Electrode frame and bipolar plate of flow battery
By optimizing the flow field structure of the electrode frame and bipolar plate of the liquid flow battery, the problems of uneven distribution and poor diffusion effect of the electrolyte are solved, and the uniform distribution of the electrolyte in the electrode area and the improvement of the mass transfer effect are achieved, and the performance and assembly convenience of the battery are improved.
Patent Information
- Application Number
- CN202422460618.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2034-10-12
AI Technical Summary
The flow field structure design of existing flow batteries has problems such as uneven distribution of electrolyte, poor concentration polarization and diffusion effect, which affects battery performance.
A liquid flow battery electrode frame and bipolar plate are designed, using liquid inlet and outlet comb-type flow paths, flow homogenization flow paths and support structures, combined with the expansion and shrinkage structure of the bipolar plate flow paths, optimize the flow field design to enhance the uniform distribution and mass transfer effect of the electrolyte.
The permeability and mass transfer effect of the electrolyte in the electrode area are improved, the internal resistance of concentration difference is reduced, and the power density and assembly convenience of the stack are enhanced.
Smart Images
Figure CN223309009U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of liquid flow batteries, and in particular to a liquid flow battery electrode frame and a bipolar plate with a flow balancing effect. Background Art
[0002] Among numerous energy storage technologies, flow batteries have become a preferred choice for large-scale energy storage systems due to their advantages, including power and capacity decoupling, high reliability, excellent safety, and long life. Unlike lithium-ion batteries, the electrolyte in flow batteries continuously circulates, primarily transferring mass through convection rather than diffusion. Therefore, optimizing the flow field structure to improve the flow properties of the electrolyte within the flow field and fully exploit the mass transfer advantages of flow batteries is an effective strategy for reducing battery polarization and increasing the power density of the stack.
[0003] A single cell in a flow battery primarily consists of an ion-conducting membrane, porous electrodes, an electrode frame, bipolar plates, and end plates. The flow and mass transfer region within a flow battery is primarily within the electrode reaction zone, requiring design of the flow field structures within both the electrode frame and the bipolar plates. Designing the flow field structure within the electrode frame ensures uniform flow distribution at the inlet of the electrode reaction zone. Designing the flow field structure within the bipolar plates effectively reduces the pressure drop across the electrode reaction zone, but this also affects electrolyte diffusion within the electrode region, leading to concentration polarization. Common bipolar plate flow field structures currently available include serpentine channels, parallel channels, and interdigitated channels, but each has limitations. In serpentine channels, the pressure differential increases with channel length, leading to uneven electrolyte distribution. Parallel channels extend throughout the entire electrode reaction zone, making it difficult for the electrolyte to fully penetrate the electrodes, potentially leading to concentration polarization. Similar to parallel channels, interdigitated channels tend to flow vertically, resulting in poor horizontal diffusion along the electrodes. Utility Model Content
[0004] In order to solve the above-mentioned technical problems, the present application provides a liquid flow battery electrode frame and bipolar plate, including an electrode frame, on which are provided a liquid inlet main channel, a liquid inlet connecting channel, a liquid inlet uniform flow channel, a liquid inlet comb-type channel, a liquid outlet main channel, a liquid outlet connecting channel, a liquid outlet uniform flow channel, and a liquid outlet comb-type channel; supports are provided in the liquid inlet connecting channel and the liquid outlet connecting channel, and the supports divide the liquid inlet connecting channel and the liquid outlet connecting channel into multiple flow areas; the liquid inlet uniform flow channel and the liquid outlet uniform flow channel include multiple guide blocks; a plurality of linear arrays of liquid inlet comb-type supports are provided in the liquid inlet comb-type channel, and a plurality of linear arrays of liquid outlet comb-type supports are provided in the liquid outlet comb-type channel; and a bipolar plate covering the electrode frame is also provided, on which a bipolar plate flow channel is provided.
[0005] Optionally, the widths of the plurality of flow areas are equal, and the liquid inlet communication flow channel and the liquid outlet communication flow channel are symmetrical about the center of the electrode frame.
[0006] Optionally, the guide blocks in the inlet and outlet equal flow channels are symmetrically arranged about the axis of the electrode frame perpendicular to the electrolyte flow direction; the several guide blocks in the inlet and outlet equal flow channels are divided into several layers along the electrolyte flow direction, and the spacing between each layer is 3-5mm; along the electrolyte flow direction, the number of guide blocks in each layer gradually increases and the length of the guide blocks gradually decreases; the guide blocks in the inlet and outlet equal flow channels are symmetrically arranged about the axis of the electrode frame parallel to the electrolyte flow direction.
[0007] Optionally, the liquid inlet comb-shaped flow channel and the liquid outlet comb-shaped flow channel are symmetrically arranged; a flow area is formed between two adjacent liquid inlet comb-shaped supports, and the flow area and the projection size of the liquid inlet comb-shaped support on the electrode frame are the same.
[0008] Optionally, a bipolar plate fixing groove is opened on the electrode frame, and a bipolar plate fixing block is provided on the bipolar plate, and the bipolar plate fixing block is inserted into the bipolar plate fixing groove and fixed.
[0009] Optionally, the bipolar plate flow channel extends in the direction of electrolyte flow, and the bipolar plate flow channel is located between the liquid inlet comb-type flow channel and the liquid outlet comb-type flow channel; two adjacent bipolar plate flow channels form a group, and one bipolar plate flow channel in each group is connected to the liquid inlet comb-type flow channel but not to the liquid outlet comb-type flow channel, and the other is connected to the liquid outlet comb-type flow channel but not to the liquid inlet comb-type flow channel.
[0010] Optionally, the distance between the closed end of the bipolar plate flow channel and the liquid inlet comb-shaped flow channel is less than 10% of the width of the bipolar plate, and the distance is greater than the spacing between two adjacent bipolar plate flow channels.
[0011] Optionally, each bipolar plate flow channel is connected to 1-2 flow areas.
[0012] Optionally, the bipolar plate flow channel consists of an expansion area and a contraction area, the expansion area width W1 is equal to the contraction area width W2, the expansion area and the contraction area length are equal and equal to 1 / 4 of the bipolar plate flow channel width L1, and the spacing L2 between two adjacent bipolar plate flow channels is equal to the interdigital flow channel width L1.
[0013] In summary, this application includes at least one of the following beneficial technical effects:
[0014] 1. Adjust the flow rate by changing the flow area before flowing into the electrode reaction area, reduce the flow deviation at the inlet of the electrode reaction area, and enhance flow mass transfer;
[0015] 2. The bipolar plate flow channel adds expansion and contraction structures on the basis of ordinary interdigital flow channels. By periodically changing the cross-section of the interdigital flow channel, the pressure difference caused by the fluid penetrating into the electrode area is increased, the electrolyte flow rate penetrating into the electrode area is increased, and the flow uniformity in the electrode area is enhanced;
[0016] 3. The bipolar plate and electrode frame are fixed together to facilitate stack assembly. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.
[0018] Figure 2 This is a schematic diagram of the local structure of an embodiment of the present application.
[0019] Figure 3 It is a velocity vector diagram of the variable cross-section interdigital flow channel and the traditional interdigital flow channel in the embodiment of the present application.
[0020] Explanation of the accompanying reference numerals: 1. liquid inlet main channel; 2. liquid inlet connecting channel; 3. liquid inlet uniform flow channel; 4. liquid inlet comb-type channel; 401, liquid inlet comb-type support; 5. liquid outlet main channel; 6. liquid outlet connecting channel; 7. liquid outlet uniform flow channel; 8. liquid outlet comb-type channel; 801, liquid outlet comb-type support; 9. support; 10. guide block; 11. bipolar plate; 1101, bipolar plate channel; 1102, bipolar plate fixing block; 12. bipolar plate fixing groove. DETAILED DESCRIPTION
[0021] The following is combined with Figure 1-3 This application is described in further detail.
[0022] The present application discloses a flow battery electrode frame and a bipolar plate. Figure 1 A liquid flow battery electrode frame and bipolar plate include an electrode frame and a bipolar plate 11 covering the electrode frame.
[0023] Reference Figure 1 The electrode frame is in the shape of a rectangular parallelepiped, and a liquid inlet main channel 1, a liquid inlet connecting channel 2 connected to the liquid inlet main channel 1, a liquid inlet uniform flow channel 3 connected to the liquid inlet connecting channel 2, and a liquid inlet comb-shaped flow channel 4 connected to the liquid inlet uniform flow channel 3 are provided at the lower part of the electrode frame.
[0024] Reference Figure 1 The upper part of the electrode frame is provided with a liquid outlet main channel 5, a liquid outlet connecting channel 6 connected to the liquid outlet main channel 5, a liquid outlet uniform flow channel 7 connected to the liquid outlet connecting channel 6, and a liquid outlet comb-shaped flow channel 8 connected to the liquid outlet uniform flow channel 7.
[0025] refer to Figure 1 Two supports 9 are provided in the liquid inlet communicating flow channel 2 and the liquid outlet communicating flow channel 6. The two supports 9 divide the liquid inlet communicating flow channel 2 and the liquid outlet communicating flow channel 6 into three flow areas; the three flow areas have equal widths, and the liquid inlet communicating flow channel 2 and the liquid outlet communicating flow channel 6 are symmetrical about the center of the electrode frame.
[0026] refer to Figure 1The inlet and outlet equalizing flow channel 3 and the outlet equalizing flow channel 7 include multiple guide blocks 10, which are rectangular in shape, and the length direction of the guide blocks 10 is perpendicular to the flow direction of the electrolyte; the guide blocks 10 in the inlet and outlet equalizing flow channel 3 and the outlet equalizing flow channel 7 are symmetrically arranged about the axis of the electrode frame perpendicular to the flow direction of the electrolyte; the several guide blocks 10 in the inlet and outlet equalizing flow channel 3 are divided into several layers along the flow direction of the electrolyte, and the spacing between each layer is 4 mm; along the flow direction of the electrolyte, the number of guide blocks 10 in each layer gradually increases and the length of the guide blocks 10 gradually decreases; the guide blocks 10 in the inlet and outlet equalizing flow channel 3 and the outlet equalizing flow channel 7 are symmetrically arranged about the axis of the electrode frame parallel to the flow direction of the electrolyte.
[0027] refer to Figure 1 The liquid inlet comb-type flow channel 4 is provided with a plurality of linear arrays of liquid inlet comb-type supports 401, and the liquid outlet comb-type flow channel 8 is provided with a plurality of linear arrays of liquid outlet comb-type supports 801; the liquid inlet comb-type supports 401 and the liquid outlet comb-type supports 801 are both rectangular, and the length direction is parallel to the flow direction of the electrolyte.
[0028] refer to Figure 1 、 Figure 2 , further comprising a bipolar plate 11 covering the electrode frame, with a bipolar plate flow channel 1101 being defined on the bipolar plate 11. A bipolar plate fixing groove 12 is defined on the electrode frame, and a bipolar plate fixing block 1102 is provided on the bipolar plate 11, which is inserted into the bipolar plate fixing groove 12 for fixation.
[0029] refer to Figure 1 、 Figure 2 The bipolar plate channels 11 extend in the direction of electrolyte flow and are located between the inlet comb-shaped channels 4 and the outlet comb-shaped channels 8. Two adjacent bipolar plate channels 11 form a group. Within each group, one bipolar plate channel 11 connects to the inlet comb-shaped channels 4 but not to the outlet comb-shaped channels 8, while the other connects to the outlet comb-shaped channels 8 but not to the inlet comb-shaped channels 4. The distance between the closed end of the bipolar plate channel 11 and the inlet comb-shaped channels 4 is less than 10% of the width of the bipolar plate 11 and greater than the spacing between adjacent bipolar plate channels 11. Each bipolar plate channel 11 connects to one or two flow areas (at most three inlet comb-shaped supports 401 or three outlet comb-shaped supports 801 are contained within the bipolar plate channel 11).
[0030] refer to Figure 1 、 Figure 2 The bipolar plate flow channel 11 consists of an expansion area and a contraction area. The width W1 of the expansion area is equal to the width W2 of the contraction area. The lengths of the expansion area and the contraction area are equal and equal to 1 / 4 of the width L1 of the bipolar plate flow channel 11. The spacing L2 between two adjacent bipolar plate flow channels 11 is equal to the width L1 of the bipolar plate flow channel 11.
[0031] During operation, the electrolyte enters the electrode frame through the main inlet channel 1, flows through the inlet connecting channel 2, and then enters the inlet equalizing channel 3 from the horizontal center of the electrode frame. Due to the diversion effect of the inlet equalizing channel 3, the total flow rate before the inlet comb-shaped channel 4 is evenly distributed horizontally. After entering the bipolar plate 11, the electrolyte flow rate along the horizontal direction of the electrode frame is increased by the change in the flow cross-section within the bipolar plate channel 1101. The main outlet channel 5, the outlet connecting channel 6, the outlet equalizing channel 7, and the outlet comb-shaped channel 8 are symmetrical with the corresponding inlet channel about the center of the electrode frame to ensure consistency of the inlet and outlet flow rates.
[0032] Figure 2 As shown, the bipolar plate flow channel 11 can also have two cross-sectional structures, ab. In a, the width of the contracting section W3 is equal to the width of the expanding section W4, and the length of the contracting section L5 is half of the flow channel length L4. The angle between the expanding and contracting sections is 125°. In b, the radius of the circle is R, the width of the expanding section W5 is equal to 2R, and the length of the contracting section L7 is half of the flow channel length L6.
[0033] like Figure 3 As shown, Figure 3 (a) is a velocity vector diagram of a variable cross-section interdigital flow channel in an embodiment of the present application. Figure 3 (b) shows the velocity vector diagram for a conventional interdigital flow channel. It can be seen that compared to the conventional interdigital flow channel, the variable-cross-section interdigital flow channel in this embodiment exhibits a significant horizontal velocity component. As shown in Table 1, the average velocity in the electrode region increases by 15-20% compared to the conventional interdigital flow channel.
[0034] Table 1 Average velocity of variable cross-section interdigital flow channel and traditional flow channel in the electrode area
[0035]
[0036] The results of the examples show that the liquid flow battery electrode frame and bipolar plate with a flow equalization effect provided by the present application increase the electrolyte permeability in the horizontal direction of the reaction zone, enhance the mass transfer effect of the electrolyte between the electrode and the ion membrane, and reduce the internal resistance of concentration polarization.
[0037] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.
Claims
1. A liquid flow battery electrode frame and bipolar plate, characterized in that: The electrode frame comprises an electrode frame, on which a liquid inlet main channel (1), a liquid inlet connecting channel (2), a liquid inlet uniform flow channel (3), a liquid inlet comb-shaped channel (4), a liquid outlet main channel (5), a liquid outlet connecting channel (6), a liquid outlet uniform flow channel (7), and a liquid outlet comb-shaped channel (8) are provided; a support (9) is provided in the liquid inlet connecting channel (2) and the liquid outlet connecting channel (6), and the support (9) divides the liquid inlet connecting channel (2) and the liquid outlet connecting channel (6) into equal parts. The invention relates to a plurality of flow areas; the liquid inlet uniform flow channel (3) and the liquid outlet uniform flow channel (7) include a plurality of guide blocks (10); the liquid inlet comb-shaped flow channel (4) is provided with a plurality of linear arrays of liquid inlet comb-shaped supports (401), and the liquid outlet comb-shaped flow channel (8) is provided with a plurality of linear arrays of liquid outlet comb-shaped supports (801); and the invention also includes a bipolar plate (11) covering the electrode frame, and the bipolar plate (11) is provided with a bipolar plate flow channel (1101).
2. The flow battery electrode frame and bipolar plate according to claim 1, characterized in that: The widths of the plurality of flow areas are equal, and the liquid inlet communication flow channel (2) and the liquid outlet communication flow channel (6) are symmetrical about the center of the electrode frame.
3. The flow battery electrode frame and bipolar plate according to claim 2, characterized in that: The guide blocks (10) in the liquid inlet equalizing flow channel (3) and the liquid outlet equalizing flow channel (7) are symmetrically arranged about the axis of the electrode frame perpendicular to the flow direction of the electrolyte; the plurality of guide blocks (10) in the liquid inlet equalizing flow channel (3) are divided into a plurality of layers along the flow direction of the electrolyte, and the spacing between each layer is 3-5 mm; along the flow direction of the electrolyte, the number of guide blocks (10) in each layer gradually increases and the length of the guide blocks (10) gradually decreases; the guide blocks (10) in the liquid inlet equalizing flow channel (3) and the liquid outlet equalizing flow channel (7) are symmetrically arranged about the axis of the electrode frame parallel to the flow direction of the electrolyte.
4. The flow battery electrode frame and bipolar plate according to claim 3, characterized in that: The liquid inlet comb-shaped flow channel (4) and the liquid outlet comb-shaped flow channel (8) are symmetrically arranged; a flow area is formed between two adjacent liquid inlet comb-shaped supports (401), and the projection size of the flow area and the liquid inlet comb-shaped supports (401) on the electrode frame is the same.
5. The flow battery electrode frame and bipolar plate according to claim 4, characterized in that: A bipolar plate fixing groove (12) is provided on the electrode frame, a bipolar plate fixing block (1102) is provided on the bipolar plate (11), and the bipolar plate fixing block (1102) is inserted into the bipolar plate fixing groove (12) for fixing.
6. The flow battery electrode frame and bipolar plate according to claim 5, characterized in that: The bipolar plate flow channel (1101) extends in the direction of electrolyte flow, and the bipolar plate flow channel (1101) is located between the liquid inlet comb-shaped flow channel (4) and the liquid outlet comb-shaped flow channel (8); two adjacent bipolar plate flow channels (1101) form a group, and one bipolar plate flow channel (1101) in each group is connected to the liquid inlet comb-shaped flow channel (4) but not to the liquid outlet comb-shaped flow channel (8), and the other is connected to the liquid outlet comb-shaped flow channel (8) but not to the liquid inlet comb-shaped flow channel (4).
7. The flow battery electrode frame and bipolar plate according to claim 6, characterized in that: The distance between the closed end of the bipolar plate flow channel (1101) and the liquid inlet comb-shaped flow channel (4) is less than 10% of the width of the bipolar plate (11), and the distance is greater than the spacing between two adjacent bipolar plate flow channels (1101).
8. The flow battery electrode frame and bipolar plate according to claim 7, characterized in that: Each of the bipolar plate flow channels (1101) is connected to at least three of the flow areas.
9. The flow battery electrode frame and bipolar plate according to claim 8, characterized in that: The bipolar plate flow channel (1101) consists of an expansion area and a contraction area, the width W1 of the expansion area is equal to the width W2 of the contraction area, the length of the expansion area and the contraction area are equal and equal to 1 / 4 of the width L1 of the bipolar plate flow channel (1101), and the spacing L2 between two adjacent bipolar plate flow channels (1101) is equal to the interdigital flow channel width L1.