A flow field structure for flow batteries

Abstract

This invention belongs to the field of flow battery technology, specifically relating to a flow field structure for a flow battery, including a cathode flow field and an anode flow field, which are integrally formed. The cross-section of the integrally formed cathode and anode flow fields is approximately serpentine, with the cathode flow field on one side and the anode flow field on the other. The cathode flow field is suitable for the flow of cathode electrolyte, and the anode flow field is suitable for the flow of anode electrolyte. This invention's flow field structure for a flow battery, employing an integrally formed cathode and anode flow field with an approximately serpentine cross-section, can reduce the stack thickness, decrease volume, and lighten weight, while simultaneously improving structural integrity and stability.

Description

Technical Field

[0001] This utility model relates to the field of flow battery technology, and specifically to a flow field structure for flow batteries. Background Technology

[0002] Flow batteries, as a novel battery technology, offer advantages such as high efficiency, safety, reliability, and long cycle life. They effectively compensate for the inherent instability of renewable energy sources like solar and wind power, enabling stable and continuous power supply. The core reaction of a flow battery relies on the circulating flow of the electrolyte in the cathode and anode fields within the stack, along with electrochemical reactions. However, the large size of flow batteries results in a low volumetric power ratio, and their compact design necessitates ample space for practical applications, making a compact structure a pressing requirement for their large-scale deployment.

[0003] In existing technologies, the volume of flow batteries is limited by the flow field structure, such as Figure 1 As shown, the cathode flow field and anode flow field of a flow battery typically adopt a separate mounting structure, that is, they are respectively set on independent cathode flow field plates 200 and anode flow field plates 300; for example Figure 2 As shown, another existing independent cathode flow field plate 200 and anode flow field plate 300 are further separated by a partition plate 400. However, the stacking of independent cathode flow field plates 200 and anode flow field plates 300 results in a large reactor stack thickness, a large overall battery volume and weight, making it difficult to adapt to scenarios with strict space and weight constraints.

[0004] Therefore, it is necessary to provide new flow field structures for flow batteries. Utility Model Content

[0005] In view of this, the present invention provides a flow field structure for flow batteries. By adopting an integrally formed cathode flow field and an anode flow field with a roughly serpentine cross-section, the thickness of the battery stack can be reduced, the volume can be reduced, the weight can be reduced, and the overall structure and stability can be improved.

[0006] The technical solution adopted by this utility model to solve its technical problem is: a flow field structure for a flow battery is provided, including: a cathode flow field and an anode flow field, wherein the cathode flow field and the anode flow field are integrally formed; the cross-section of the integrally formed cathode flow field and anode flow field is approximately serpentine, with the cathode flow field on one side and the anode flow field on the other side, wherein the cathode flow field is suitable for the flow of cathode electrolyte and the anode flow field is suitable for the flow of anode electrolyte.

[0007] Furthermore, the cathode flow field includes multiple cathode grooves and multiple cathode ridges, which are arranged alternately.

[0008] Furthermore, the anode flow field includes multiple anode grooves and multiple anode ridges, which are arranged alternately.

[0009] Furthermore, the anode groove is formed on the opposite side of the cathode ridge, and the cathode groove is formed on the opposite side of the anode ridge.

[0010] Furthermore, the cathode ridge corresponds one-to-one with the anode groove on the opposite side, and the anode ridge corresponds one-to-one with the cathode groove on the opposite side.

[0011] Furthermore, the size of the cathode groove is the same as the size of the anode groove, and the size of the cathode ridge is the same as the size of the anode ridge.

[0012] Furthermore, the cross-sections of the cathode groove and the anode groove are rectangular.

[0013] Furthermore, the width of the cathode groove and the anode groove ranges from 0.6mm to 1.5mm.

[0014] Furthermore, the cross-sections of the cathode groove and the anode groove are trapezoidal or arc-shaped.

[0015] The beneficial effects of this invention are as follows: The flow field structure for a flow battery of this invention includes a cathode flow field and an anode flow field, which are integrally formed. The cross-section of the integrally formed cathode and anode flow fields is approximately serpentine, with the cathode flow field on one side and the anode flow field on the other. The cathode flow field is suitable for the flow of cathode electrolyte, and the anode flow field is suitable for the flow of anode electrolyte. By designing the cathode and anode flow fields as an integrally formed structure with an approximately serpentine cross-section, the flow field structure for a flow battery of this invention significantly reduces the thickness of the flow battery reactor stack compared to the separate cathode and anode flow field plates in the prior art, effectively reducing the battery volume and stack weight. At the same time, the integrally formed structure reduces the gaps and redundancy in the assembly of multiple components in the traditional separate structure, improving the integrity and stability of the flow field structure, which helps the electrolyte to be evenly distributed in the serpentine flow channel, ensuring the efficient electrochemical reaction, thereby improving the overall performance of the flow battery. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of a cross-section of a flow field structure in the prior art;

[0018] Figure 2 This is a schematic diagram of a cross-section of another flow field structure in the prior art;

[0019] Figure 3 This is a cross-sectional schematic diagram of the flow field structure for a flow battery provided in Embodiment 1 of this utility model;

[0020] Figure 4 This is a cross-sectional schematic diagram of the flow field structure for a flow battery provided in Embodiment 2 of this utility model;

[0021] Figure 5 This is a cross-sectional schematic diagram of the flow field structure, electrode layer, and proton membrane for a flow battery provided in Embodiment 2 of this utility model;

[0022] Figure 6 This is a cross-sectional schematic diagram of the flow field structure for a flow battery provided in Embodiment 3 of this utility model;

[0023] Figure 7 This is a cross-sectional schematic diagram of the flow field structure, electrode layer, and proton membrane for a flow battery provided in Embodiment 3 of this utility model.

[0024] The component names and their numbers in the diagram are as follows:

[0025] Flow field structure 100 for flow batteries;

[0026] Cathode flow field 1, cathode groove 11, surface cathode groove 111, inner cathode groove 112, cathode ridge 12;

[0027] Anode flow field 2, anode groove 21, surface anode groove section 211, inner anode groove section 212, anode ridge 22;

[0028] Electrode layer 3, proton membrane 4;

[0029] Cathode flow field plate 200; Anode flow field plate 300; Separator plate 400. Detailed Implementation

[0030] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0031] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0035] Example 1

[0036] like Figure 3 As shown, this embodiment provides a flow field structure 100 for a flow battery, including a cathode flow field 1 and an anode flow field 2, which are integrally formed. The cross-section of the integrally formed cathode flow field 1 and anode flow field 2 is approximately serpentine, with the cathode flow field 1 on one side and the anode flow field 2 on the other. The cathode flow field 1 is suitable for the flow of cathode electrolyte, and the anode flow field 2 is suitable for the flow of anode electrolyte. The integrally formed cathode flow field 1 and anode flow field 2 are used in a manner that is relatively... Figure 1 , Figure 2 The separately configured cathode flow field plate 200, anode flow field plate 300 (and separator plate 400) structure shown can reduce the thickness of the flow battery reactor stack, reduce the battery volume, and reduce the weight of the flow battery stack.

[0037] In some embodiments, the cathode flow field 1 includes multiple cathode grooves 11 and multiple cathode ridges 12, which are alternately arranged. Adjacent cathode grooves 11 and cathode ridges 12 cooperate with each other to provide a precise path for the flow and reaction of the electrolyte. The anode flow field 2 includes multiple anode grooves 21 and multiple anode ridges 22, which are alternately arranged. An anode groove 21 is formed on the opposite side of a cathode ridge 12, and a cathode groove 11 is formed on the opposite side of an anode ridge 22, thereby achieving the integration of the cathode flow field 1 and anode flow field 2 structures and realizing a high degree of integration in the spatial utilization of the cathode flow field 1 and anode flow field 2. That is, the cathode ridge 12 corresponds one-to-one with the anode groove 21 on the opposite side, and the anode ridge 22 corresponds one-to-one with the cathode groove 11 on the opposite side. The size of the cathode groove 11 is the same as the size of the anode groove 21, and the size of the cathode ridge 12 is the same as the size of the anode ridge 22. The cross-section of the cathode groove 11 and the anode groove 21 is rectangular, which simplifies the processing technology and effectively reduces the technical difficulty and cost input in the manufacturing process. The widths of the cathode tank 11 and the anode tank 21 range from approximately 0.6 mm to 1.5 mm, ensuring both smooth electrolyte flow and sufficient contact with the electrodes for efficient participation in the electrochemical reaction. This design achieves both a compact flow field structure and adequate battery performance requirements.

[0038] In some other embodiments not shown in the figures, the cross-sections of the cathode tank 11 and the anode tank 21 are trapezoidal or arc-shaped, which can reduce the resistance to electrolyte flow, reduce energy loss, and thus improve the flow efficiency of the electrolyte.

[0039] The flow field structure 100 for a flow battery of this invention includes a cathode flow field 1 and an anode flow field 2, which are integrally formed. The cross-section of the integrally formed cathode flow field 1 and anode flow field 2 is approximately serpentine, with the cathode flow field 1 on one side and the anode flow field 2 on the other side. The cathode flow field 1 includes multiple cathode grooves 11 and multiple cathode ridges 12, which are alternately arranged. The anode flow field 2 includes multiple anode grooves 21 and multiple anode ridges 22, which are alternately arranged. The flow field structure 100 for flow batteries of this invention adopts an integrated cathode flow field 1 and anode flow field 2 structure. Compared with separately set cathode and anode flow field plates, it can significantly reduce the thickness of the flow battery reactor stack, effectively reduce the battery volume, and reduce the weight of the flow battery stack, making it suitable for scenarios with strict requirements on layout space. The design of one-to-one correspondence between cathode ridge 12 and anode groove 21, and one-to-one correspondence between anode ridge 22 and cathode groove 11, realizes the integration of cathode flow field 1 and anode flow field 2 structures, makes full use of space, avoids the waste of space in traditional separate structures, and further ensures the compactness of the stack. At the same time, the integrated structure reduces the gaps and redundancy of multi-component assembly in traditional separate structures, improves the integrity and stability of the flow field structure, helps the electrolyte to be evenly distributed in the serpentine flow channel, ensures the efficient electrochemical reaction, and thus improves the overall performance of the flow battery.

[0040] Example 2

[0041] like Figure 4 As shown, the flow field structure 100 for a flow battery of this invention includes a cathode flow field 1 and an anode flow field 2 disposed on the opposite side of the cathode flow field 1. The cathode flow field 1 and the anode flow field 2 are symmetrically arranged. The cathode flow field 1 is suitable for the flow of cathode electrolyte, and the anode flow field 2 is suitable for the flow of anode electrolyte.

[0042] In some embodiments, the cathode flow field 1 includes multiple cathode grooves 11 and multiple cathode ridges 12, which are alternately arranged. Adjacent cathode grooves 11 and cathode ridges 12 cooperate with each other to provide a precise path for the flow and reaction of the electrolyte. The anode flow field 2 includes multiple anode grooves 21 and multiple anode ridges 22, which are alternately arranged. The opposite side of the cathode groove 11 is the anode groove 21, and the opposite side of the cathode ridge 12 is the anode ridge 22. Furthermore, the cathode grooves 11 and anode grooves 21 have the same shape and size, and the cathode ridges 12 and anode ridges 22 have the same shape and size.

[0043] In some embodiments, the cathode tank 11 is generally T-shaped, and the cathode electrolyte forms a double-layer flow channel as it flows within the cathode tank 11. The cathode tank 11 includes a surface cathode tank portion 111 and an inner cathode tank portion 112, such as... Figure 5As shown, an electrode layer 3 and a proton exchange membrane 4 of a flow battery are attached to one side of the surface cathode tank 111. The electrode layer 3 is made of a porous material (such as carbon felt), and its porous structure provides a diffusion path for active substances in the electrolyte (such as vanadium ions in a vanadium redox flow battery), ensuring that the active substances are rapidly transported from the electrolyte in the flow field to the surface of the proton exchange membrane 4 to participate in redox reactions. The proton exchange membrane 4 only allows protons to pass through, ensuring that protons can migrate from one electrode to another during the charging / discharging process of the flow battery, maintaining charge balance. In addition, the positive and negative electrode electrolytes of a flow battery usually contain different active substances (such as vanadium ions of different valence states in a vanadium redox flow battery), and the proton exchange membrane physically isolates the positive and negative electrode electrolytes to prevent mixing. Since the electrode layer 3 and proton exchange membrane 4 of the flow battery are attached to one side of the surface cathode tank 111, the cathode electrolyte and anolyte produce an electrochemical reaction at the proton exchange membrane 4. The electrochemical reaction produces side reaction gases that generate bubbles at the proton exchange membrane 4 and electrode layer 3, which will hinder the contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, thus affecting the reaction efficiency of the flow battery.

[0044] The width of the inner cathode groove 112 Width greater than the surface cathode groove 111 And the cross-sectional area of ​​the inner cathode groove 112 The cross-sectional area of ​​the surface cathode groove 111 is greater than that of the surface cathode groove. When the cathode electrolyte flows into the cathode tank 11, due to the cross-sectional area of ​​the inner cathode tank portion 112... The cross-sectional area of ​​the surface cathode groove 111 is greater than that of the surface cathode groove. Since the inner cathode groove 112 has a larger flow cross-sectional area than the outer cathode groove 111, the flow resistance of the cathode electrolyte in the inner cathode groove 112 is smaller; since the outer cathode groove 111 has a smaller flow cross-sectional area than the inner cathode groove 112, the flow resistance of the cathode electrolyte in the inner cathode groove 112 is larger.

[0045] Specifically, because the inner cathode tank 112 has a larger flow cross-sectional area compared to the outer cathode tank 111, the flow resistance of the cathode electrolyte in the inner cathode tank 112 is smaller; conversely, because the outer cathode tank 111 has a smaller flow cross-sectional area compared to the inner cathode tank 112, the flow resistance of the cathode electrolyte in the inner cathode tank 112 is larger. The flow velocity of the cathode electrolyte in the inner cathode tank 112 is greater than that in the outer cathode tank 111. According to Bernoulli's principle, in a horizontal flow channel, the static pressure is lower where the flow velocity is higher, and higher where the flow velocity is lower. In the cathode tank 11, the cathode electrolyte in the inner cathode tank 112 has a high flow velocity and low static pressure; the cathode electrolyte in the outer cathode tank 111 has a low flow velocity and high static pressure. This creates a pressure gradient in the vertical direction, where the pressure in the inner cathode tank 112 is lower than that in the outer cathode tank 111. Because the side reaction gas generates bubbles at the proton exchange membrane 4 and electrode layer 3 and is located in the surface cathode tank 111, and because the electrolyte static pressure in the surface cathode tank 111 is high while the electrolyte static pressure in the inner cathode tank 112 is low, there is a pressure difference between the surface cathode tank 111 and the inner cathode tank 112. The bubbles are attracted towards the inner cathode tank 112 with lower pressure. Driven by the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure surface cathode tank 111 region to the low-pressure inner cathode tank 112 region, thereby driving the bubbles away from the electrode layer 3 and proton exchange membrane 4 in the inner cathode tank 112 region. This achieves the effect of active separation of bubbles in the surface cathode tank 111 region, ensuring effective contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, and improving the reaction efficiency of the flow battery.

[0046] Similarly, the anode tank 21 is roughly T-shaped, forming a double-layer flow channel as the anolyte flows within it. The anode tank 21 includes a surface anode tank section 211 and an inner anode tank section 212. The surface anode tank section 211 has an electrode layer 3 and a proton exchange membrane 4 attached to one side. The electrode layer 3 is made of a porous material (such as carbon felt), and its porous structure provides a diffusion path for active substances in the electrolyte (such as vanadium ions in a vanadium redox flow battery), ensuring that the active substances are rapidly transported from the electrolyte in the flow field to the surface of the proton exchange membrane 4 to participate in redox reactions. The proton exchange membrane 4 only allows protons to pass through, ensuring that protons can migrate from one electrode to another during charging / discharging, maintaining charge balance. Furthermore, the positive and negative electrode electrolytes of a flow battery typically contain different active substances (such as vanadium ions of different valence states in a vanadium redox flow battery), and the proton exchange membrane physically isolates the positive and negative electrode electrolytes, preventing mixing. Since the electrode layer 3 and proton exchange membrane 4 of the flow battery are attached to one side of the surface anode tank 211, the anolyte and the anolyte undergo an electrochemical reaction at the proton exchange membrane 4. The electrochemical reaction produces side reaction gases that generate bubbles at the proton exchange membrane 4 and electrode layer 3, which will hinder the contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, thus affecting the reaction efficiency of the flow battery.

[0047] Among them, the width of the inner anode groove 212 Width greater than the surface anode groove 211 And the cross-sectional area of ​​the inner anode groove 212 The cross-sectional area is greater than that of the surface anode groove 211 When the anolyte flows into the anode tank 21, due to the cross-sectional area of ​​the inner anode tank section 212... The cross-sectional area is greater than that of the surface anode groove 211 Since the inner anode groove 212 has a larger flow cross-sectional area than the outer anode groove 211, the flow resistance of the anode electrolyte in the inner anode groove 212 is smaller; since the outer anode groove 211 has a smaller flow cross-sectional area than the inner anode groove 212, the flow resistance of the anode electrolyte in the inner anode groove 212 is larger.

[0048] Specifically, because the inner anode tank 212 has a larger flow cross-sectional area compared to the outer anode tank 211, the flow resistance of the anolyte in the inner anode tank 212 is lower; conversely, because the outer anode tank 211 has a smaller flow cross-sectional area compared to the inner anode tank 212, the flow resistance of the anolyte in the inner anode tank 212 is higher. The flow velocity of the anolyte in the inner anode tank 212 is greater than that in the outer anode tank 211. According to Bernoulli's principle, in a horizontal flow channel, the static pressure is lower where the flow velocity is higher, and higher where the flow velocity is lower. In the anode tank 21, the anolyte in the inner anode tank 212 has a high flow velocity and low static pressure; the anolyte in the outer anode tank 211 has a low flow velocity and high static pressure. This creates a pressure gradient in the vertical direction, where the pressure in the inner anode tank 212 is lower than that in the outer anode tank 211. Because the side reaction gas generates bubbles at the proton exchange membrane 4 and electrode layer 3 and is located in the surface anode tank 211, and because the electrolyte static pressure in the surface anode tank 211 is high while the electrolyte static pressure in the inner anode tank 212 is low, there is a pressure difference between the surface anode tank 211 and the inner anode tank 212. The bubbles are attracted towards the inner anode tank 212 with lower pressure. Driven by the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure surface anode tank 211 region to the low-pressure inner anode tank 212 region, thereby driving the bubbles away from the electrode layer 3 and proton exchange membrane 4 in the inner anode tank 212 region. This achieves the effect of active separation of bubbles in the surface anode tank 211 region, ensuring effective contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, and improving the reaction efficiency of the flow battery.

[0049] In some embodiments, the pressure difference between the inner cathode tank 112 and the outer cathode tank 111 is ΔP, and the difference between the electrolyte flow rate in the inner cathode tank 112 and the electrolyte flow rate in the outer cathode tank 111 is ΔP. The cross-sectional area of ​​the inner cathode groove 112 The cross-sectional area of ​​the surface cathode groove 111 The difference is Δ According to Bernoulli's principle, ΔP and Δ With 1 / Δ The relationship is directly proportional; if the cross-sectional area of ​​the surface cathode groove 111 is... Significantly smaller than the cross-sectional area of ​​the inner cathode groove 112 The decrease in bottom flow velocity and increase in static pressure can drive bubbles to migrate upwards.

[0050] Specifically, the electrolyte flow rate in the surface cathode tank 111 ≈ Total flow rate / Cross-sectional area of ​​surface cathode groove 111 Electrolyte flow rate in the inner cathode tank 112 ≈ Total flow rate / Cross-sectional area of ​​inner cathode groove 112 Then the pressure difference is ΔP = 0.5ρ( - ), where ρ is the electrolyte density. When ΔP ≥ 50–100 Pa, it can drive the migration of bubbles of 0.1–1 mm.

[0051] As an example, the width of the inner cathode groove 112 Width of the surface cathode groove 111 The ratio is greater than 1.5:1, and the cross-sectional area of ​​the inner cathode groove 112 is... The cross-sectional area of ​​the surface cathode groove 111 The ratio is greater than 2:1.

[0052] Similarly, let the pressure difference between the inner anode tank 212 and the outer anode tank 211 be ΔP, and the difference in electrolyte flow rate between the inner anode tank 212 and the outer anode tank 211 be ΔP. The cross-sectional area of ​​the inner anode groove 212 The cross-sectional area of ​​the surface anode groove 211 The difference is Δ According to Bernoulli's principle, ΔP and Δ With 1 / Δ The relationship is directly proportional; if the cross-sectional area of ​​the surface anode groove 211 is... Significantly smaller than the cross-sectional area of ​​the inner anode groove 212 The decrease in bottom flow velocity and increase in static pressure can drive bubbles to migrate upwards.

[0053] Specifically, the electrolyte flow rate in the surface anode tank 211 ≈ Total flow rate / Cross-sectional area of ​​surface anode tank 211 The electrolyte flow rate in the inner anode tank 212 ≈ Total flow rate / Cross-sectional area of ​​inner anode tank 212 Then the pressure difference is ΔP = 0.5ρ( - ), where ρ is the electrolyte density. When ΔP ≥ 50–100 Pa, it can drive the migration of bubbles of 0.1–1 mm.

[0054] As an example, the width of the inner anode groove 212 Width of the surface anode groove 211 The ratio is greater than 1.5:1, and the cross-sectional area of ​​the inner anode groove 212 is... The cross-sectional area of ​​the surface anode groove 211 The ratio is greater than 2:1.

[0055] In some other embodiments not shown in the figures, the cathode tank 11 and the anode tank 21 are two tanks with different shapes and cross-sectional areas, which can create a pressure difference between the two tanks. As a result, under the drive of the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure area to the low-pressure area, thereby driving the bubbles away from the electrode layer 3 and the proton membrane 4.

[0056] The flow field structure 100 of this utility model for a flow battery is symmetrically arranged with cathode flow field 2 and anode flow field 2, and the cathode groove 11 and anode groove 21, cathode ridge 12 and anode ridge 22 have the same shape and size, ensuring that the electrolyte flow state is consistent at the cathode and anode, thus improving the stability of battery operation. The T-shaped groove design creates a pressure gradient through the difference in cross-sectional area, resulting in high pressure on the surface and low pressure on the inner layer. The Bernoulli principle drives the bubbles generated by the side reaction to migrate from the surface groove near the electrode layer 3 and proton exchange membrane 4 to the inner groove, avoiding bubbles from hindering the contact between the electrolyte and the core reaction components, thus significantly improving the electrochemical reaction efficiency. Through the bubble separation effect, it is ensured that the electrode layer 3 and proton exchange membrane 4 are always in effective contact with the electrolyte, providing a stable environment for the redox reaction and reducing performance fluctuations caused by bubbles.

[0057] Example 3

[0058] like Figure 6 As shown, the flow field structure 100 for a flow battery of this invention includes a cathode flow field 1 and an anode flow field 2, which are integrally formed. The cross-section of the integrally formed cathode flow field 1 and anode flow field 2 is approximately serpentine, with the cathode flow field 1 on one side and the anode flow field 2 on the other side. The cathode flow field 1 is suitable for the flow of cathode electrolyte, and the anode flow field 2 is suitable for the flow of anode electrolyte. By using the integrally formed cathode flow field 1 and anode flow field 2, compared with the separately set cathode flow field plate and anode flow field plate structure, the thickness of the flow battery reactor stack can be reduced, the battery volume can be reduced, and the weight of the flow battery stack can be reduced.

[0059] In some embodiments, the cathode flow field 1 includes multiple cathode grooves 11 and multiple cathode ridges 12, which are alternately arranged. Adjacent cathode grooves 11 and cathode ridges 12 cooperate with each other to provide a precise path for the flow and reaction of the electrolyte. The anode flow field 2 includes multiple anode grooves 21 and multiple anode ridges 22, which are alternately arranged. An anode groove 21 is formed on the opposite side of a cathode ridge 12, and a cathode groove 11 is formed on the opposite side of an anode ridge 22, thereby achieving the integration of the structures of the cathode flow field 1 and the anode flow field 2, and realizing a high degree of integration in the spatial utilization of the cathode flow field 1 and the anode flow field 2. That is, the cathode ridge 12 corresponds one-to-one with the anode groove 21 on the opposite side, and the anode ridge 22 corresponds one-to-one with the cathode groove 11 on the opposite side. The size of the cathode groove 11 is the same as the size of the anode groove 21, and the size of the cathode ridge 12 is the same as the size of the anode ridge 22.

[0060] In some embodiments, the cathode tank 11 is generally T-shaped, and the cathode electrolyte forms a double-layer flow channel as it flows within the cathode tank 11. The cathode tank 11 includes a surface cathode tank portion 111 and an inner cathode tank portion 112, such as... Figure 7 As shown, an electrode layer 3 and a proton exchange membrane 4 of a flow battery are attached to one side of the surface cathode tank 111. The electrode layer 3 is made of a porous material (such as carbon felt), and its porous structure provides a diffusion path for active substances in the electrolyte (such as vanadium ions in a vanadium redox flow battery), ensuring that the active substances are rapidly transported from the electrolyte in the flow field to the surface of the proton exchange membrane 4 to participate in redox reactions. The proton exchange membrane 4 only allows protons to pass through, ensuring that protons can migrate from one electrode to another during the charging / discharging process of the flow battery, maintaining charge balance. In addition, the positive and negative electrode electrolytes of a flow battery usually contain different active substances (such as vanadium ions of different valence states in a vanadium redox flow battery), and the proton exchange membrane physically isolates the positive and negative electrode electrolytes to prevent mixing. Since the electrode layer 3 and proton exchange membrane 4 of the flow battery are attached to one side of the surface cathode tank 111, the cathode electrolyte and anolyte produce an electrochemical reaction at the proton exchange membrane 4. The electrochemical reaction produces side reaction gases that generate bubbles at the proton exchange membrane 4 and electrode layer 3, which will hinder the contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, thus affecting the reaction efficiency of the flow battery.

[0061] The width of the inner cathode groove 112 Width greater than the surface cathode groove 111 And the cross-sectional area of ​​the inner cathode groove 112 The cross-sectional area of ​​the surface cathode groove 111 is greater than that of the surface cathode groove. When the cathode electrolyte flows into the cathode tank 11, due to the cross-sectional area of ​​the inner cathode tank portion 112... The cross-sectional area of ​​the surface cathode groove 111 is greater than that of the surface cathode groove. Since the inner cathode groove 112 has a larger flow cross-sectional area than the outer cathode groove 111, the flow resistance of the cathode electrolyte in the inner cathode groove 112 is smaller; since the outer cathode groove 111 has a smaller flow cross-sectional area than the inner cathode groove 112, the flow resistance of the cathode electrolyte in the inner cathode groove 112 is larger.

[0062] Specifically, because the inner cathode tank 112 has a larger flow cross-sectional area compared to the outer cathode tank 111, the flow resistance of the cathode electrolyte in the inner cathode tank 112 is smaller; conversely, because the outer cathode tank 111 has a smaller flow cross-sectional area compared to the inner cathode tank 112, the flow resistance of the cathode electrolyte in the inner cathode tank 112 is larger. The flow velocity of the cathode electrolyte in the inner cathode tank 112 is greater than that in the outer cathode tank 111. According to Bernoulli's principle, in a horizontal flow channel, the static pressure is lower where the flow velocity is higher, and higher where the flow velocity is lower. In the cathode tank 11, the cathode electrolyte in the inner cathode tank 112 has a high flow velocity and low static pressure; the cathode electrolyte in the outer cathode tank 111 has a low flow velocity and high static pressure. This creates a pressure gradient in the vertical direction, where the pressure in the inner cathode tank 112 is lower than that in the outer cathode tank 111. Because the side reaction gas generates bubbles at the proton exchange membrane 4 and electrode layer 3 and is located in the surface cathode tank 111, and because the electrolyte static pressure in the surface cathode tank 111 is high while the electrolyte static pressure in the inner cathode tank 112 is low, there is a pressure difference between the surface cathode tank 111 and the inner cathode tank 112. The bubbles are attracted towards the inner cathode tank 112 with lower pressure. Driven by the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure surface cathode tank 111 region to the low-pressure inner cathode tank 112 region, thereby driving the bubbles away from the electrode layer 3 and proton exchange membrane 4 in the inner cathode tank 112 region. This achieves the effect of active separation of bubbles in the surface cathode tank 111 region, ensuring effective contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, and improving the reaction efficiency of the flow battery.

[0063] Similarly, the anode tank 21 is roughly T-shaped, forming a double-layer flow channel as the anolyte flows within it. The anode tank 21 includes a surface anode tank section 211 and an inner anode tank section 212. The surface anode tank section 211 has an electrode layer 3 and a proton exchange membrane 4 attached to one side. The electrode layer 3 is made of a porous material (such as carbon felt), and its porous structure provides a diffusion path for active substances in the electrolyte (such as vanadium ions in a vanadium redox flow battery), ensuring that the active substances are rapidly transported from the electrolyte in the flow field to the surface of the proton exchange membrane 4 to participate in redox reactions. The proton exchange membrane 4 only allows protons to pass through, ensuring that protons can migrate from one electrode to another during charging / discharging, maintaining charge balance. Furthermore, the positive and negative electrode electrolytes of a flow battery typically contain different active substances (such as vanadium ions of different valence states in a vanadium redox flow battery), and the proton exchange membrane physically isolates the positive and negative electrode electrolytes, preventing mixing. Since the electrode layer 3 and proton exchange membrane 4 of the flow battery are attached to one side of the surface anode tank 211, the anolyte and the anolyte undergo an electrochemical reaction at the proton exchange membrane 4. The electrochemical reaction produces side reaction gases that generate bubbles at the proton exchange membrane 4 and electrode layer 3, which will hinder the contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, thus affecting the reaction efficiency of the flow battery.

[0064] Among them, the width of the inner anode groove 212 Width greater than the surface anode groove 211 And the cross-sectional area of ​​the inner anode groove 212 The cross-sectional area is greater than that of the surface anode groove 211 When the anolyte flows into the anode tank 21, due to the cross-sectional area of ​​the inner anode tank section 212... The cross-sectional area is greater than that of the surface anode groove 211 Since the inner anode groove 212 has a larger flow cross-sectional area than the outer anode groove 211, the flow resistance of the anode electrolyte in the inner anode groove 212 is smaller; since the outer anode groove 211 has a smaller flow cross-sectional area than the inner anode groove 212, the flow resistance of the anode electrolyte in the inner anode groove 212 is larger.

[0065] Specifically, because the inner anode tank 212 has a larger flow cross-sectional area compared to the outer anode tank 211, the flow resistance of the anolyte in the inner anode tank 212 is lower; conversely, because the outer anode tank 211 has a smaller flow cross-sectional area compared to the inner anode tank 212, the flow resistance of the anolyte in the inner anode tank 212 is higher. The flow velocity of the anolyte in the inner anode tank 212 is greater than that in the outer anode tank 211. According to Bernoulli's principle, in a horizontal flow channel, the static pressure is lower where the flow velocity is higher, and higher where the flow velocity is lower. In the anode tank 21, the anolyte in the inner anode tank 212 has a high flow velocity and low static pressure; the anolyte in the outer anode tank 211 has a low flow velocity and high static pressure. This creates a pressure gradient in the vertical direction, where the pressure in the inner anode tank 212 is lower than that in the outer anode tank 211. Because the side reaction gas generates bubbles at the proton exchange membrane 4 and electrode layer 3 and is located in the surface anode tank 211, and because the electrolyte static pressure in the surface anode tank 211 is high while the electrolyte static pressure in the inner anode tank 212 is low, there is a pressure difference between the surface anode tank 211 and the inner anode tank 212. The bubbles are attracted towards the inner anode tank 212 with lower pressure. Driven by the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure surface anode tank 211 region to the low-pressure inner anode tank 212 region, thereby driving the bubbles away from the electrode layer 3 and proton exchange membrane 4 in the inner anode tank 212 region. This achieves the effect of active separation of bubbles in the surface anode tank 211 region, ensuring effective contact between the electrolyte and the electrode layer 3 and proton exchange membrane 4, and improving the reaction efficiency of the flow battery.

[0066] In some embodiments, the pressure difference between the inner cathode tank 112 and the outer cathode tank 111 is ΔP, and the difference between the electrolyte flow rate in the inner cathode tank 112 and the electrolyte flow rate in the outer cathode tank 111 is ΔP. The cross-sectional area of ​​the inner cathode groove 112 The cross-sectional area of ​​the surface cathode groove 111 The difference is Δ According to Bernoulli's principle, ΔP and Δ With 1 / Δ The relationship is directly proportional; if the cross-sectional area of ​​the surface cathode groove 111 is... Significantly smaller than the cross-sectional area of ​​the inner cathode groove 112 The decrease in bottom flow velocity and increase in static pressure can drive bubbles to migrate upwards.

[0067] Specifically, the electrolyte flow rate in the surface cathode tank 111 ≈ Total flow rate / Cross-sectional area of ​​surface cathode groove 111 Electrolyte flow rate in the inner cathode tank 112 ≈ Total flow rate / Cross-sectional area of ​​inner cathode groove 112 Then the pressure difference is ΔP = 0.5ρ( - ), where ρ is the electrolyte density. When ΔP ≥ 50–100 Pa, it can drive the migration of bubbles of 0.1–1 mm.

[0068] As an example, the width of the inner cathode groove 112 Width of the surface cathode groove 111 The ratio is greater than 1.5:1, and the cross-sectional area of ​​the inner cathode groove 112 is... The cross-sectional area of ​​the surface cathode groove 111 The ratio is greater than 2:1.

[0069] Similarly, let the pressure difference between the inner anode tank 212 and the outer anode tank 211 be ΔP, and the difference in electrolyte flow rate between the inner anode tank 212 and the outer anode tank 211 be ΔP. The cross-sectional area of ​​the inner anode groove 212 The cross-sectional area of ​​the surface anode groove 211 The difference is Δ According to Bernoulli's principle, ΔP and Δ With 1 / Δ The relationship is directly proportional; if the cross-sectional area of ​​the surface anode groove 211 is... Significantly smaller than the cross-sectional area of ​​the inner anode groove 212 The decrease in bottom flow velocity and increase in static pressure can drive bubbles to migrate upwards.

[0070] Specifically, the electrolyte flow rate in the surface anode tank 211 ≈ Total flow rate / Cross-sectional area of ​​surface anode tank 211 The electrolyte flow rate in the inner anode tank 212 ≈ Total flow rate / Cross-sectional area of ​​inner anode tank 212 Then the pressure difference is ΔP = 0.5ρ( - ), where ρ is the electrolyte density. When ΔP ≥ 50–100 Pa, it can drive the migration of bubbles of 0.1–1 mm.

[0071] As an example, the width of the inner anode groove 212 Width of the surface anode groove 211 The ratio is greater than 1.5:1, and the cross-sectional area of ​​the inner anode groove 212 is... The cross-sectional area of ​​the surface anode groove 211 The ratio is greater than 2:1.

[0072] In some other embodiments not shown in the figures, the cathode tank 11 and the anode tank 21 are two tanks with different shapes and cross-sectional areas, which can create a pressure difference between the two tanks. As a result, under the drive of the pressure gradient, the bubbles generated by the side reaction will spontaneously migrate from the high-pressure area to the low-pressure area, thereby driving the bubbles away from the electrode layer 3 and the proton membrane 4.

[0073] The cathode flow field 1 and anode flow field 2 of the flow field structure 100 of this utility model for flow batteries adopt an integrated molding design. Compared with the traditional separate flow field plate structure, it significantly reduces the thickness of the reactor stack, shrinks the battery volume and reduces the weight, and achieves a high degree of spatial coupling between the cathode flow field 1 and the anode flow field 2, avoiding the space waste of the traditional structure and further enhancing the structural compactness. The double-layer channel of the integrated T-shaped groove uses the pressure gradient to drive the bubbles to migrate from the surface groove to the inner groove, which not only retains the advantages of the integrated molding structure, but also solves the problem of bubbles hindering the reaction, thus achieving both volume reduction and improved reaction efficiency of the flow battery.

[0074] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A flow field structure for a flow battery, characterized by, include: The cathode flow field and the anode flow field are integrally formed structures; The cross-sections of the integrally formed cathode flow field and anode flow field are approximately serpentine, with the cathode flow field on one side and the anode flow field on the other side. The cathode flow field is suitable for the flow of cathode electrolyte, and the anode flow field is suitable for the flow of anode electrolyte.

2. The flow field structure for a flow battery according to claim 1, characterized in that, The cathode flow field includes multiple cathode slots and multiple cathode ridges, which are arranged alternately.

3. The flow field structure for a flow battery according to claim 2, characterized in that, The anode flow field includes multiple anode grooves and multiple anode ridges, which are arranged alternately.

4. The flow field structure for a flow battery according to claim 3, characterized in that, The anode groove is formed on the opposite side of the cathode ridge, and the cathode groove is formed on the opposite side of the anode ridge.

5. The flow field structure for a flow battery according to claim 4, characterized in that, The cathode ridge corresponds one-to-one with the anode groove on the opposite side, and the anode ridge corresponds one-to-one with the cathode groove on the opposite side.

6. The flow field structure for a flow battery according to claim 3, characterized in that, The cathode groove has the same dimensions as the anode groove, and the cathode ridge has the same dimensions as the anode ridge.

7. The flow field structure for a flow battery according to claim 3, characterized in that, The cross-sections of the cathode groove and the anode groove are rectangular.

8. The flow field structure for a flow battery according to claim 7, characterized in that, The width of the cathode groove and the anode groove ranges from 0.6 mm to 1.5 mm.

9. The flow field structure for a flow battery according to claim 3, characterized in that, The cross-sections of the cathode and anode slots are trapezoidal or arc-shaped.

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