Flow battery unit and flow battery stack

Abstract

The invention relates to the field of redox flow batteries, and provides a redox flow battery unit and a redox flow battery pile, an electrode frame of the redox flow battery unit is provided with a redox flow hole penetrating along the thickness direction and a cover plate mounting groove with a notch facing one side of the thickness direction, and the cover plate mounting groove is provided with an opening communicated with a central area of the electrode frame; the bottom of the cover plate mounting groove is provided with a liquid flow groove for communicating the corresponding liquid flow hole in the electrode frame with the central area of the electrode frame, the electrode frame cover plate is adaptively mounted in the cover plate mounting groove and covers the corresponding liquid flow groove, and the electrode frame cover plate and the corresponding liquid flow groove define an electrolyte flow channel for electrolyte to enter the central area of the electrode frame from the liquid flow hole in the electrode frame; the electrode frame cover plate is embedded into the electrode frame, so that the thickness of the flow battery unit is reduced, the overall thickness of the flow battery stack formed by a plurality of flow battery units is reduced, and the problems of large overall volume and large occupied space of the flow battery stack caused by the large thickness of the flow battery unit in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the field of flow batteries, and particularly to a flow battery unit and a flow battery stack. Background Art

[0002] A flow battery is a chemical energy storage device. Its principle is to use a proton exchange membrane to separate the positive and negative electrolyte solutions. The negative electrolyte solution undergoes an oxidation reaction to lose electrons, and the positive electrolyte solution undergoes a reduction reaction to gain electrons, so as to form a voltage between the positive and negative electrodes to supply power outward; during charging, the positive and negative electrolyte solutions undergo reverse reactions; the flow battery has the characteristics of high capacitance, recyclability, and high safety.

[0003] In the prior art, the common flow battery is usually in the form of a flow battery stack formed by connecting multiple flow battery units in series. The flow battery unit includes an electrode frame, electrode plates installed in the electrode frame, and a bipolar plate for electrically connecting the positive and negative electrodes. A flow channel for introducing the electrolyte solution to the electrode plates is provided on the electrode frame. The flow channel is integrally formed with the electrode frame. Electrode frames are installed on both side surfaces of the bipolar plate to install the positive and negative electrode plates. Multiple flow battery units are arranged in a stacked manner in sequence. Adjacent flow battery units are separated by a proton exchange membrane, and power is supplied outward by introducing the electrolyte solution into the electrode frame.

[0004] However, setting a flow channel integrally formed with the electrode frame on the electrode frame has a high cost and a complex manufacturing process. To simplify the flow channel forming process, a Chinese invention patent with the authorization announcement number CN112264708B provides a flow battery unit. A flow channel groove is opened on the electrode frame, and a layer of cover plate frame is provided between the electrode frame and the bipolar plate. The cover plate frame is adapted to the shape of the electrode frame and covers the flow channel groove. The cover plate frame is fixed and sealed with the electrode frame. The flow channel groove and the cover plate frame form a flow channel for the electrolyte solution to flow through, which simplifies the flow channel forming process and saves the flow channel forming cost.

[0005] However, the problem of this solution is that adding a layer of cover plate frame between the positive and negative electrode frames and the bipolar plate will increase the thickness of the flow battery unit, making the volume of the flow battery unit larger. When multiple flow battery units are connected in series to form a flow battery stack, the overall volume of the flow battery increases, occupying a larger space compared to the structure where the flow channel is integrally formed with the electrode frame. Summary of the Invention

[0006] The purpose of the present invention is to provide a flow battery unit and a flow battery stack to solve the problem that the structure of surrounding the flow channel by the cover plate frame and the flow channel groove in the existing flow battery unit results in a large thickness, leading to a large volume of the flow battery stack; the purpose of the present invention is also to provide a flow battery stack to solve the above technical problems.

[0007] To achieve the above object, the present invention provides a flow battery cell, comprising an electrode frame and a frame cover plate. The electrode frame is provided with liquid flow holes penetrating along its thickness direction and cover plate mounting grooves with openings facing one side in the thickness direction of the electrode frame. The cover plate mounting grooves have inner openings communicating with the central region of the electrode frame. The bottom of the cover plate mounting grooves is provided with electrolyte flow channel grooves for communicating the corresponding liquid flow holes on the electrode frame with the central region of the electrode frame. The frame cover plate is adaptively mounted in the cover plate mounting grooves and covers the corresponding electrolyte flow channel grooves. The frame cover plate and the corresponding electrolyte flow channel grooves form an electrolyte flow channel for the electrolyte to enter the central region of the electrode frame from the liquid flow holes on the electrode frame.

[0008] Further, at least two liquid flow holes for the same-pole electrolyte to flow through are provided on the same electrode frame. A cover plate mounting groove is provided at each liquid flow hole communicating with an electrolyte flow channel, and the above-mentioned frame cover plates are respectively mounted in the cover plate mounting grooves.

[0009] Further, the contour shape of the projection of the cover plate mounting groove in the thickness direction of the electrode frame is the same as the contour shape of the projection of the corresponding electrolyte flow channel groove in the thickness direction of the electrode frame.

[0010] Further, the liquid flow holes on the electrode frame communicating with the electrolyte flow channels are provided at the bottom of the corresponding cover plate mounting grooves. The frame cover plate is provided with cover plate liquid flow holes, and the cover plate liquid flow holes are arranged corresponding to the liquid flow holes of the electrode frame. A seal is formed between the peripheral edge of the frame cover plate at the position of the cover plate liquid flow hole and the peripheral edge of the corresponding liquid flow hole of the electrode frame.

[0011] Further, a gap is provided between the outer edge of the frame cover plate and the groove wall of the cover plate mounting groove.

[0012] Further, the frame cover plate is also provided with a spot welding area for fixing to the electrode frame and / or the bipolar plate of the flow battery cell by spot welding, and the spot welding area of the frame cover plate is staggered from the part covering the electrolyte flow channel groove.

[0013] Further, the flow battery cell includes a bipolar plate and two of the above-mentioned electrode frames respectively located on both sides of the bipolar plate. An electrode plate is also mounted at the central position of the electrode frame. The two electrode frames are respectively a first electrode frame and a second electrode frame. The liquid flow holes for the same-pole electrolyte to pass through on the first electrode frame and the second electrode frame correspond to each other. An electrolyte flow channel is provided at the liquid flow hole for the positive electrode electrolyte to pass through on one of the first electrode frame and the second electrode frame, and an electrolyte flow channel is provided at the liquid flow hole for the negative electrode electrolyte to pass through on the other. The liquid flow holes on the electrode frame not communicating with the electrolyte flow channels are convex parts. The bipolar plate is provided with avoidance holes for avoiding the convex parts so that the convex parts are abutted against the adjacent frame cover plates.

[0014] Further, the frame cover plate, the bipolar plate and the electrode frame are fixed together by fusion welding.

[0015] Furthermore, the extreme frame cover plate is flush with the surface of the electrode frame, the bipolar plate is flush with the top surface of the convex part, and a circle of edges around the avoidance hole on the bipolar plate is sealed with the two side electrode frames by welding.

[0016] Beneficial effects: The present invention pioneeringly provides a flow battery unit in which an extreme frame cover plate is embedded in an electrode frame. The flow battery unit is provided with a cover plate installation groove on the electrode frame and an electrolyte flow channel groove is opened in the cover plate installation groove. At the same time, an extreme frame cover plate covering the corresponding electrolyte flow channel groove is fixedly covered in the cover plate installation groove. The plate wall of the extreme frame cover plate cooperates with the bottom of the electrolyte flow channel groove to form an electrolyte flow channel; by using the cover plate installation groove, the extreme frame cover plate is embedded in the electrode frame. On the premise that the electrolyte flow channel is designed as a groove to cooperate with the extreme frame cover plate, the overall thickness of the flow battery unit is reduced, and the problem that the structure of the flow battery unit in the prior art, in which the flow channel is surrounded by a cover plate frame and a flow channel groove, results in a large thickness and thus a large volume of the flow battery stack is solved.

[0017] To solve the above technical problems, the present invention provides a flow battery stack, which includes a plurality of flow battery units connected in series. The flow battery unit includes an electrode frame and an extreme frame cover plate. The electrode frame is provided with a liquid flow hole penetrating along its thickness direction and a cover plate installation groove with a notch facing one side in the thickness direction of the electrode frame. The cover plate installation groove has an inner opening communicating with the central area of the electrode frame. The bottom of the cover plate installation groove is provided with an electrolyte flow channel groove connecting the corresponding liquid flow hole on the electrode frame with the central area of the electrode frame. The extreme frame cover plate is adaptively installed in the cover plate installation groove and covers the corresponding electrolyte flow channel groove. The extreme frame cover plate and the corresponding electrolyte flow channel groove enclose an electrolyte flow channel for the electrolyte to enter the central area of the electrode frame from the liquid flow hole on the electrode frame.

[0018] Furthermore, at least two liquid flow holes for the same-pole electrolyte to flow through are provided on the same electrode frame. A cover plate installation groove is provided at each liquid flow hole communicating with the electrolyte flow channel, and the above-mentioned extreme frame cover plate is respectively installed in each cover plate installation groove.

[0019] Furthermore, the contour shape of the projection of the cover plate installation groove in the thickness direction of the electrode frame is the same as the contour shape of the projection of the corresponding electrolyte flow channel groove in the thickness direction of the electrode frame.

[0020] Furthermore, the liquid flow hole on the electrode frame communicating with the electrolyte flow channel is provided at the bottom of the corresponding cover plate installation groove. The extreme frame cover plate is provided with a cover plate liquid flow hole, and the cover plate liquid flow hole is correspondingly arranged with the liquid flow hole of the electrode frame. A seal is formed between a circle of edges of the extreme frame cover plate at the cover plate liquid flow hole and a circle of edges of the corresponding liquid flow hole of the electrode frame.

[0021] Furthermore, a gap is provided between the outer edge of the extreme frame cover plate and the groove wall of the cover plate installation groove.

[0022] Further, the bipolar plate cover is further provided with a spot welding area for fixing to the bipolar plate of the electrode frame and / or the flow battery unit by spot welding, and the spot welding area of the bipolar plate cover is staggered from the part covering the electrolyte flow channel groove.

[0023] Further, the flow battery unit includes a bipolar plate and two of the above-mentioned electrode frames respectively located on both sides of the bipolar plate. An electrode plate is further installed at the central position of the electrode frame. The two electrode frames are respectively a first electrode frame and a second electrode frame. The liquid flow holes for the same-pole electrolyte to pass through in the first electrode frame and the second electrode frame correspond to each other. An electrolyte flow channel is provided at the liquid flow hole for the positive electrolyte to pass through on one of the first electrode frame and the second electrode frame, and an electrolyte flow channel is provided at the liquid flow hole for the negative electrolyte to pass through on the other. The liquid flow hole of the electrode frame not connected to the electrolyte flow channel is a convex part, and the bipolar plate is provided with an avoidance hole for avoiding the convex part so that the convex part abuts against the adjacent bipolar plate cover.

[0024] Further, the bipolar plate cover, the bipolar plate and the electrode frame are fixed together by fusion welding.

[0025] Further, the surface of the bipolar plate cover is flush with the surface of the electrode frame, the top surface of the bipolar plate is flush with the top surface of the convex part, and a circle of edges around the avoidance hole on the bipolar plate is sealed with the two-side electrode frames by welding.

[0026] Beneficial effects: The present invention changes the structure of the flow battery unit in the flow battery stack of the prior art, and provides a flow battery stack including a plurality of serially connected flow battery units. The flow battery unit is provided with a cover plate installation groove on the electrode frame and the electrolyte flow channel groove is opened in the cover plate installation groove. At the same time, a bipolar plate cover covering the corresponding electrolyte flow channel groove is also fixed in the cover plate installation groove. The plate wall of the bipolar plate cover cooperates with the bottom of the electrolyte flow channel groove to form an electrolyte flow channel; since the bipolar plate cover is embedded in the electrode frame, on the premise of designing the electrolyte flow channel as a groove to cooperate with the bipolar plate cover, the overall thickness of the flow battery unit is reduced. When the flow battery units are serially connected to form an integrated flow battery stack, the overall volume of the flow battery stack is reduced, and the problem that the large thickness of the flow battery unit in the prior art due to the structure of enclosing the flow channel by the cover plate frame and the flow channel groove leads to a large volume of the flow battery stack is solved. Description of the drawings

[0027] Figure 1 is a top view of the flow battery unit of the present invention; Figure 2 is Figure 1 a cross-sectional view taken along line E-E in Figure 3 is Figure 2 an enlarged structural schematic diagram at position A in Figure 4 is Figure 2 The enlarged structural schematic diagram at position B in

[0028] In the figure: 1. Electrode frame; 11. First electrode frame; 12. Second electrode frame; 2. Bipolar plate; 3. Peripheral sealing area; 4. Electrode frame cover plate; 41. First electrode frame cover plate; 42. Second electrode frame cover plate; 5. Spot welding area; 6. First liquid flow hole; 7. Liquid flow hole sealing area; 8. Electrode plate; 81. First electrode plate; 82. Second electrode plate; 9. Second liquid flow hole; 91. Electrolyte channel. Specific embodiments

[0029] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0030] The principle and concept of the present invention are as follows: A groove for installing an electrode frame cover plate is provided on the electrode frame provided with an electrolyte flow channel groove in the flow battery unit, the electrolyte flow channel groove is arranged in the groove and the electrode frame cover plate is used to cover the electrolyte flow channel groove to form a flow channel for the electrolyte to flow through. The electrode frame cover plate embedded in the electrode frame in this way limits the overall thickness of the electrode frame and the electrode frame cover plate to be the same as the thickness of the electrode frame, reducing the overall thickness of the flow battery unit, and further reducing the overall volume of the flow battery stack composed of multiple flow battery units.

[0031] Based on the above principle, the present invention provides a flow battery unit and various embodiments thereof.

[0032] On the basis of the above principle and concept, in a basic embodiment, as Figures 1-4 In the provided embodiment, the flow battery unit includes a bipolar plate 2 and two electrode frames 1 fixed on both sides of the bipolar plate 2. The electrode frame 1 has an inner side surface that fits and cooperates with the bipolar plate 2. The electrode frame 1 is also provided with a liquid flow hole that penetrates along its thickness direction and a cover plate installation groove with a notch facing one side in the thickness direction of the electrode frame 1. The cover plate installation groove has an inner opening communicating with the central area of the electrode frame. An electrolyte flow channel groove for the electrolyte to flow through is opened at the bottom of the cover plate installation groove. The electrolyte flow channel groove extends from the liquid flow hole to the central area of the electrode frame 1. A pole frame cover plate 4 covering the electrolyte flow channel groove is also fitted and installed in the cover plate installation groove. The pole frame cover plate is installed in the cover plate installation groove so that the area of the pole frame cover plate 4 is smaller than the frame edge area of the electrode frame. The pole frame cover plate 4 and the electrolyte flow channel groove cooperate to form an electrolyte flow channel for the electrolyte to enter the central area of the electrode frame from the liquid flow hole on the electrode frame.

[0033] In this way, the extreme frame cover plate 4 is fitted on one side in the thickness direction of the electrode frame 1. The cover plate installation groove provides a positioning reference for the installation of the extreme frame cover plate 4. More importantly, the embedded extreme frame cover plate 4 reduces the thickness of the flow battery unit. Furthermore, when multiple flow battery units need to be connected in series to form a large-capacity flow battery stack, the spatial size of the flow battery stack is reduced, solving the problem in the prior art that the structure of the flow battery unit with the flow channel surrounded by the cover plate frame and the flow channel groove results in a larger thickness and thus a larger volume of the flow battery stack.

[0034] It should be noted that in this article, taking Figure 2 the bipolar plate 2 of the flow battery unit as the center line, the electrode frame on the left side of the bipolar plate 2 will be referred to as the first electrode frame 11 hereinafter, and the one on the right side is the second electrode frame 12. Similarly, according to the left and right orientations of the bipolar plate, the extreme frame cover plate 4 is divided into the first extreme frame cover plate 41 and the second extreme frame cover plate 42, and the electrode plate 8 is divided into the first electrode plate 81 and the second electrode plate 82. The electrode plate 8 is located in the central area of the above-mentioned electrode frame 1 and is fixedly attached to the bipolar plate 2.

[0035] The main body of the flow battery unit is a laminated structure. Taking the bipolar plate 2 as the center, the first electrode frame 11 and the second electrode frame 12 are respectively fixed on both sides of the bipolar plate 2. The two side surfaces of the bipolar plate 2 are attached and fixed to the inner side surfaces of the electrode frame 1. The electrode frame 1 has a central area, and an electrode plate 8 is arranged in the central area of the electrode frame 1. The outer contour of the electrode plate 8 is adapted to the central area of the electrode frame 1 and is fixedly attached to the bipolar plate; when multiple flow battery units are connected in series to form a flow battery stack, a proton exchange membrane is arranged between adjacent flow battery units, and the relatively facing electrode frames of the two flow battery units are fixedly attached to complete the series connection of the two flow battery units.

[0036] The flow holes of the flow battery unit can be divided into positive electrode flow holes and negative electrode flow holes according to the polarity of the flowing electrolyte. The electrode frame can be divided into a positive electrode frame and a negative electrode frame according to the electrolyte flowing into the central area. The flow holes arranged on the same electrode frame are arranged at intervals according to the positive and negative polarities. According to the polarity of the electrolyte flowing in the flow holes, electrolyte flow channels are arranged on the pore walls of the flow holes on the electrode frame corresponding to the polarity, in order to Figure 2 take as an example, define the left side of the bipolar plate 2 as the positive electrode reaction area and the right side as the negative electrode reaction area. The positive electrode electrolyte flows into the second flow hole 9, so electrolyte flow channel grooves are only opened on the flow holes of the first electrode frame 11 in the positive electrode reaction area and covered with the extreme frame cover plate 4.

[0037] The electrolyte flow channel groove starts from the flow hole and extends along the frame edge direction of the electrode frame 1, and the flow channel is relatively narrow here. After extending a certain length, it turns into the central area of the electrode frame 1 and the notch increases. Therefore, in Figure 2The cross-section of the notch enlargement area of the electrolyte flow channels corresponding to the left and right sides shown at position B in the figure is shown, and due to the different liquid flow holes for the positive and negative electrode electrolytes to flow through, in Figure 2 only the electrolyte flow channel 91 on the liquid flow hole of the electrode frame 11 is shown in the cross-sectional view shown. It should be understood that the structure at the negative electrode liquid flow hole is the same as that Figure 2 shown at the liquid flow hole.

[0038] Based on the above embodiments, in one embodiment, as Figures 1-4 provided in the embodiment, at least two liquid flow holes for the same-pole electrolyte to flow through are provided on the same electrode frame 1, and a cover plate mounting groove is provided at each liquid flow hole connected to the electrolyte flow channel. A pole frame cover plate 4 is independently provided in each cover plate mounting groove. In this way, the pole frame cover plate is set as a multi-piece structure, reducing the area occupied by the cover plate mounting groove on the inner side of the electrode frame 1 and improving the structural strength of the electrode frame 1; in another embodiment, a square groove can also be provided along the extending direction of the frame edge on the frame edge of the electrode frame provided with the liquid flow hole, and all the liquid flow holes on the same side frame edge and the electrolyte flow channel grooves corresponding to the liquid flow holes are arranged in the same square groove.

[0039] Based on the above embodiments, in one embodiment, as Figures 1-4 provided in the embodiment, the projection of the cover plate mounting groove of the electrode frame 1 in the thickness direction of the electrode frame 1 is adapted to the outer contour shape of the electrolyte flow channel groove. Similarly, the projection of the pole frame cover plate 4 in the thickness direction of the electrode frame 1 is adapted to the shape of the electrolyte flow channel groove, that is, the pole frame cover plate only needs to just cover the electrolyte flow channel groove, and the area of the pole frame cover plate 4 can be minimized as much as possible to reduce material loss; making the projection contour of the cover plate mounting groove as adapted to the outer contour shape of the electrolyte flow channel groove as possible reduces the area of the groove opened on the electrode frame 1 and enhances the structural strength of the electrode frame 1; in another embodiment, the groove can also be set as a square groove along the direction of the electrode frame border, and the pole frame cover plate is set as a square plate adapted to the square groove and covering the electrolyte flow channel groove. The square plate-shaped pole frame cover plate has a simple structure and is convenient to manufacture.

[0040] Based on the above embodiments, in one embodiment, as Figures 1-4In the provided embodiments, the liquid flow holes on the electrode frame 1 are provided at the bottom of the cover plate installation groove. There are also cover plate liquid flow holes on the electrode frame cover plate 4, and the positions of the cover plate liquid flow holes correspond to those of the liquid flow holes on the electrode frame 1. By fixing the electrode frame cover plate 4 in the cover plate installation groove, the plate wall forming the cover plate liquid flow hole seals the area around the liquid flow hole, preventing the electrolyte in the liquid flow hole from flowing into the reaction area of the opposite electrode through the joint seam between the electrode frame cover plate 4 and the electrode frame 1. In another embodiment, the liquid flow hole can be opened on one side of the cover plate installation groove and connected to the side wall of the cover plate installation groove to communicate the cover plate installation groove with the liquid flow hole. The electrode frame cover plate does not cover the liquid flow hole at this position, and the liquid flow hole is sealed in a circle after being attached to the electrode frame or the bipolar plate.

[0041] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiments, there is a gap between the groove wall of the cover plate installation groove and the side edge of the electrode frame cover plate 4. In this way, before fixing the electrode frame cover plate 4 to the electrode frame 1, there is a certain adjustment space when aligning the electrode frame cover plate 4 with the electrode frame 1. At the same time, to a certain extent, the dimensional requirements for the external contour of the electrode frame cover plate 4, which imitates the external contour of the electrolyte flow groove, are reduced, improving the production efficiency.

[0042] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiments, the flow battery unit includes a bipolar plate 2 and a first electrode frame 11 and a second electrode frame 12 installed on the left and right sides of the bipolar plate 2. It also includes a first electrode plate 81 and a second electrode plate 82 respectively installed inside the two electrode frames. The liquid flow holes for the electrolyte of the same pole to flow through on the first electrode frame 11 and the second electrode frame 12 are correspondingly arranged; an electrolyte flow channel groove for guiding the electrolyte to the electrode plate is provided at the liquid flow hole where the positive electrolyte flows through on one of the first electrode frame 11 and the second electrode frame 12, and an electrolyte flow channel groove for guiding the electrolyte to the electrode plate is provided at the liquid flow hole where the negative electrolyte flows through on the other one. A convex portion is provided at the liquid flow hole on the electrode frame 1 where no flow channel groove is connected. A relief hole for avoiding the convex portion is opened on the bipolar plate 2, so that the convex portion on one electrode frame abuts against the electrode frame cover plate on the other electrode frame. In this way, the bipolar plate 2 is arranged in a form embedded in the electrode frame, further reducing the thickness of the flow battery unit.

[0043] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiments, the electrode frame cover plate 4 is welded and fixed in the cover plate installation groove on the electrode frame 1. Taking Figure 2 as an example, after welding the electrode frame cover plate 4 and the electrode frame 1, the weld seam around the liquid flow hole can play a good sealing role, preventing the remaining positive electrolyte at the liquid flow hole from flowing into the second electrode plate 82 along the joint seam between the electrode frame cover plate 4 and the electrode frame 12.

[0044] The bipolar plate 2 and the electrode frames 1 on both sides are fixed by welding. Welding areas surrounding the convex portion are provided on the mating surfaces of the bipolar plate 2 and the electrode frames 1 on both sides. The internal seams of the flow battery unit are sealed by the welding here, preventing the electrolyte inside the electrode frame 1 from flowing upward along the seam between the first electrode frame 11 and the bipolar plate 2 and flowing into the central area of the second electrode frame 12 from the mating area between the convex portion of the second electrode frame 12 and the cover plate mounting groove of the first electrode frame 11.

[0045] It should be noted that the present invention preferably uses fusion welding to fix and seal the pole frame cover plate 4 to the electrode frame 1, and the bipolar plate 2 to the electrode frame 1. After the components are mated, they are fixed together by fusion welding. In other embodiments, laser welding or sealant gluing can also be used for sealing.

[0046] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiment, a liquid flow hole sealing area 7 is provided around the first liquid flow hole 6 and the second liquid flow hole 9 on the electrode frame 1. In this embodiment, the liquid flow hole sealing area 7 is preferably set as an annular shape and a hot melt welding area is provided in the annular liquid flow hole sealing area 7, and sealing is achieved through hot melt welding; in other embodiments, sealing gaskets or laser welding can also be used for welding.

[0047] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiment, a spot welding area 5 is further provided on the mating surface of the bipolar plate 2 and the pole frame cover plate 4 to reinforce the connection between the bipolar plate 2 and the pole frame cover plate 4, avoiding warping of the bipolar plate 2 due to the heat generated by the welding process or external pressure during the assembly of the flow battery unit. In another embodiment, the bipolar plate can also be bonded to the electrode frame with structural adhesive before welding the bipolar plate to the electrode frame, and warping deformation of the bipolar plate during fusion welding is avoided through the structural adhesive.

[0048] Based on the above embodiments, in one embodiment, as Figures 1-4 In the provided embodiment, the area of the bipolar plate 2 is smaller than the outer contour of the electrode frame 1. A welding area is provided along the outer contour of the bipolar plate 2 at a position close to the edge of the bipolar plate 2 on the mating surface of the bipolar plate 2 and the electrode frame 1. The welding area is arranged along the outer edge of the electrode frame to prevent the electrolyte from penetrating to the outer edge of the bipolar plate 2, achieving the outer edge welding seal of the flow battery unit.

[0049] Embodiment of the flow battery stack of the present invention: The present invention also provides a flow battery stack. The flow battery stack includes a plurality of flow battery units stacked and connected together. A proton exchange membrane is provided between two adjacent flow battery units. The structure of the flow battery unit is the same as that of any one of the flow battery units introduced in the above embodiments, and will not be elaborated here too much.

[0050] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. The scope of patent protection of the present invention is subject to the claims. Any equivalent structural changes made by using the content of the specification and drawings of the present invention should be equally included in the protection scope of the present invention.

Claims

1. A flow battery cell, characterized in that, It includes an electrode frame and a frame cover plate. The electrode frame is provided with liquid flow holes penetrating along its thickness direction and cover plate mounting grooves with the notch facing one side in the thickness direction. The cover plate mounting grooves have inner openings communicating with the central area of the electrode frame. The bottom of the cover plate mounting grooves is provided with electrolyte flow channel grooves that connect the corresponding liquid flow holes on the electrode frame with the central area of the electrode frame. The frame cover plate is adaptively mounted in the cover plate mounting grooves and covers the corresponding electrolyte flow channel grooves. The frame cover plate and the corresponding electrolyte flow channel grooves form an electrolyte flow channel for the electrolyte to enter the central area of the electrode frame from the liquid flow holes on the electrode frame.

2. The flow battery cell according to claim 1, characterized in that, On the same electrode frame, at least two liquid flow holes for the same-pole electrolyte to flow through are provided. A cover plate mounting groove is provided at each liquid flow hole connected to the electrolyte flow channel, and the above-mentioned frame cover plate is respectively mounted in each cover plate mounting groove.

3. The flow battery cell according to claim 2, characterized in that, The contour shape of the projection of the cover plate mounting groove in the thickness direction of the electrode frame is the same as the contour shape of the projection of the corresponding electrolyte flow channel groove in the thickness direction of the electrode frame.

4. The flow battery cell according to any one of claims 1-3, characterized in that, The liquid flow holes on the electrode frame communicating with the electrolyte flow channel are arranged at the bottom of the corresponding cover plate mounting grooves. The frame cover plate is provided with cover plate liquid flow holes, and the cover plate liquid flow holes are arranged corresponding to the liquid flow holes on the electrode frame. A seal is formed between the peripheral edge of the frame cover plate at the cover plate liquid flow holes and the peripheral edge of the corresponding liquid flow holes on the electrode frame.

5. The flow battery cell according to any one of claims 1-3, characterized in that, A gap is provided between the outer edge of the frame cover plate and the groove wall of the cover plate mounting groove.

6. The flow battery cell according to any one of claims 1-3, characterized in that, The frame cover plate is further provided with a spot welding area for being fixed to the electrode frame and / or the bipolar plate of the flow battery unit by spot welding. The spot welding area of the frame cover plate is staggered from the part covering the electrolyte flow channel groove.

7. The flow battery unit according to any one of claims 1 to 3, characterized in that, The flow battery unit includes a bipolar plate and two of the above-mentioned electrode frames respectively located on both sides of the bipolar plate. An electrode plate is further mounted at the central position of the electrode frame. The two electrode frames are respectively a first electrode frame and a second electrode frame. The liquid flow holes for the same-pole electrolyte to pass through on the first electrode frame and the second electrode frame correspond. An electrolyte flow channel is provided at the liquid flow hole for the positive electrolyte to pass through on one of the first electrode frame and the second electrode frame, and an electrolyte flow channel is provided at the liquid flow hole for the negative electrolyte to pass through on the other. The liquid flow holes on the electrode frame not connected to the electrolyte flow channel are convex parts. The bipolar plate is provided with avoidance holes for avoiding the convex parts so that the convex parts abut against the adjacent frame cover plates.

8. The flow battery cell according to claim 7, characterized in that, The frame cover plate, the bipolar plate and the electrode frame are fixed together by fusion welding.

9. The flow battery cell according to claim 7, characterized in that, The frame cover plate is flush with the surface of the electrode frame, the bipolar plate is flush with the top surface of the convex part, and a seal is formed by welding between the peripheral edge of the bipolar plate surrounding the avoidance hole and the electrode frames on both sides.

10. A flow battery stack, characterized in that, It includes a plurality of flow battery units connected in series, and the flow battery unit is the flow battery unit according to any one of claims 1-9.

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