangement section 105, and an inclined section 34ac that curves from the horizontal section 34as and extends linearly toward one of a pair of opposing inner circumferential edges 53 on the inner circumference of the frame 5 surrounding the electrode arrangement section 105 in the left-right direction. The other channel forming wall 34b is continuously from the channel forming wall 33b of the straight introduction channel 33, bends at an acute angle, and extends linearly toward the other of a pair of inner circumferential edges 53 on the inner surface of the frame 5. As a result, the wide inlet channel 34 has a wider channel width than the straight inlet channel 33, which has a constant width narrower than the diameter of the liquid supply manifolds 11 and 12. Therefore, the electrolyte that has passed through the upright piece 65 of the straight inlet channel 33 and flowed into the wide inlet channel 34 diffuses in the width direction of the frame 5, that is, in the width direction perpendicular to the vertical direction, which is the flow direction of the electrolyte that flows from bottom to top, and flows towards the electrode arrangement section 105.

[0063] Thus, in the cell frame 1 of this embodiment, the wide introduction channel 34 is widened to a maximum of the width between a pair of opposing inner circumferential edges 53 of the frame 5 in the left-right direction, and the electrolyte is diffused and circulated in the width direction of the electrode arrangement section 105 with a channel width wider than the diameter of the fluid supply manifolds 11 and 12. Because the channel length is short, the electrolyte can be circulated with little fluid resistance. Furthermore, because the inclined portion 34ac of the channel-forming wall 34b in the wide inlet channel 34 is curved, the direction of the electrolyte can be smoothly changed, thus reducing fluid resistance. Therefore, the electrolyte can be circulated between the cell stack and the electrolyte tank with minimal pressure loss, and the load on the pump supplying the electrolyte from the electrolyte tank to the cell stack can also be reduced. Consequently, the electrolyte flow rate can be increased with less pump load, improving the reaction efficiency of the electrolyte and increasing energy efficiency.

[0064] In particular, in this embodiment, the groove bottom 34c of the wide introduction channel 34 rises from the lower side E1 of the frame 5, which is parallel to the width direction of the electrode arrangement section 105, toward the electrode arrangement section 105. This gradually narrows the cross-sectional area of ​​the electrolyte flow path between the cell frame 1 and the diaphragm 130, from the lower side E1 of the frame 5 toward the electrode arrangement section 105. As a result, the flow velocity of the electrolyte can be gradually increased from the lower side E1 of the frame 5 toward the electrode arrangement section 105, thereby increasing the diffusivity of the electrolyte supplied to the electrode 101 of the electrode arrangement section 105, and enabling greater diffusion of the electrolyte in the width direction of the electrode arrangement section 105. In other words, the electrolyte can be supplied uniformly and evenly in the width direction of the electrode 101. Therefore, it is possible to increase the reaction efficiency of the electrolyte.

[0065] Furthermore, in the wide introduction channel 34, the electrolyte diffuses toward the electrode arrangement section 105, and its maximum width coincides with the width W2 between a pair of opposing inner circumferential edges 53 of the frame 5 surrounding the electrode arrangement section 105. This allows for uniform supply of the electrolyte in the width direction of the electrode 101 of the electrode arrangement section 105, enabling uniform diffusion and penetration over a wide area of ​​the electrode 101. As a result, the battery reaction is more likely to occur uniformly over a wide area of ​​the electrode, which increases the reaction efficiency of the electrolyte and reduces internal resistance. Therefore, the output of redox flow batteries can be improved.

[0066] Furthermore, in the cell frame 1 of this embodiment, in the introduction-side backflow prevention section 60 provided in the introduction straight channel 33, an upright piece 65 is formed by cutting and bending it diagonally upward from the frame 5 toward the introduction-side wide channel 34, and below it, a deep groove 66 is provided that is deeper than the groove bottom 34c of the introduction-side wide channel 34, and at the free end 65b of the upright piece 65 on the introduction-side wide channel 34 side, an opening 67 is formed between the deep groove 66 and the upright piece 65, so that the electrolyte that tries to backflow from the introduction-side wide channel 34 side falls into the deep groove 66 through the opening 67 between the deep groove 66 and the upright piece 65 and becomes a dead end there, and does not backflow to the liquid supply manifold 11,12 side by passing over the top surface of the upright piece 65. In particular, in this embodiment, the free end 65b on the opposite side of the upright piece 65 does not come into contact with the wide intake channel 34 even when it is in a horizontal position, and a small gap is created between them. This prevents the electrolyte from flowing back over the upper surface of the upright piece 65, even if the flow velocity and pressure of the electrolyte attempting to flow back from the wide intake channel 34 side become large.

[0067] Therefore, the formation of this inlet-side backflow prevention section 60 prevents the electrolyte from flowing back from the wide inlet-side channel 34 to the supply manifolds 11 and 12 even when the pressure of the circulation pump drops. Furthermore, below the upright piece 65, a deep groove 66 is formed which is deeper than the groove bottom 34c on the straight inlet channel 33 side of the wide inlet-side channel 34, thereby preventing the electrolyte from leaking out of the channel. Thus, in this embodiment, backflow of the electrolyte can be prevented, resulting in less shunt current loss and making it less likely for short-circuit current to flow between battery cells due to backflow.

[0068] In the cell frame 1 of this embodiment, the electrolyte flows in from the supply manifolds 11 and 12, flows through the introduction channels consisting of an introduction straight channel 33 and an introduction wide channel 34 from the bottom to the top of the cell frame 1, and flows to the bottom of the electrode 101 of the electrode arrangement section 105, flows over the electrode 101 from the bottom to the top, and flows from the top of the electrode 101 into the discharge channels 41 and 42 which are opposite to the introduction channels 31 and 32.

[0069] Here, the discharge channels 41 and 42 in this embodiment have a flow channel structure symmetrical to that of the introduction channels 31 and 32. That is, the groove-shaped discharge channels 41 and 42 formed on the front and back surfaces of the frame 5 and connecting the drainage manifolds 21 and 22 with the electrode arrangement section 105 are formed from a straight discharge channel 33 extending parallel to the width direction of the electrode arrangement section 105 from the drainage manifolds 21 and 22, and a wide discharge channel 44 that is continuous with the straight discharge channel 33 and widens to the width between opposing inner edges 53 of the inner circumference of the frame 5 around the electrode arrangement section 105, that is, the channel is widened in a substantially tapered manner from top to bottom. From the perspective of the electrolyte flow direction, the wide discharge channel 44 is formed from a wide discharge channel 44 that narrows in a tapered manner from bottom to top, and a straight discharge channel 43 that is continuous with the wide discharge channel 44 and guides the electrolyte from the wide discharge channel 44 to the drainage manifolds 21 and 22.

[0070] The groove-shaped wide discharge channels 44 formed on the front and back surfaces of the frame 5 are channels that gradually narrow from the widest channel width corresponding to the width W2 between a pair of opposing inner circumferential edges 53 of the frame 5 surrounding the electrode arrangement section 105, upwards, that is, toward the upper edge E3 side of the frame, to converge the electrolyte that has passed through the electrodes 101 of the electrode arrangement section 105 and guide it toward the straight discharge channel 43 with a substantially constant channel width.

[0071] In the wide discharge channel 44 of this embodiment, one of the pair of channel forming walls 44a and 44b that form it is continuous with the channel forming wall 43a that is further from the electrode placement section 105 side of the pair of channel forming walls 43a and 43b that form the straight discharge channel 43, and the other channel forming wall 44b is continuous with the other channel forming wall 44b that is closer to the electrode placement section 105 side in the straight discharge channel 43.

[0072] Similar to the wide inlet channel 34, one channel-forming wall 44a of the wide discharge channel 44 is parallel to the width of the electrode placement section 105 and consists of a horizontal section 44as that extends linearly from the channel-forming wall 43a of the straight discharge channel 43 from one drainage manifold 21, 22 side toward the other supply manifold 22, 21 side, and an inclined section 44ac that curves from the horizontal section 44as and extends linearly toward one of a pair of inner circumferential edges 53 that face each other in the left-right direction on the inner circumference of the frame 5 surrounding the electrode placement section 105. Specifically, one of the flow path forming walls 44a of the wide discharge flow path 44 consists of an inclined section 44ac that extends upward from one side of a pair of opposing inner circumferential edges 53 of the frame 5 surrounding the electrode arrangement section 105 in the left-right direction, and then curves after extending diagonally in a straight line toward the center in the left-right direction, and a horizontal section 44as that is continuous with the inclined section 44ac and extends linearly laterally toward the drainage manifolds 21 and 22.

[0073] Furthermore, the other channel-forming wall 44b of the wide discharge channel 44 is formed at an acute angle with respect to the channel-forming wall 43b of the straight discharge channel 43. That is, it bends at an acute angle from the channel-forming wall 43b of the straight discharge channel 43 and extends linearly toward the other of a pair of inner circumferential edges 53 that face each other in the left-right direction on the inner circumference of the frame 5 surrounding the electrode arrangement section 105, and is formed at an angle with respect to the channel-forming wall 43b that extends horizontally parallel to the width of the electrode arrangement section 105. In other words, the other channel-forming wall 44b of the wide discharge channel 44 extends diagonally upward in a straight line from the other end side in the lateral direction of the electrode arrangement section 105 toward the center in the width direction, and is formed at an acute angle with respect to the channel-forming wall 43b of the straight discharge channel 43.

[0074] Furthermore, the inclined portion 44ac of one channel-forming wall 44a of the wide discharge channel 44 and the other channel-forming wall 44b face each other, forming a tapered shape with the distance between them gradually widening toward the electrode placement section 105. In other words, in the wide discharge channel 44, the channel width between the pair of channel-forming walls 44a and 44b is formed in a tapered shape, gradually narrowing toward the upper edge E3 of the frame 5 parallel to the width direction of the electrode placement section 105, starting from the electrode placement section 105. The channel width of the wide discharge channel 44 is the same as the dimensions of the wide inlet channel 34.

[0075] Therefore, in the wide discharge channel 44, the maximum width corresponds to the width between the pair of inner circumferential edges 53 of the frame 5, and it is formed to gradually narrow in a substantially tapered manner toward the upper edge E3 side of the frame 5 opposite to the electrode arrangement section 105 side. As a result, the electrolyte that flows from the top of the electrodes 101 of the electrode arrangement section 105 into the wide discharge channel 44 converges and flows toward the straight discharge channel 43 side. However, because the maximum width corresponds to the width between the pair of inner circumferential edges 53 of the frame 5, and because the channel is wide and short, the fluid resistance of the electrolyte flowing through it is small.

[0076] Furthermore, in this embodiment, the straight discharge channel 43, which is formed continuously from the wide discharge channel 44 and connected to the drainage manifolds 21 and 22, has a pair of channel-forming walls 43a and 43b on both sides that form the channel, extending linearly parallel to the width direction of the electrode arrangement section 105. That is, they extend linearly in the horizontal direction (lateral direction) parallel to each other from one drainage manifold 21 and 22 side to the other drainage manifold 22 and 21 side, and has a substantially constant channel width. From this point onward, the electrolyte that flows from the wide discharge channel 44 into the straight discharge channel 43 is guided toward the drainage manifolds 21 and 22.

[0077] In this embodiment, the length of the discharge straight channel 43 is the same as the length of the introduction straight channel 33, and the length extending from one drainage manifold 21, 22 side toward the other opposing drainage manifold 22, 21 side is about 1 / 10 to 1 / 5, preferably about 1 / 9 to 1 / 6, of the width W2 between the opposing inner circumferential edges 53 of the frame 5 on which the electrode arrangement section 105 is provided. Furthermore, the width of the discharge straight channel 43, that is, the width between the pair of channel-forming walls 43a and 43b on both sides that form the channel, is narrower than the diameter of the drainage manifolds 21 and 22.

[0078] In this embodiment, the discharge linear channel 43 is also provided with a discharge-side backflow prevention unit 70 to prevent backflow of the electrolyte, similar to the introduction linear channel 33. The discharge-side backflow prevention section 70 has the same configuration as the inlet-side backflow prevention section 60, and as shown in Figures 2 and 5(a), it consists of a deep groove 76 at the bottom of the groove, which is even deeper than the branch groove 43c, and an upright piece 75 formed to cover the deep groove 76. This upright piece 75 is also formed by cutting out a slit-shaped notch in a part of the frame 5 and raising it, and is formed in a rectangular shape that is thinner than the thickness of the depth of the groove 75. This upright piece 75 is a thin rectangular section with one end still connected to the frame 5. The base end 75a on the side connected to the frame 5 is bent and plastically deformed so that it slopes upward from the base end 75a towards the opposite free end 75. Furthermore, the thickness of the free end 75b is made slightly thinner than that of the base end 75a. As a result, the free end 75b rises higher (stands up) than the base end 75a, and it stands upright, sloping upward from the base end 75a towards the free end 75b.

[0079] In the discharge side backflow prevention section 70, the base end 65a side of the upright piece 75 is the upstream side when the electrolyte flows from the electrode arrangement section 105 side toward the drainage manifold 22,21 side, and is the wide discharge channel 44 side, while the opposite free end 75b side is the downstream side, and is the side where the rib 151 is formed. In this embodiment, the discharge side backflow prevention section 70 has a deep groove 76 whose groove bottom is deeper than the groove bottom on the discharge straight channel 43 side of the discharge side wide channel 44, and an upright piece 75 is provided above the groove bottom of the deep groove 76, which is inclined upward toward the drain manifolds 22 and 21. At this time, the upright piece 75 provided above the deep groove 76 has its base end 75 side connected to the peripheral wall forming the deep groove 76, while the opposite free end 75b side does not come into contact with the branch groove 43c side forming the rib 151, and an opening 77 is formed between the upright piece 75 and the deep groove 76.

[0080] Thus, in this embodiment, in the straight discharge channel 43, an upright piece 75 is formed by cutting and bending it diagonally upward from the frame 5 toward the drain manifolds 22 and 21. Below it, a deep groove 76 is provided that is deeper than the bottom of the downstream branch groove 43c. The base end 75a of the upright piece 75 is continuous with the surrounding wall forming the deep groove 76, and the opening of the groove is closed by the upright piece 75. As a result, the electrolyte that flows from the wide discharge channel 44 into the straight discharge channel 43 flows over the upper surface of the upright piece 75 and flows into the subsequent branch groove 43c.

[0081] On the other hand, on the free end 75b side of the upright piece 75 opposite to the wide discharge channel 44 side, an opening 77 is formed between the upright piece 75 and the deep groove 76. As a result, the electrolyte flowing back from the drain manifolds 22 and 21 side does not pass over the top surface of the upright piece 75 of the straight discharge channel 43 and flow to the wide discharge channel 44 side, but instead flows into the opening 77 between the upright piece 75 and the deep groove 76, where it is blocked. This prevents the electrolyte from flowing back from the drain manifolds 22 and 21 side to the wide discharge channel 44 side.

[0082] Furthermore, in the discharge straight channel 43 of this embodiment, multiple ribs 151 are formed between the drain manifolds 22, 21 and the discharge side backflow prevention section 70, that is, on the connection end side with the drain manifolds 22, 21. This reinforces the area around the drain manifolds 22, 21 and prevents deformation of the cell frame 1 due to the internal pressure of the electrolyte flowing through the drain manifolds 22, 21. In addition, damage to the diaphragm 103, which is placed between adjacent cell frames 1 in the cell stack, due to falling into the recess of the discharge straight channel 43 by the internal pressure of the electrolyte, etc., is prevented, and the lifespan of the diaphragm 103 is extended. Moreover, by holding down the diaphragm 10, which is placed between adjacent cell frames 1 in the cell stack, displacement of the diaphragm 103 can be prevented, thereby preventing a decrease in the charge / discharge rate due to the mixing of positive and negative electrolytes.

[0083] In the discharge straight channel 43, as shown in Figure 5(b), the ribs 151 are formed as protrusions by dividing the discharge straight channel 43 into multiple sections, and are positioned at the bottom of grooves lower than the surrounding surfaces of the drainage manifolds 22 and 21. As a result, the discharge straight channel 43 is divided by the protruding ribs 151, forming multiple parallel branch grooves 43c. Therefore, in the straight discharge channel 43 of this embodiment, the electrolyte that has passed over the upper surface of the upright piece 75 of the discharge-side backflow prevention section 70 is rectified by branching into the branch groove 43c and flowing through it, and is then discharged from the drain manifolds 22 and 21. In Figures 3 to 5, three protruding ribs 151 are formed in the discharge straight channel 43 at approximately the same height as the channel forming walls 43a and 43b that form the discharge straight channel 43. As a result, four parallel branch grooves 43c are formed, each with a depth of less than half the height of the surrounding walls forming the drain manifolds 22 and 21. Therefore, the electrolyte that passes over the upper surface of the upright piece 75 of the discharge side backflow prevention section 70 branches into four and flows into the branch grooves 43c of the discharge straight channel 43.

[0084] With the configuration of the discharge channels 41 and 42, which consist of a wide discharge channel 44 and a straight discharge channel 43 formed on the front and back surfaces of the cell frame 1, the electrolyte that has passed from the electrode 101 of the electrode arrangement section 105 from bottom to top flows into the wide discharge channel 44, whose maximum width corresponds to the width W2 between a pair of inner circumferential edges 53 of the frame 5. In the wide discharge channel 44, an inclined section 44ac extends diagonally in a straight line from one of the pair of inner circumferential edges 53 of the frame 5 toward the upper edge E3 of the frame 5 and then curves, and a horizontal section 44as extends continuously from the inclined section 44ac parallel to the width direction of the electrode arrangement section 105. The other channel forming wall 44b extends diagonally in a straight line from the other of the pair of inner circumferential edges 53 of the frame 5 and is formed at an acute angle with respect to the channel forming wall 43a of the straight discharge channel 43. Thus, the wide discharge channel 44 is wider than the diameter of the drainage manifolds 22 and 21, but it gradually narrows from the width between the pair of inner circumferential edges 53 of the frame 5 towards the upper edge E3 of the frame 5. As a result, the electrolyte that has passed through the electrode 101 converges in the wide discharge channel 44 and is guided upward from the electrode placement section 105, flowing into the discharge backflow prevention section 70 of the straight discharge channel 43, which is continuous with the wide discharge channel 44 and has a constant width narrower than the diameter of the drainage manifolds 22 and 21.

[0085] In the discharge side backflow prevention section 70, an upright piece 75 is provided above the deep groove 76. On the free end 75b side of the upright piece 75 on the drain manifold 22,21 side, there is an opening 77 between the deep groove 76 and the upright piece 75. However, on the base end 75a side on the discharge side wide flow channel 44 side, the upright piece 75 is connected to the deep groove 76, closing the groove. As a result, the electrolyte from the discharge side wide flow channel 44 flows over the upper surface of the upright piece 75 and into the branch groove 43c side. Since the upright piece 75, which is formed by cutting and bending, can change its upright state depending on the weight, flow rate, flow velocity, internal pressure, etc., of the electrolyte flowing into it, the electrolyte can smoothly pass over the upper surface of the upright piece 75 and flow into the branch groove 43c side. The electrolyte that has passed over the upper surface of the upright piece 75 of the straight discharge channel 43 is then branched in the subsequent branch groove 43c, and these are discharged together from the drainage manifolds 22 and 21.

[0086] Thus, in the cell frame 1 of this embodiment, even in the wide discharge channel 44, the maximum width corresponds to the width between a pair of opposing inner circumferential edges 53 in the left-right direction on the inner circumference of the frame 5 surrounding the electrode arrangement section 105. Since the channel width is wider than the diameter of the drainage manifolds 22 and 21, and the channel length is short, the electrolyte can be circulated from the electrode arrangement section 105 side toward the drainage manifolds 21 and 22 with minimal fluid resistance. Furthermore, even in the wide discharge channel 44, the curved inclined portion 44ac of the channel-forming wall 44b allows for a smooth change in the direction of the electrolyte, thus reducing fluid resistance.

[0087] Therefore, the electrolyte can be circulated between the cell stack and the electrolytic tank with minimal pressure loss, and the load on the pump that supplies the electrolyte from the electrolyte tank to the cell stack can also be reduced. Consequently, the flow rate of the electrolyte can be increased with less pump load, improving the reaction efficiency of the electrolyte and increasing energy efficiency.

[0088] Furthermore, since the maximum width of the wide discharge channel 44 matches the width W2 between a pair of opposing inner circumferential edges 53 in the left-right direction of the frame 5 surrounding the electrode arrangement section 105, the electrolyte after the battery reaction at the electrode 101 is quickly discharged into the wide discharge channel 44, thereby improving the charge and discharge efficiency.

[0089] Furthermore, in the cell frame 1 of this embodiment, in the discharge-side backflow prevention section 70 provided in the discharge straight flow path 43, an upright piece 75 is formed by cutting and bending it diagonally upward from the frame 5 toward the drain manifold 21,22 side, and below it, a deep groove 76 is provided that is deeper than the bottom of the branch groove 43c, and at the free end 75b of the upright piece 75 on the drain manifold 21,22 side, an opening 77 is formed between the deep groove 76 and the upright piece 75, so that the electrolyte that tries to backflow from the drain manifold 21,22 side falls into the deep groove 76 through the opening 77 between the deep groove 76 and the upright piece 75 and becomes a dead end there, and does not backflow to the discharge-side wide flow path 44 side by passing over the upper surface of the upright piece 75. In particular, in this embodiment, the free end 75b on the opposite side of the upright piece 75 does not come into contact with the branch groove 43c even when it is in a horizontal position, and a small gap is created between them. This prevents the electrolyte from flowing back over the upper surface of the upright piece 75, even if the flow velocity and pressure of the electrolyte attempting to flow back from the drain manifold 21, 22 side become large.

[0090] Therefore, the formation of this discharge-side backflow prevention section 70 prevents the electrolyte from flowing back into the wide discharge channel 44 from the drain manifolds 21 and 22 even when the pressure of the circulation pump drops. Furthermore, below the upright piece 75, a deep groove 77 is formed which is deeper than the bottom of the branch groove 43c, preventing the electrolyte from leaking out of the channel. Thus, in this embodiment, backflow of the electrolyte can be prevented, resulting in low shunt current loss, and also making it less likely for short-circuit current to flow between battery cells due to backflow.

[0091] As described above, according to the cell frame 1 of this embodiment, groove-shaped inlet channels 31, 32 and outlet channels 41, 42, which are formed on the front and back surfaces of the frame 5 surrounding the electrode arrangement section 105 and connect the manifolds 11, 12, 21, 22 provided at the four corners of the frame 5 to the electrode arrangement section 105, and allow the electrolyte to flow, are widened from the manifold 11, 12, 21, 22 side toward the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. Therefore, in the inlet channels 31, 32, the channel width is wider than the diameter of the supply manifolds 11, 12, and the electrolyte flowing in from the supply manifolds 11, 12 is diffused and circulated toward the width direction of the electrode arrangement section 105, allowing the electrolyte to flow with less fluid resistance. Furthermore, in the discharge channels 41 and 42, the maximum width corresponds to the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105, and the channel width is wider than the diameter of the drainage manifolds 22 and 21. Since the fluid flows from the electrode arrangement section 105 side toward the drainage manifolds 21 and 22, the electrolyte can be circulated with low fluid resistance. Therefore, the electrolyte can be circulated between each cell frame 1 of the cell stack 100 and the electrolyte tank with minimal pressure loss, and the load on the pump that supplies the electrolyte from the electrolyte tank to the cell stack can also be reduced. Consequently, the flow rate of the electrolyte can be increased with less pump load, improving the reaction efficiency of the electrolyte and increasing energy efficiency.

[0092] Furthermore, in the middle of the inlet channels 31, 32 and the discharge channels 41, 42, backflow prevention sections 60, 70 are provided, which are formed by cutting and bending from the surface of the frame 5, with the free ends 65b, 75b opposite to the base ends 65a, 75a on the connection side with the frame 5 being open 67, 77, and deep grooves 66, 76 forming dead ends below the upright pieces 65, 75. As a result, in the introduction channels 31 and 32, in the flow direction of the electrolyte supplied from the supply manifolds 11 and 12 to the electrodes 101 of the electrode arrangement section 105, the electrolyte can flow along the upper surface of the upright piece 65 from the base end 65a to the free end 65b. At the same time, the upright piece 65 has an opening 67 at the free end 65b, forming dead ends 66 and 76 below the upright piece 65. Therefore, any electrolyte attempting to flow back flows into the opening 67 and is stopped at the dead end 66 below the upright piece 65. Consequently, it does not flow from the free end 65b to the base end 65a on the upper surface of the upright piece 65, thus preventing backflow of the electrolyte. Furthermore, in the discharge channels 41 and 42, in the direction of electrolyte flow where the electrolyte that has passed through the electrode 101 is discharged toward the drainage manifolds 21 and 22, by setting the free end 75b side of the upright piece 75 toward the drainage manifolds 21 and 22, the electrolyte can flow from the base end 75a side toward the free end 75b side along the upper surface of the upright piece 75. At the same time, an opening 77 is formed at the free end 75b side of the upright piece 75, creating a dead end 76 below the upright piece 75. As a result, any electrolyte attempting to flow back flows in through the opening 77 and is blocked there, preventing it from flowing from the free end 75b side toward the base end 75a side along the upper surface of the upright piece 75, thus preventing backflow. In particular, in this embodiment, the plastic deformation of the upright pieces 65 and 75 in a direction inclined from the base ends 65a and 75a makes it difficult for the openings 67 and 77 on the free ends 65b and 75b of the upright pieces 65 and 75 to close. This ensures that the electrolyte, which is trying to flow back even under negative pressure, flows into the deep grooves 66 and 76 from the lower openings 67 and 77 of the upright pieces 66 and 75, and reliably prevents it from passing over the upper surface of the upright pieces 65 and 75 from the free ends 65a and 75a to the base ends 65a and 75a. Therefore, current loss through the electrolyte (shunt current loss) can be reduced.

[0093] Furthermore, the dead-end section 66 in this embodiment consists of a deep groove 66 that is deeper than the groove bottom 34c of the wide introduction channel 34 on the free end 65b side of the upright piece 65, and the dead-end section 76 also consists of a deep groove 76 whose groove bottom is deeper than the branch groove 43c on the free end 75 side of the upright piece 75, so that the electrolyte that is trying to backflow does not easily leak out of the channel at the backflow prevention sections 60 and 70.

[0094] Thus, according to the cell frame 1 of this embodiment, the pressure loss of the circulating electrolyte can be reduced, and the shunt current loss can also be reduced. Furthermore, by reducing the fluid resistance of the electrolyte flowing through the inlet channels 31, 32 and the outlet channels 41, 42 in this way, a high flow rate of electrolyte can be secured without requiring a high-power pump. In addition, because the inlet channels 31, 32 and the outlet channels 41, 42 are widened to a width corresponding to the width of the electrode arrangement section 105, the electrolyte diffuses on the supply side, and on the discharge side, the electrolyte after the battery reaction is quickly discharged into the outlet channels 41, 42. This allows for a uniform flow of electrolyte through electrode 101, thereby increasing the battery's reaction efficiency. Consequently, it enables higher battery output. Furthermore, by eliminating the need for a high-power pump, the overall energy efficiency of the redox flow battery can be improved.

[0095] In addition, according to the cell frame 1 of this embodiment, in the introduction channels 31 and 32 through which the electrolyte flows, the bottom of the groove rises from the lower side E1 of the frame 5, which is parallel to the width direction of the electrode arrangement section 105, toward the electrode arrangement section 105. As a result, the cross-sectional area of ​​the electrolyte flow path between the cell frame 1 and the diaphragm 130, flowing through the introduction channels 33 and 34 of the cell frame 1, gradually narrows from the lower side E1 of the frame 5 toward the electrode arrangement section 105. This allows the flow velocity of the electrolyte to gradually increase from the lower side E1 of the frame 5 toward the electrode arrangement section 105, thereby increasing the diffusivity of the electrolyte supplied to the electrode 101 of the electrode arrangement section 105, and allowing the electrolyte to diffuse more in the width direction of the electrode arrangement section 105. Therefore, the electrolyte can be supplied uniformly and evenly in the width direction of the electrode 101, and the reaction efficiency of the electrolyte can be increased.

[0096] As described above, the cell frame 1 of the above embodiment is a cell frame 1 consisting of an electrode arrangement section 105 for arranging positive and negative electrodes, and a frame body 5 provided around the electrode arrangement section 105. The frame body 5 has flow paths 31, 32, 41, 42 through which the electrolyte flows, connecting manifolds 11, 12, 21, 22 formed penetrating its four corners to the electrode arrangement section 105. The flow paths 31, 32, 41, 42 widen from the manifold 11, 12, 21, 22 side of the frame body toward the width of the inner circumference where the electrode arrangement section 105 is provided, and backflow prevention sections 60, 70 are provided along the way to prevent backflow of the electrolyte.

[0097] According to the cell frame 1 of the above embodiment, groove-shaped flow paths 31, 32, 41, 42, which are formed in the frame 5 provided around the electrode arrangement section 105 and connect the manifolds 11, 12, 21, 22 and the electrode arrangement section 105, and through which the electrolyte flows, are widened from the manifolds 11, 12, 21, 22 toward the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. In this way, the flow paths 31, 32, 41, and 42 that circulate the electrolyte between the manifolds 11, 12, 21, and 22 and the electrode arrangement section 105 are widened from the manifold 11, 12, 21, and 22 side to match the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. As a result, the width of the flow paths 31, 32, 41, and 42 is larger in diameter than the manifolds 11, 12, 21, and 22, and the flow path length is also shorter. This reduces the fluid resistance of the electrolyte circulating through them, making it possible to reduce the pressure loss of the electrolyte supplied to the cell frame 1. Furthermore, by providing backflow prevention sections 60 and 70 in the middle of the flow paths 31, 32, 41, and 42 to prevent backflow of the electrolyte, current loss (shunt current loss) through the electrolyte can be reduced. Therefore, the electrolyte can be supplied to the electrodes with low pressure loss, and shunt current loss can also be reduced. This makes it possible to increase the output power of redox flow batteries.

[0098] Furthermore, according to the cell frame 1 of the above embodiment, the channels 31 and 32 have groove bottoms that rise from the lower side E1 of the frame 5, which is parallel to the width direction of the inner circumference of the frame 5, toward the electrode placement section 105. As a result, in the introduction channels 31 and 32 that supply electrolyte to the electrode 101, the cross-sectional area of ​​the channels through which the electrolyte flows between the adjacent diaphragm 103 narrows toward the electrode placement section 105 from the lower side E1 of the frame 5. Therefore, in addition to the effects described in claim 1, the diffusivity of the electrolyte supplied to the electrode 101 can be increased, and the electrolyte can be supplied to the electrode efficiently.

[0099] Furthermore, according to the cell frame 1 of the above embodiment, ribs 151 are formed on the connection side of the flow paths 31, 32, 41, and 42 with the manifolds 11, 12, 21, and 22, thereby reinforcing the area around the manifolds 11, 12, 21, and 22 and preventing deformation of the cell frame 1 due to the internal pressure of the electrolyte flowing through the manifolds 11, 12, 21, and 22. In addition, it is possible to prevent adjacent diaphragms 103 from falling into the flow paths 31, 32, 41, and 42 and being damaged due to the internal pressure of the electrolyte flowing through the manifolds 11, 12, 21, and 22. Therefore, the durability of the cell stack can be improved. Furthermore, it is possible to prevent displacement of the diaphragms 103 by holding down the diaphragms 103 that are positioned between adjacent cell frames 1 in the cell stack. Therefore, it is possible to prevent a decrease in the charge / discharge rate due to the mixing of positive and negative electrolytes. Furthermore, it is possible to prevent foreign matter from reaching the electrode 101.

[0100] In addition, according to the cell frame 1 of the above embodiment, the backflow prevention sections 60 and 70 are formed by cutting and bending upright pieces 65 and 75 from the surface of the frame 5. The free ends 65b and 75b of the upright pieces 65 and 75, opposite to the base ends 65a and 75a that connect to the frame 5, are opened, and deep grooves 66 and 67 are formed below the upright pieces 65 and 75 as dead ends. As a result, the upright state of the upright pieces 65 and 75 can be changed by the weight of the electrolyte flowing from upstream to downstream. When a large amount of electrolyte flows from upstream to downstream, the upright state of the upright pieces 65 and 75 is suppressed, reducing fluid resistance. On the other hand, since the free ends 65b and 75b of the upright pieces 65 and 75 form openings 67 and 77, the electrolyte that is trying to backflow flows into these openings 67 and 77 and is blocked there, thus preventing backflow of the electrolyte. Therefore, it is possible to improve the effect of achieving both a reduction in the pressure loss of the circulating electrolyte and a reduction in the shunt current loss.

[0101] Furthermore, according to the cell frame 1 of the above embodiment, the flow paths 31, 32, 41, and 42 are composed of straight flow paths 33 and 43 that extend parallel to the width direction of the inner circumference of the frame 5 from the manifolds 11, 12, 21, and 22 and are narrower than the diameter of the manifolds 11, 12, 21, and 22, and wide flow paths 34 and 44 that widen from the straight flow paths 33 and 43 toward the width of the inner circumference of the frame 5. Therefore, deformation of the cell frame 1 around the manifolds 11, 12, 21, and 22 due to the internal pressure of the electrolyte flowing through the manifolds 11, 12, 21, and 22, as well as leakage of the electrolyte, can be suppressed. In addition, by providing backflow prevention sections 60 and 70 in the straight flow paths 33 and 43, the backflow prevention section 60 can be formed while keeping the fluid resistance during electrolyte flow low.

[0102] The above embodiment can also be considered an invention of a cell stack comprising a cell frame 1 consisting of an electrode arrangement section 105 on which positive and negative electrodes 101 are arranged and a frame 5 provided around the electrode arrangement section 105, and a plurality of battery cells having a diaphragm 103, wherein the frame 5 of the cell frame 1 has flow paths 31, 32, 41, 42 through which the electrolyte flows, connecting manifolds 11, 12, 21, 22 formed penetrating its four corners to the electrode arrangement section 105, and the flow paths 31, 32, 41, 42 widen from the manifold 11, 12, 21, 22 side of the frame toward the width of the inner circumference on which the electrode arrangement section 105 is provided, and backflow prevention sections 60, 70 are provided along the way to prevent backflow of the electrolyte.

[0103] According to the cell stack of the above embodiment, in the cell frame 1 that constitutes it, groove-shaped flow paths 31, 32, 41, 42 are formed in a frame 5 provided around the electrode arrangement section 105 and communicate between the manifolds 11, 12, 21, 22 and the electrode arrangement section 105, allowing the electrolyte to flow. These flow paths are widened from the manifolds 11, 12, 21, 22 toward the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. In this way, the flow paths 31, 32, 41, and 42 that circulate the electrolyte between the manifolds 11, 12, 21, and 22 and the electrode arrangement section 105 are widened from the manifold 11, 12, 21, and 22 side to match the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. As a result, the width of the flow paths 31, 32, 41, and 42 is larger in diameter than the manifolds 11, 12, 21, and 22, and the flow path length is also shorter. This reduces the fluid resistance of the electrolyte circulating through them, making it possible to reduce the pressure loss of the electrolyte supplied to the cell frame 1. Furthermore, by providing backflow prevention sections 60 and 70 in the middle of the flow paths 31, 32, 41, and 42 to prevent backflow of the electrolyte, current loss (shunt current loss) through the electrolyte can be reduced. Therefore, it is possible to reduce both the pressure loss of the circulating electrolyte and the shunt current loss. This enables higher output in redox flow batteries.

[0104] Furthermore, the above embodiment can also be considered as an invention of a redox flow battery having a cell stack formed by stacking a plurality of battery cells having a cell frame 1 consisting of an electrode arrangement section 105 on which positive and negative electrodes 101 are arranged and a frame 5 provided around the electrode arrangement section 105, and a diaphragm 103, wherein the frame 5 of the cell frame 1 has flow paths 31, 32, 41, 42 through which the electrolyte flows, connecting manifolds 11, 12, 21, 22 formed penetrating its four corners to the electrode arrangement section 105, and the flow paths 31, 32, 41, 42 widen from the manifold 11, 12, 21, 22 side of the frame toward the width of the inner circumference on which the electrode arrangement section 105 is provided, and backflow prevention sections 60, 70 are provided along the way to prevent backflow of the electrolyte.

[0105] In the redox flow battery of the above embodiment, in the cell frame 1 of the cell stack that constitutes it, groove-shaped flow channels 31, 32, 41, 42 are formed in a frame 5 provided around the electrode arrangement section 105 and communicate between the manifolds 11, 12, 21, 22 and the electrode arrangement section 105, allowing the electrolyte to flow. These channels are widened from the manifolds 11, 12, 21, 22 toward the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. In this way, the flow paths 31, 32, 41, and 42 that circulate the electrolyte between the manifolds 11, 12, 21, and 22 and the electrode arrangement section 105 are widened from the manifold 11, 12, 21, and 22 side to match the width of the inner circumference of the frame 5 surrounding the electrode arrangement section 105. As a result, the width of the flow paths 31, 32, 41, and 42 is larger in diameter than the manifolds 11, 12, 21, and 22, and the flow path length is also shorter. This reduces the fluid resistance of the electrolyte circulating through them, making it possible to reduce the pressure loss of the electrolyte supplied to the cell frame 1. Furthermore, by providing backflow prevention sections 60 and 70 in the middle of the flow paths 31, 32, 41, and 42 to prevent backflow of the electrolyte, current loss (shunt current loss) through the electrolyte can be reduced. Therefore, it is possible to reduce both the pressure loss of the circulating electrolyte and the shunt current loss. This enables higher output in redox flow batteries.

[0106] By the way, when implementing the present invention, the configuration of the backflow prevention units 60 and 70 is not limited to the above embodiment as long as it prevents backflow of the electrolyte. Valves or check valves may be provided in the grooves of the flow paths 31, 32, 41, and 42, or steps, grooves, inclines, etc., may be provided in the flow paths. For example, backflow of the electrolyte can be prevented by providing an inclined section (stepped section) that slopes upward from one end on the upstream side through which the electrolyte flows to the other end on the downstream side. In this case, it can be formed inexpensively with a simple configuration that changes the thickness of the frame 5.

[0107] Furthermore, in the above embodiment, the inlet channels 31, 32 and the discharge channels 41, 42 have a substantially concave cross-section. However, the channel walls and groove bottoms forming them are not limited to being planar (straight), but may be curved, and opposing channel walls may be parallel, or tapered. The corners between the channel walls and the groove bottoms are not limited to being substantially right angles, but may be formed in a rounded (R) shape.

[0108] In the above embodiment, the battery cells were described as being connected to each other so that the electrolyte flows through each cell in parallel. However, when implementing the present invention, the connection configuration of the multiple electrical cells is not limited to this, and for example, they may be connected to each other so that the electrolyte flows through the multiple battery cells in series. Furthermore, although the cell stack of the present invention was described in the above explanation using an example of application to a redox flow battery, the present invention is not limited to redox flow batteries and can be applied to other storage batteries and fuel cells.

[0109] Furthermore, when implementing the present invention, the configuration, materials, manufacturing process, etc., of the cell frame 1, cell stack, and other parts of the redox flow battery are not limited to those described in the above embodiments. Also, the numerical values ​​given in the above embodiments are appropriate values ​​suitable for implementation, and slightly changing these values ​​does not negate implementation. [Explanation of Symbols]

[0110] 1 cell frame 5 Frame 11. Manifold for supplying fluid to the positive electrode 12. Manifold for negative electrode fluid supply 13. Manifold for draining the positive electrode side 14. Manifold for draining the negative electrode 31 Positive electrode side introduction channel 32 Negative electrode side introduction channel 33 Inlet straight channel 34. Wide channel for introduction 41 Positive electrode side discharge channel 42 Negative electrode side discharge channel 43. Straight discharge channel 44 Wide discharge channel 60 Inlet side backflow prevention section 66,76 Deep groove (dead end) 67,77 aperture 65,75 Standing piece 65a,75a Base end 65b,75b Free end 70 Discharge side backflow prevention section 101 Electrode 103 Diaphragm 105 Electrode arrangement section 151 Rib

Claims

1. An electrode placement section where electrodes are arranged, A frame is provided with a manifold formed around the electrode arrangement section, through which the electrolyte flows, and through which the front and back surfaces are penetrated. A flow path is formed in the frame, connecting the electrode arrangement section and the manifold, and widening from the manifold side toward the inner circumference of the frame surrounding the electrode arrangement section, through which the electrolyte flows. A backflow prevention unit is provided in the middle of the flow path to prevent the backflow of the electrolyte. It is equipped with, The cell frame is characterized in that the flow path comprises a straight flow path extending from the manifold parallel to the width direction of the electrode arrangement portion provided on the inner circumference of the frame, and a wide flow path that widens from the straight flow path toward the width of the inner circumference of the frame.

2. The cell frame according to claim 1, characterized in that the flow path has a groove bottom that rises from the lower side of the frame parallel to the width direction of the inner circumference of the frame toward the electrode arrangement portion.

3. The cell frame according to claim 1, characterized in that the flow path is provided with a rib on the side connected to the manifold.

4. The cell frame according to claim 1, characterized in that the backflow prevention portion is formed by creating an upright piece cut out from the surface of the frame, and opening the free end side of the upright piece opposite to the base end on the side connected to the frame, thereby forming a dead end below the upright piece.

5. A cell stack comprising a cell frame and a diaphragm, each having a cell frame and a diaphragm, wherein the cell frame is formed by stacking multiple cell cells, each having an electrode arrangement portion where electrodes are arranged and a manifold formed around the electrode arrangement portion, penetrating both the front and back surfaces and through which the electrolyte flows. The aforementioned cell frame is A flow path is formed in the frame, connecting the electrode arrangement section and the manifold, and widening from the manifold side toward the inner circumference of the frame surrounding the electrode arrangement section, through which the electrolyte flows. A backflow prevention unit is provided in the middle of the flow path to prevent the backflow of the electrolyte. It is equipped with, The cell stack is characterized in that the flow path comprises a straight flow path extending from the manifold parallel to the width direction of the electrode arrangement section provided on the inner circumference of the frame, and a wide flow path that widens from the straight flow path toward the width of the inner circumference of the frame.

6. A redox flow battery having a cell stack formed by stacking multiple battery cells, each having a cell frame consisting of an electrode arrangement portion where electrodes are arranged and a manifold formed around the electrode arrangement portion, through which the front and back surfaces are penetrated and through which the electrolyte flows, and a diaphragm, The aforementioned cell frame is A flow path is formed in the frame, connecting the electrode arrangement section and the manifold, and widening from the manifold side toward the inner circumference of the frame surrounding the electrode arrangement section, through which the electrolyte flows. A backflow prevention unit is provided in the middle of the flow path to prevent the backflow of the electrolyte. It is equipped with, The redox flow battery is characterized in that the flow path comprises a straight flow path extending from the manifold parallel to the width direction of the electrode arrangement portion provided on the inner circumference of the frame, and a wide flow path that widens from the straight flow path toward the width of the inner circumference of the frame.

Images