Electrode plate frame for flow battery and flow battery

Abstract

This application provides an electrode plate frame and a flow battery, relating to the field of battery technology. The specific technical solution is as follows: the electrode plate frame includes a frame body with an electrode cavity formed thereon; the frame body has a flow channel structure, including a primary flow channel, a secondary flow channel, and a tertiary flow channel. There are multiple secondary flow channels, and in two adjacent secondary flow channels, the cross-sectional area of ​​the secondary flow channel furthest from the outlet is larger than that of the secondary flow channel closest to the outlet. Each secondary flow channel is connected to multiple tertiary flow channels, and in two adjacent tertiary flow channels, the cross-sectional area of ​​the tertiary flow channel furthest from the first outlet is larger than that of the tertiary flow channel closest to the first outlet. This solution can reduce the degree of concentration polarization of the electrolyte on the electrode surface, resulting in a more uniform concentration distribution of active materials in the electrolyte on the electrode surface, which helps improve the energy efficiency of the flow battery and reduces the power consumption of the drive pump.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to an electrode plate frame and a flow battery. Background Technology

[0002] The current global energy structure's over-reliance on fossil fuels has led to a growing energy crisis, making the shift towards low-carbon and clean energy consumption an international consensus. To effectively address the challenges of integrating renewable energy into the grid and ensure grid security, large-scale energy storage technology has become a key support. Among numerous large-scale energy storage technologies, flow batteries, with their inherent safety and long cycle life, are considered a highly promising technology.

[0003] In flow batteries, the electrolyte typically enters the electrode cavity through the flow channel structure of the electrode plate frame and undergoes a redox reaction on the electrodes within the cavity. However, inadequate flow channel design in related technologies leads to uneven concentration distribution of active materials in the electrolyte on the electrode surface, causing significant concentration polarization and affecting the energy efficiency of the flow battery. While some related technologies optimize the flow channel structure of the electrode plate frame to reduce concentration polarization, this results in higher power consumption for the pump driving the electrolyte flow.

[0004] Therefore, designing a flow channel structure that can reduce the power consumption of the drive pump, reduce concentration polarization, and improve the energy efficiency of the flow battery is an urgent problem to be solved in the current field. Summary of the Invention

[0005] This application provides an electrode plate frame and a flow battery, which can reduce the degree of concentration polarization of the electrolyte on the electrode surface, making the concentration distribution of active materials in the electrolyte on the electrode surface uniform, which helps to improve the energy efficiency of the flow battery and can reduce the power consumption of the drive pump.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, an electrode plate frame for a flow battery is provided. The electrode plate frame includes a frame body with an electrode cavity formed thereon. A flow channel structure is provided on the frame body, communicating with the electrode cavity and used to supply electrolyte flow. The electrolyte can enter the electrode cavity through the flow channel structure, allowing for sufficient contact between the electrolyte and the electrode, and enabling a redox reaction to occur on the electrode within the electrode cavity.

[0008] The flow channel structure includes a primary flow channel, a secondary flow channel, and a tertiary flow channel. The secondary flow channel is located on the side of the tertiary flow channel furthest from the electrode cavity, and the primary flow channel is located on the side of the secondary flow channel furthest from the tertiary flow channel. The primary flow channel has an outlet, the secondary flow channel has a first inlet and a first outlet, and the tertiary flow channel has a second inlet and a second outlet. The first inlet communicates with the outlet, the second inlet communicates with the first outlet, and the second outlet communicates with the electrode cavity. The electrolyte entering the flow channel structure can enter the electrode cavity through the second inlet.

[0009] There are multiple secondary flow channels, which are spaced apart in the circumferential direction of the electrode cavity. Each secondary flow channel is connected to multiple tertiary flow channels, which are also spaced apart in the circumferential direction of the electrode cavity.

[0010] Understandably, in multiple secondary channels, the electrolyte flow rate is faster in the secondary channels closer to the outlet. As the electrolyte flows further away from the outlet, the distance it travels is longer, resulting in greater pressure loss and a relatively slower flow rate in the secondary channels further from the outlet. When the electrolyte enters the electrode cavity directly through the first outlet, the following phenomenon occurs: the electrolyte flowing into the electrode cavity from the faster-flowing secondary channels diffuses more rapidly on the electrode surface, while the electrolyte flowing into the electrode cavity from the slower-flowing secondary channels diffuses more slowly on the electrode surface. Areas with slower electrolyte diffusion receive insufficient replenishment of active material, leading to concentration polarization.

[0011] Therefore, by setting up a secondary flow channel to divert the electrolyte flowing out of the outlet, and a tertiary flow channel to further divert the electrolyte flowing out of the first outlet, the flow velocity of the electrolyte entering the electrode cavity can be made more uniform. This eliminates the flow dead zone at the edge of the electrode cavity and avoids local impact from high-speed liquid flow. Furthermore, it shortens the average diffusion distance of the electrolyte from the tertiary flow channel to various positions on the electrode surface, resulting in a more uniform concentration distribution of active materials in the electrolyte. The flow battery can operate stably at a higher average current density, effectively avoiding severe concentration polarization caused by prematurely reaching the limiting current in some areas, and thus helping to improve the energy efficiency of the flow battery.

[0012] In two adjacent secondary channels, the cross-sectional area of ​​the secondary channel farther from the outlet is larger than that of the secondary channel closer to the outlet. This balances the pressure drop loss caused by the flow distance in the secondary channel farther from the outlet, ensuring that the electrolyte flow rates in the two adjacent secondary channels are basically the same.

[0013] In two adjacent tertiary channels, the cross-sectional area of ​​the tertiary channel farther from the first outlet is larger than that of the tertiary channel closer to the first outlet. This balances the pressure drop loss caused by the flow distance in the tertiary channel farther from the first outlet, making the electrolyte flow rate in the two adjacent tertiary channels basically the same.

[0014] In this way, the flow rate of the electrolyte entering the electrode cavity from the second outlet is more uniform, which shortens the average diffusion distance of the active material from the tertiary flow channel to various positions on the electrode surface. The concentration distribution of the active material in the electrolyte is more uniform, which can more effectively reduce concentration polarization and help to further improve the energy efficiency of the flow battery.

[0015] In addition, compared to adding a fourth or more flow channels to further divert the electrolyte, the pressure drop of the electrolyte flowing in the three-stage flow channel structure is not too large, which also helps to reduce the power consumption of the drive pump.

[0016] In one possible implementation of the first aspect, among multiple secondary flow channels, the secondary flow channel closest to the primary flow channel is designated as the first flow channel, and the other secondary flow channels are designated as second flow channels; the relationship between the cross-sectional area of ​​the second flow channel and the cross-sectional area of ​​the first flow channel is as follows:

[0017] S i =K 2 ·S(D) i / D) 1 / 2 ;

[0018] Among them, S i Let S be the cross-sectional area of ​​the second flow channel, S be the cross-sectional area of ​​the first flow channel, and D be the distance between the first inlet and the outlet of the first flow channel; D i denoted as , where is the distance between the first inlet and the outlet of the second flow channel; K is a constant.

[0019] It is understandable that, compared to the first flow channel, the greater the pressure drop loss of the electrolyte in the second flow channel, which is farther from the outlet, the less electrolyte flows in the second flow channel per unit time.

[0020] Based on the relationship between the cross-sectional area of ​​the second flow channel and the cross-sectional area of ​​the first flow channel, it can be seen that, relative to the first flow channel, when the distance D between the second flow channel and the first inlet and outlet is... i When the size is larger, the cross-sectional area S of the second flow channel... i The larger the electrolyte level, the more it can balance the pressure drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the second channel per unit time, making the amount of electrolyte flowing in each secondary channel per unit time approximately equal, reducing the concentration polarization of the electrolyte on the electrode, and thus improving the energy efficiency of the flow battery.

[0021] In one possible implementation of the first aspect, the cross-sectional shape of both the primary and secondary flow channels is square, and the relationship between the side length of the cross-section of the second flow channel and the side length of the cross-section of the first flow channel is as follows:

[0022] L i =K·L(Di / D) 1 / 4 ;

[0023] Among them, L i L is the side length of the cross-section of the second flow channel, and L is the side length of the cross-section of the first flow channel.

[0024] From the relationship between the side length of the cross-section of the second flow channel and the side length of the cross-section of the first flow channel, it can be seen that, relative to the first flow channel, when the distance D between the first inlet and the outlet of the second flow channel... i When the size is larger, the side length L of the cross-section of the second flow channel is... i The larger the cross-sectional area Si of the second flow channel, the more it can balance the pressure drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the second flow channel per unit time, making the amount of electrolyte flowing in each second flow channel approximately equal per unit time, reducing the concentration polarization of the electrolyte on the electrode, and thus improving the energy efficiency of the flow battery.

[0025] In addition, the cross-sectional shape of both the primary and secondary flow channels is square, which makes it easier to process both primary and secondary flow channels. Furthermore, the secondary flow channel does not penetrate both the first and second surfaces of the electrode plate frame at the same time, which also avoids the secondary flow channel occupying too much of the frame area, thereby ensuring the structural strength of the electrode plate frame.

[0026] In one possible implementation of the first aspect, among the multiple tertiary channels connected to the secondary channel, the tertiary channel closest to the secondary channel is designated as the third channel, and the others are designated as fourth channels. The cross-sectional area of ​​the fourth channel is related to that of the third channel as follows:

[0027] Q i =K 2 ·Q(W) i / W) 1 / 2 ;

[0028] Among them, Q i Let Q be the cross-sectional area of ​​the fourth flow channel, Q be the cross-sectional area of ​​the third flow channel, and W be the distance between the second inlet and the second outlet of the third flow channel; W i denoted as , where is the distance between the second inlet and the second outlet of the fourth flow channel; K is a constant.

[0029] From the relationship between the cross-sectional area of ​​the fourth flow channel and the cross-sectional area of ​​the third flow channel, it can be seen that, relative to the third flow channel, when the distance W between the second inlet and the first outlet of the fourth flow channel... i When the size is larger, the cross-sectional area Q of the fourth flow channel... iThe larger the electrolyte level, the more it can balance the pressure drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the fourth channel per unit time, making the amount of electrolyte flowing in each of the three-stage channels approximately equal per unit time. This reduces the concentration polarization of the electrolyte on the electrodes, thereby improving the energy efficiency of the flow battery.

[0030] In one possible implementation of the first aspect, the cross-sectional shapes of both the secondary and tertiary flow channels are square, and the relationship between the side length of the fourth flow channel's cross-section and the side length of the third flow channel's cross-section is as follows:

[0031] R i =K·R(W) i / W) 1 / 4 ;

[0032] Among them, R i R is the side length of the cross-section of the fourth flow channel, and R is the side length of the cross-section of the third flow channel.

[0033] From the relationship between the side length of the cross-section of the fourth flow channel and the side length of the cross-section of the third flow channel, it can be seen that, relative to the third flow channel, when the distance W between the second inlet and the first outlet... i When the size is larger, the side length R of the cross-section of the fourth flow channel is... i The larger the cross-sectional area Q of the fourth flow channel, the better. i The larger the electrolyte level, the more it can balance the pressure drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the fourth channel per unit time, making the amount of electrolyte flowing in each of the three-stage channels approximately equal per unit time. This reduces the concentration polarization of the electrolyte on the electrodes, thereby improving the energy efficiency of the flow battery.

[0034] In addition, the cross-sectional shape of the secondary and tertiary flow channels is square, which makes the secondary and tertiary flow channels easier to process. Furthermore, the tertiary flow channel does not penetrate the first and second surfaces of the electrode plate frame at the same time, which also avoids the tertiary flow channel occupying too much of the frame area, thus ensuring the structural strength of the electrode plate frame.

[0035] In one possible implementation of the first aspect, the value of K ranges from 0.98 to 1.18. It is understandable that, given a fixed electrode plate frame size, when the value of K is too large, the calculated cross-sectional areas of the second and fourth flow channels are larger, meaning the dimensions of the second and fourth flow channels are larger, which affects the structural strength of the electrode plate frame. Conversely, when the value of K is too small, the calculated cross-sectional areas of the second and fourth flow channels are smaller, making it difficult to adequately balance the pressure drop losses within the second and fourth flow channels and effectively reduce the concentration polarization of the electrolyte on the electrode surface.

[0036] By setting K to a value ranging from 0.98 to 1.18, the second and fourth flow channels have suitable cross-sectional areas. When the cross-sections of the second and fourth flow channels are both square, the side lengths of the second and fourth flow channels are not too large, thus ensuring the structural strength of the electrode plate frame. Furthermore, this can better balance the pressure drop loss in the second and fourth flow channels, effectively reduce the degree of concentration polarization of the electrolyte on the electrode surface, and help improve the energy efficiency of the flow battery.

[0037] In one possible implementation of the first aspect, the number of secondary channels is 4 to 6. It should be noted that when the number of secondary channels is too large, the pressure drop of the electrolyte is too large, resulting in excessive power consumption of the driving pump. From a practical application perspective, this is equivalent to increasing the energy consumption of the flow battery. On the other hand, when the number of secondary channels is too small, it is difficult to reduce concentration polarization and achieve the function of rapidly removing by-reaction products.

[0038] Therefore, by using four to six secondary flow channels, in addition to reducing concentration polarization and rapidly removing by-reaction products, it also helps to reduce the power consumption of the drive pump.

[0039] In one possible implementation of the first aspect, the number of secondary channels is even, and the multiple secondary channels are symmetrically distributed on opposite sides of the extension direction of the primary channel, which can make the flow rate of the electrolyte in the multiple secondary channels more uniform.

[0040] In one possible implementation of the first aspect, the number of tertiary channels connected to each secondary channel is 4 to 8. It should be understood that when the number of tertiary channels is too large, the pressure drop of the electrolyte is too large, resulting in excessive power consumption of the driving pump. From a practical application perspective, this is equivalent to increasing the energy consumption of the flow battery. On the other hand, when the number of tertiary channels is too small, it is difficult to reduce concentration polarization and achieve the function of quickly removing by-reaction products.

[0041] Therefore, the number of tertiary channels connected through each secondary channel is 4 to 8. In addition to reducing concentration polarization and quickly removing by-reaction products, this also helps to reduce the power consumption of the drive pump.

[0042] In one possible implementation of the first aspect, the number of tertiary channels connected to each secondary channel is even, and the multiple tertiary channels are symmetrically distributed on opposite sides of the extension direction of the secondary channels, which can make the flow rate of the electrolyte in the multiple tertiary channels more uniform.

[0043] In one possible implementation of the first aspect, there are two flow channel structures, symmetrically distributed on opposite sides of the electrode cavity. The two flow channel structures are an inflow channel and an outflow channel, each including the aforementioned primary, secondary, and tertiary flow channels, and are symmetrically distributed on opposite sides of the electrode cavity. This ensures that the electrolyte must pass through the electrode cavity to flow out, thereby guaranteeing sufficient contact between the electrolyte and the electrode, allowing for a full reaction of the electrolyte on the electrode, which is beneficial for increasing the energy efficiency of the flow battery.

[0044] By setting up an outflow channel, byproducts of electrolyte reactions can be discharged from the electrode plate frame through the outflow channel. In other words, the outflow channel can efficiently remove byproducts of active materials, such as hydrogen gas produced by the hydrogen evolution reaction commonly seen in flow batteries. This ensures that byproducts flow out of the electrode cavity quickly and in a timely manner, greatly reducing the residence time and coverage area of ​​products on the electrode surface and ensuring the activity of the electrode surface. It can also avoid the depletion of active materials and product accumulation caused by local flow stagnation, and prevent byproduct accumulation from hindering electrolyte flow. This minimizes the negative impact of byproducts on the flow battery and maintains a uniform distribution of active material concentration throughout the electrode cavity.

[0045] By setting inflow and outflow channels on opposite sides of the electrode cavity, the mass transfer process can be optimized by enhancing the supply of active materials and the removal of products. This can minimize concentration polarization on the electrode surface, improve current density and its uniformity, reduce the negative impact of side reactions, and help improve the energy efficiency of flow batteries.

[0046] Secondly, a flow battery is provided, comprising the electrode plate frame of the flow battery provided in the first aspect. It is understood that the beneficial effects achievable by the flow battery described in the second aspect can be referenced to the beneficial effects in the first aspect and any possible implementation thereof, and will not be repeated here. Attached Figure Description

[0047] Figure 1 A schematic diagram illustrating the working principle of a flow battery provided for some embodiments of this application;

[0048] Figure 2 This application provides a partial structural schematic diagram of a flow battery according to some embodiments;

[0049] Figure 3 This application provides a schematic diagram of the structure of an electrode plate frame according to some embodiments;

[0050] Figure 4 for Figure 3 Enlarged view of the circled area at point A;

[0051] Figure 5 for Figure 3 Enlarged view of the circled area at point B.

[0052] Figure label:

[0053] 100. Flow battery;

[0054] 10. Electrode plate frame; 10a. Positive electrode plate frame; 10b. Negative electrode plate frame; 1. Frame body; 11. Electrode cavity; S1. First direction;

[0055] 2. Flow channel structure; 2a. Inflow channel; 2b. Outflow channel; 21. Primary flow channel; 211. Outlet; 22. Secondary flow channel; 221. First inlet; 222. First outlet; 223. First flow channel; 224. Second flow channel; 23. Tertiary flow channel; 231. Second inlet; 232. Second outlet; 233. Third flow channel; 234. Fourth flow channel; 24. First branch; 241. First sub-branch; 242. Second sub-branch; 25. Second branch; 251. Third sub-branch; 252. Fourth sub-branch;

[0056] 3. Positive electrode; 4. Negative electrode; 5. Ion exchange membrane; 6. Bipolar plate; 7. First storage tank; 70. Positive electrolyte; 8. Second storage tank; 80. Negative electrolyte; 9. Battery stack; 90. Drive pump; 901. First drive pump. Detailed Implementation

[0057] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0058] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0059] To facilitate understanding, before providing a detailed description of the flow battery in the embodiments of this application, the relevant terms involved in the embodiments of this application will be explained first.

[0060] Energy efficiency: This is a key indicator that measures the energy utilization efficiency of a battery during charge and discharge cycles. It is determined by both coulombic efficiency and voltage efficiency.

[0061] Concentration polarization refers to the phenomenon in which, during an electrode reaction, the diffusion rate of reactants or products is lower than the electrochemical reaction rate, resulting in a concentration gradient between the solution near the electrode surface and the bulk solution, which in turn causes the electrode potential to deviate from the equilibrium value.

[0062] Pressure drop: refers to the decrease in pressure caused by energy loss during the flow of a fluid.

[0063] With economic development, the demand for energy is increasing, and the environmental problems caused by the massive consumption of fossil fuels are becoming increasingly prominent. Large-scale utilization of renewable energy and achieving energy diversification have become important strategies for energy security and sustainable development for countries worldwide. However, the discontinuity and instability of renewable energy sources such as wind and solar power make direct utilization difficult. Therefore, utilizing energy storage technology to achieve a continuous supply of renewable energy is key to solving these problems. Flow batteries, due to their flexible design, high safety, and long cycle life, have become one of the most promising technologies in the large-scale, long-term energy storage market. Flow batteries are not only used for energy storage in renewable energy generation from wind and solar power, but also for emergency power systems, backup power stations, and peak shaving and valley filling in power systems.

[0064] Reference Figure 1 , Figure 1 This is a schematic diagram illustrating the working principle of a flow battery 100 provided in some embodiments of this application. The flow battery 100 typically includes an electrolyte and a battery stack 9. The battery stack 9 can convert electrical energy into chemical energy and store it in the electrolyte. When needed, the chemical energy in the electrolyte can be converted back into electrical energy and released to a power source or external load. The battery stack 9 can be assembled from multiple battery cells by stacking them.

[0065] Reference Figure 1 and Figure 2 , Figure 2 This is a partial structural schematic diagram of a flow battery provided in some embodiments of this application; the battery cell may include electrodes and an ion exchange membrane 5. The electrodes serve as sites for redox reactions of active substances (such as iron ions, chromium ions, vanadium ions, etc.) in the electrolyte. The electrolyte includes a positive electrode electrolyte 70 and a negative electrode electrolyte 80. The electrodes may include a positive electrode 3 and a negative electrode 4, with the positive electrode 3 in contact with the positive electrode electrolyte 70 and the negative electrode 4 in contact with the negative electrode electrolyte 80. The ion exchange membrane 5 is disposed between the positive electrode 3 and the negative electrode 4.

[0066] In some embodiments, the flow battery 100 includes a first storage tank 7 and a second storage tank 8. The positive electrolyte 70 can be stored in the first storage tank 7, and the negative electrolyte 80 can be stored in the second storage tank 8. When the flow battery 100 is operating, the positive electrolyte 70 in the first storage tank 7 is transported to the battery stack 9 via a first drive pump 901, causing the positive electrode 3 to come into contact with the positive electrolyte 70. The active material in the positive electrolyte 70 undergoes a redox reaction on the positive electrode 3, thereby realizing the interconversion of chemical energy and electrical energy. Electrical energy is stored and released through the charging and discharging of the flow battery 100. Hydrogen ions, driven by the potential difference, are conducted from one side of the ion exchange membrane 5 to the other side, while the ion exchange membrane 5 blocks other ions in the positive electrolyte 70 from passing through.

[0067] It should be understood that when the flow battery 100 is working, the process of converting chemical energy into electrical energy between the negative electrode 4 and the negative electrolyte 80 can be referred to the process of converting chemical energy into electrical energy between the positive electrolyte 70 and the positive electrode 3, which will not be repeated here.

[0068] For example, the flow battery 100 can be an iron-chromium flow battery, a vanadium redox flow battery, a lithium-ion flow battery, or a lead-acid flow battery. For ease of explanation, the following description uses an iron-chromium flow battery as an example, but this should not be construed as a limitation of this application.

[0069] The positive electrode electrolyte 70 of the iron-chromium flow battery may include divalent iron ions (Fe2+). 2+ ) and ferric ions (Fe 3+ The negative electrode electrolyte 80 may include divalent chromium ions (Cr). 2+ ) and trivalent chromium ions (Cr 3+ When the flow battery 100 is charged, the Fe in the positive electrode electrolyte 70 2+ An oxidation reaction occurs at the positive electrode 3, Fe... 2+ It loses electrons at the surface of cathode 3 and transforms into Fe. 3+ Cr in negative electrode electrolyte 80 3+ A reduction reaction occurs, Cr 3+ Electrons are gained on the surface of the negative electrode 4 and it transforms into Cr. 2+ When the flow battery discharges, the Fe in the electrolyte of the positive electrode 3... 3+ A reduction reaction occurs, Fe 3+ Electrons are gained on the surface of cathode 3 and it transforms into Fe. 2+ Cr in negative electrode electrolyte 80 2+ An oxidation reaction occurs, Cr 2+ The porous electrode surface loses electrons and transforms into Cr. 3+ .

[0070] Reference Figure 1 and Figure 2 The individual cells of the flow battery 100 may also include bipolar plates 6, which are typically bonded tightly to the electrodes via a hot-pressing process. As a key component of the flow battery 100, the primary purpose of the bipolar plates 6 is to conduct current. Electrons generated by the redox reaction of the active material on the electrodes need to pass through a low-resistance path. During discharge, electrons are conducted out through this path, and during charging, electrons are introduced through the same path. Therefore, the bipolar plates 6 provide a large-area, highly conductive surface, effectively collecting and conducting the current generated at each active site on the electrodes. For example, the bipolar plates 6 can conduct current to adjacent individual cells or ultimately to the end plates at both ends of the battery stack 9.

[0071] In some embodiments, the battery cell of the flow battery 100 may further include an electrode frame 10. The electrode frame 10 includes a frame 1 with an electrode cavity 11 for accommodating electrodes. The electrode frame 10 may include a positive electrode frame 10a and a negative electrode frame 10b. The positive electrode 3 may be accommodated in the electrode cavity 11 of the positive electrode frame 10a, and the negative electrode 4 may be accommodated in the electrode cavity 11 of the negative electrode frame 10b.

[0072] In some embodiments, the electrode plate frame 10 may include opposing first and second surfaces, and the electrode cavity 11 may penetrate at least one of the first and second surfaces. For example, the electrode cavity 11 may penetrate the first surface; or, the electrode cavity 11 may penetrate the second surface; or, the electrode cavity 11 may penetrate both the first and second surfaces.

[0073] Reference Figure 1 and Figure 2 In some embodiments, the frame 1 is provided with a flow channel structure 2, which is connected to the electrode cavity 11. The flow channel structure 2 is used to supply electrolyte flow. The electrolyte can enter the electrode cavity 11 from the flow channel structure 2, so that the electrolyte and the electrode are in full contact and an oxidation-reduction reaction occurs on the electrode in the electrode cavity 11.

[0074] However, the unreasonable flow channel structure design of the electrode plate frame in related technologies leads to uneven concentration distribution of active materials in the electrolyte on the electrode surface, causing significant concentration polarization and affecting the energy efficiency of the flow battery 100. Related technologies have also optimized the flow channel structure 2 of the electrode plate frame 10 to initially reduce concentration polarization, but this results in higher power consumption for the drive pump 90 that drives the electrolyte flow.

[0075] To solve the above technical problems, refer to Figure 3 , Figure 3This application provides a schematic diagram of the structure of an electrode plate frame according to some embodiments of the present application. The present application proposes an electrode plate frame 10 for a flow battery 100. The electrode plate frame 10 includes a frame body 1, on which a flow channel structure 2 is provided. The flow channel structure 2 includes a primary flow channel 21, a secondary flow channel 22, and a tertiary flow channel 23. The secondary flow channel 22 is located on the side of the tertiary flow channel 23 away from the electrode cavity 11; the primary flow channel 21 is located on the side of the secondary flow channel 22 away from the tertiary flow channel 23. The frame body 1 also has a flow channel inlet, which communicates with the primary flow channel 21. Under the drive of the driving pump 90, the electrolyte can enter the flow channel structure 2 from the flow channel inlet.

[0076] Reference Figure 3 , Figure 4 and Figure 5 , Figure 4 for Figure 3 Enlarged view of the circled area at point A; Figure 5 for Figure 3 Enlarged view of the circled area at point B. The primary flow channel 21 has an outlet 211, the secondary flow channel 22 has a first inlet 221 and a first outlet 222, and the tertiary flow channel 23 has a second inlet 231 and a second outlet 232. The first inlet 221 is connected to the outlet 211, the second inlet 231 is connected to the first outlet 222, and the second outlet 232 is connected to the electrode cavity 11. The electrolyte entering the flow channel structure 2 can enter the electrode cavity 11 from the second inlet 231.

[0077] There are multiple secondary flow channels 22, and the multiple secondary flow channels 22 are spaced apart in the circumferential direction of the electrode cavity 11; each secondary flow channel 22 is connected to multiple tertiary flow channels 23, and the multiple tertiary flow channels 23 are spaced apart in the circumferential direction of the electrode cavity 11.

[0078] Understandably, among the multiple secondary channels 22, the electrolyte flow rate is faster in the secondary channel 22 closer to the outlet 211; the electrolyte flows to the secondary channel 22 farther from the outlet 211, where the flow distance is longer and the pressure loss is greater, thus the flow rate is relatively slower. When the electrolyte directly enters the electrode cavity 11 through the first outlet 222, the following phenomenon occurs: the electrolyte flowing into the electrode cavity 11 from the secondary channel 22 with a faster flow rate diffuses faster on the electrode surface, while the electrolyte flowing into the electrode cavity 11 from the secondary channel 22 with a slower flow rate diffuses slower on the electrode surface. In areas where the electrolyte diffusion rate is slow, the active material replenishment is insufficient, resulting in concentration polarization.

[0079] Therefore, by setting up a secondary flow channel 22 to divert the electrolyte flowing out of the outlet 211, and by setting up a tertiary flow channel 23 to further divert the electrolyte flowing out of the first outlet 222, the flow velocity of the electrolyte entering the electrode cavity 11 can be made more uniform, eliminating the flow dead zone at the edge of the electrode cavity 11 and avoiding local impact of high-speed liquid flow; and shortening the average diffusion distance of the electrolyte from the tertiary flow channel 23 to various positions on the electrode surface, the concentration distribution of active materials in the electrolyte is more uniform, and the flow battery 100 can operate stably at a higher average current density, effectively avoiding severe concentration polarization caused by premature local reaching of the limit current, which helps to improve the energy efficiency of the flow battery 100.

[0080] Reference Figure 3 In some embodiments, there can be two flow channel structures 2, namely an inflow flow channel 2a and an outflow flow channel 2b. Both the inflow flow channel 2a and the outflow flow channel 2b include the aforementioned primary flow channel 21, secondary flow channel 22, and tertiary flow channel 23, and the inflow flow channel 2a and the outflow flow channel 2b are symmetrically distributed on opposite sides of the electrode cavity 11. This ensures that the electrolyte must pass through the electrode cavity 11 to flow out, thereby guaranteeing sufficient contact between the electrolyte and the electrode, allowing the electrolyte to react fully on the electrode, which is beneficial for increasing the energy efficiency of the flow battery 100.

[0081] In some embodiments, the frame 1 may also be provided with a flow channel inlet and a flow channel outlet. The flow channel inlet is connected to the inflow flow channel 2a, and the flow channel outlet is connected to the outflow flow channel 2b. Under the drive of the drive pump 90, the electrolyte can enter the inflow flow channel 2a through the flow channel inlet, and after flowing through the electrode cavity 11 and the outflow flow channel 2b, the electrolyte flows out of the electrode plate frame 10 through the flow channel outlet.

[0082] For example, the electrode cavity 11 can be approximately rectangular, and the inflow channel 2a and the outflow channel 2b can be symmetrically distributed on opposite sides of the width direction of the electrode cavity 11. Of course, in some other embodiments, the inflow channel 2a and the outflow channel 2b can also be symmetrically distributed on opposite sides of the length direction of the electrode cavity 11. It should be noted that the aforementioned symmetrical distribution can refer to an axially symmetrical distribution or a centrally symmetrical distribution.

[0083] In some embodiments, the flow channel structure 2 may be disposed on the first surface of the frame 1; or, the flow channel structure 2 may also be disposed on the second surface of the frame 1; or, both the first and second surfaces of the frame 1 may be provided with the aforementioned flow channel structure 2.

[0084] By setting the aforementioned outflow channel 2b, the by-reaction products generated by the electrolyte can be discharged from the electrode plate frame 10 through the outflow channel 2b. That is, the outflow channel 2b can efficiently remove the by-reaction products of the active material, such as hydrogen gas generated by the hydrogen evolution reaction commonly found in flow batteries 100. This ensures that the by-reaction products flow out of the electrode cavity 11 quickly and in a timely manner, greatly reducing the residence time and coverage area of ​​the products on the electrode surface, and ensuring the activity of the electrode surface. It can also avoid the depletion of active material and product accumulation caused by local flow stagnation, and prevent the accumulation of by-reaction products from hindering the flow of electrolyte, thereby minimizing the negative impact of by-reaction products on the flow battery 100 and maintaining a uniform distribution of active material concentration throughout the electrode cavity 11.

[0085] In summary, by providing inflow channel 2a and outflow channel 2b on opposite sides of electrode cavity 11, the supply of active material and removal of products can be enhanced to optimize the mass transfer process. This can minimize concentration polarization on the electrode surface, improve current density and its uniformity, reduce the negative impact of side reactions, and help improve the energy efficiency of flow battery 100.

[0086] Reference Figure 3 , Figure 4 and Figure 5 In some embodiments, in two adjacent secondary channels 22, the cross-sectional area of ​​the secondary channel 22 farther from the outlet 211 is larger than that of the secondary channel 22 closer to the outlet 211. This can balance the pressure drop loss caused by the flow distance in the secondary channel 22 farther from the outlet 211, so that the flow rate of the electrolyte in the two adjacent secondary channels 22 is basically the same.

[0087] In two adjacent tertiary channels 23, the cross-sectional area of ​​the tertiary channel 23 farther from the first outlet 222 is larger than that of the tertiary channel 23 closer to the first outlet 222. This can balance the pressure drop loss caused by the flow distance in the tertiary channel 23 farther from the first outlet 222, so that the flow rate of the electrolyte in the two adjacent tertiary channels 23 is basically the same.

[0088] In this way, the flow rate of the electrolyte entering the electrode cavity 11 from the second outlet 232 is more uniform, which shortens the average diffusion distance of the active material from the tertiary flow channel 23 to various positions on the electrode surface. The concentration distribution of the active material in the electrolyte is more uniform, which can more effectively reduce concentration polarization and help to further improve the energy efficiency of the flow battery 100.

[0089] In addition, compared to adding a fourth or more flow channels to further divert the electrolyte, the pressure drop of the electrolyte flowing in the three-stage flow channel structure is not too large, which also helps to reduce the power consumption of the drive pump.

[0090] For example, when the distances between two secondary channels 22 and the outlet 211 are equal, the cross-sectional areas of the two secondary channels 22 are equal. Similarly, among multiple tertiary channels 23 connected to the same secondary channel 22, when the distances between two adjacent tertiary channels 23 and the first outlet 222 are equal, the cross-sectional areas of the two tertiary channels 23 are equal. It should be noted that the cross-sectional area of ​​the secondary channel 22 refers to the surface cut by a plane perpendicular to the length direction of the secondary channel 22, and the cross-sectional area of ​​the tertiary channel 23 refers to the surface cut by a plane perpendicular to the length direction of the tertiary channel 23.

[0091] Reference Figure 3 In some embodiments, the number of secondary flow channels 22 is 4 to 6, for example, 4, 5, or 6. It should be noted that when the number of secondary flow channels 22 is too large, the pressure drop of the electrolyte is too large, resulting in excessive power consumption of the drive pump 90. From a practical application perspective, this is equivalent to increasing the energy consumption of the flow battery 100. On the other hand, when the number of secondary flow channels 22 is too small, it is difficult to reduce concentration polarization and achieve the function of rapidly discharging by-reaction products.

[0092] The number of secondary flow channels 22 is 4 to 6, which not only reduces concentration polarization and quickly removes by-reaction products, but also helps to reduce the power consumption of the drive pump 90.

[0093] When the number of secondary channels 22 is even, the number of secondary channels 22 can be 4 or 6, and the multiple secondary channels 22 are symmetrically distributed on opposite sides of the extension direction of the primary channel 21, which can make the flow rate of electrolyte in the multiple secondary channels 22 more uniform.

[0094] For example, there may be one primary flow channel 21. In some other embodiments, there may also be multiple primary flow channels 21, where "multiple" means two or more.

[0095] Reference Figure 3 In some embodiments, each secondary flow channel 22 is connected to 4 to 8 tertiary flow channels 23, for example, each secondary flow channel 22 is connected to 4, 5, 6, 7, or 8 tertiary flow channels 23. It should be understood that when the number of tertiary flow channels 23 is too large, the pressure drop of the electrolyte is too large, resulting in excessive power consumption of the driving pump 90. From a practical application perspective, this is equivalent to increasing the energy consumption of the flow battery 100. On the other hand, when the number of tertiary flow channels 23 is too small, it is difficult to reduce concentration polarization and achieve the function of quickly removing by-reaction products.

[0096] The number of tertiary channels 23 connected through each secondary channel 22 is 4 to 8. In addition to reducing concentration polarization and quickly removing side reaction products, it also helps to reduce the power consumption of the drive pump 90.

[0097] When the number of tertiary channels 23 connected to each secondary channel 22 is even, the number of tertiary channels 23 connected to each secondary channel 22 is 4, 6 or 8, and the multiple tertiary channels 23 are symmetrically distributed on opposite sides of the extension direction of the secondary channel 22, which can make the flow rate of electrolyte in the multiple tertiary channels 23 more uniform.

[0098] In summary, the number of secondary channels 22 is 4 to 6, and the number of tertiary channels 23 connected to each secondary channel 22 is 4 to 8. This can ensure that the electrolyte is evenly distributed in the electrode cavity 11, reduce concentration polarization, and reduce voltage drop, achieving a perfect balance between the two, which helps to improve the energy efficiency of the flow battery 100.

[0099] For example, the cross-sectional area of ​​the secondary flow channel 22 is smaller than that of the primary flow channel 21, and the cross-sectional area of ​​the tertiary flow channel 23 is smaller than that of the secondary flow channel 22.

[0100] An electrochemical test experiment can be conducted on the flow battery 100 to verify the effect of different designs of the flow channel structure 2 (taking the inflow channel 2a as an example) on the energy efficiency of the flow battery 100. For example, cyclic voltammetry can be used to conduct the electrochemical test experiment on the flow battery 100.

[0101] In some embodiments, the flow battery 100 used for testing is an iron-chromium flow battery and is a single cell; the ion exchange membrane 5 is a perfluorosulfonic acid proton exchange membrane (Nafion™ NR212); the electrode material includes carbon felt; and the electrolyte includes ferrous chloride (FeCl₂) with a molar concentration of 1 mol / L. 2 ), chromium trichloride (CrCl) with a molar concentration of 1 mol / L 3 The test involved a solution of dilute hydrochloric acid (HCl) with a molar concentration of 3 mol / L. Test parameters included: a test temperature of 65℃ and an electrode area of ​​20.0 × 50.0 cm². 2 The charging and discharging current density is 100 mA / cm². 2 The charge / discharge cutoff voltage is 0.8V~1.2V.

[0102] Electrochemical testing experiment one can include multiple embodiments, each with a different number of secondary channels 22, ranging from 4 to 6. Each secondary channel 22 is connected to a different number of tertiary channels 23, ranging from 4 to 8. Electrochemical testing experiment one can also include multiple comparative examples, each with a different number of tertiary channels 23, and some comparative examples may include a quaternary channel in the channel structure 2. The number of primary channels 21 is the same in all embodiments and comparative examples; for example, each example may have only one primary channel 21.

[0103] The parameters of the flow channel structure 2 in multiple embodiments and multiple comparative examples are shown in Table 1.1, and the electrochemical test results of the flow battery 100 in multiple embodiments and multiple comparative examples are shown in Table 1.2.

[0104] Table 1.1 Parameters of the flow channel structure

[0105]

[0106] Table 1.2 Electrochemical test results of flow batteries

[0107]

[0108] As can be seen from the embodiments in Table 1.2, the flow channel structure 2 in Embodiments 1, 2, and 3 all include a primary flow channel 21, a secondary flow channel 22, and a tertiary flow channel 23. The number of secondary flow channels 22 is 4 to 6, and the number of tertiary flow channels 23 is 4 to 8. In this way, while ensuring that the power consumption of the drive pump 90 is not too high, the electrolyte can be evenly distributed in the electrode cavity 11, concentration polarization can be reduced, and the energy efficiency of the flow battery 100 can be improved. The energy efficiency of the flow battery 100 is greater than 79%.

[0109] In Comparative Example 1, the flow channel structure 2 only includes a primary flow channel 21. Due to the use of only a primary flow channel 21, the flow battery 100 exhibits high concentration polarization, ultimately resulting in low energy efficiency (below 78%). In Comparative Example 2, each secondary flow channel 22 corresponds to 10 tertiary flow channels 23, exceeding the range of 4-8 tertiary flow channels 23. This leads to significant voltage drop losses, resulting in low energy efficiency (below 78%) for the flow battery 100, and also increases the power consumption of the driving pump 90. In Comparative Example 3, the flow channel structure 2, based on the flow channel structure 2 of Example 1, adds a fourth flow channel, resulting in excessive voltage drop losses and potentially uneven concentration distribution of active materials in the electrolyte within the electrode cavity 11, leading to low energy efficiency (below 78%) for the flow battery 100.

[0110] Reference Figure 3In some embodiments, the primary flow channel 21, the secondary flow channel 22, and the tertiary flow channel 23 can be arranged sequentially along the first direction S1, and all three flow channels extend along the first direction S1. The first direction S1 can be parallel to the arrangement direction of the inflow channel 2a, the electrode cavity 11, and the outflow channel 2b.

[0111] The flow channel structure 2 may further include a first branch 24, which may be located on the side of the primary flow channel 21 near the secondary flow channel 22. The first branch 24 is connected to both the primary flow channel 21 and the secondary flow channel 22. The first branch 24 may extend along a second direction, which intersects with the first direction S1, for example, the second direction may be perpendicular to the first direction S1. The first branch 24 may include a first sub-branch 241 and a second sub-branch 242, which are located on opposite sides of the primary flow channel 21 along the second direction. The electrolyte flowing out of the outlet 211 may flow along the first sub-branch 241 and the second sub-branch 242 and flow into the secondary flow channel 22.

[0112] Reference Figure 3 and Figure 5 The flow channel structure 2 may also include a second branch 25. When there are multiple secondary flow channels 22, there may also be multiple second branches 25, and each secondary flow channel 22 may be connected to a second branch 25. The second branch 25 may be located on the side of the secondary flow channel 22 closer to the tertiary flow channel 23, and the second branch 25 is connected to both the secondary flow channel 22 and the tertiary flow channel 23. The second branch 25 may extend along a second direction and may include a third sub-branch 251 and a fourth sub-branch 252. The third sub-branch 251 and the fourth sub-branch 252 are located on opposite sides of the secondary flow channel 22 along the second direction, and the electrolyte flowing out from the second outlet 232 may flow along the third sub-branch 251 and the fourth sub-branch 252 and flow into the secondary flow channel 22.

[0113] Reference Figure 3 and Figure 4 In some embodiments, among the multiple secondary channels 22, the secondary channel 22 that is closest to the primary channel 21 is the first channel 223, and the other secondary channels 22 are the second channels 224.

[0114] It should be noted that the distance between the primary flow channel 21 and the secondary flow channel 22 indicates the distance between the geometric centroid of the outline shape of the liquid outlet 211 and the geometric centroid of the outline shape of the first inlet 221. When the outline shape of the liquid outlet 211 is a regular shape, its geometric centroid is the geometric center of the outline shape of the liquid outlet 211; when the shape of the first inlet 221 is a regular shape, its geometric centroid is the geometric center of the outline shape of the first inlet 221. For example, when the shape of the liquid outlet 211 is rectangular and the shape of the first inlet 221 is also rectangular, the distance between the liquid outlet 211 and the first inlet 221 is the distance between the geometric centers of the two rectangles.

[0115] It is understandable that, relative to the first flow channel 223, the greater the pressure drop loss of the electrolyte in the second flow channel 224, which is farther away from the outlet 211, the less electrolyte flows in the second flow channel 224 per unit time.

[0116] The relationship between the cross-sectional area of ​​the second flow channel 224 and the cross-sectional area of ​​the first flow channel 223 is as follows: S i =K 2 ·S(D) i / D) 1 / 2 , of which S i S is the cross-sectional area of ​​the second flow channel 224, S is the cross-sectional area of ​​the first flow channel 223, and D is the distance between the first inlet 221 and the outlet 211 of the first flow channel 223; D i K is the distance between the first inlet 221 and the outlet 211 of the second flow channel 224; K is a constant.

[0117] From the relationship between the cross-sectional area of ​​the second flow channel 224 and the cross-sectional area of ​​the first flow channel 223, it can be seen that, relative to the first flow channel 223, when the distance D between the second flow channel 224 and the first inlet 221 and outlet 211 is... i When the cross-sectional area S of the second flow channel 224 is larger, i The larger the electrolyte flow rate, the more it can balance the voltage drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the second flow channel 224 per unit time, making the amount of electrolyte flowing in each secondary flow channel 22 per unit time approximately equal, reducing the concentration polarization of the electrolyte on the electrode, and thus improving the energy efficiency of the flow battery 100.

[0118] In some embodiments, the cross-sectional shape of the primary flow channel 21 and the secondary flow channel 22 is square, the shape of the liquid outlet 211 can be square, the shape of the first inlet 221 can also be square, and the distance between the liquid outlet 211 and the first inlet 221 is the distance between the geometric centers of the two squares.

[0119] The relationship between the side length of the cross-section of the second flow channel 224 and the side length of the cross-section of the first flow channel 223 is as follows: L i =K·L(D i / D) 1 / 4 , where L i L is the side length of the cross-section of the second flow channel 224, and L is the side length of the cross-section of the first flow channel 223.

[0120] From the relationship between the side length of the cross-section of the second flow channel 224 and the side length of the cross-section of the first flow channel 223, it can be seen that, relative to the first flow channel 223, when the distance D between the first inlet 221 and the outlet 211 of the second flow channel 224... i When the size is larger, the side length L of the cross-section of the second flow channel 224 is... i The larger the cross-sectional area Si of the second flow channel 224, the better it can balance the pressure drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the second flow channel 224 per unit time, making the amount of electrolyte flowing in each second flow channel 224 approximately equal per unit time, reducing the concentration polarization of the electrolyte on the electrode, and thus improving the energy efficiency of the flow battery 100.

[0121] In addition, the cross-sectional shape of both the primary flow channel 21 and the secondary flow channel 22 is square, which makes it easier to process both the primary flow channel 21 and the secondary flow channel 22. Furthermore, the secondary flow channel 22 does not penetrate both the first and second surfaces of the electrode plate frame 10 at the same time, which also avoids the secondary flow channel 22 occupying too much area of ​​the frame 1, thereby ensuring the structural strength of the electrode plate frame 10.

[0122] In some other embodiments, the cross-sectional shapes of the primary flow channel 21 and the secondary flow channel 22 can also be rectangular, and the cross-sectional area Si of the secondary flow channel 22 can be adjusted by adjusting the length or width of the rectangle. The cross-sectional shapes of the primary flow channel 21 and the secondary flow channel 22 can also be circular or semi-circular, and the cross-sectional area S of the secondary flow channel 22 can be adjusted by adjusting the radius of the circle or semi-circle. i .

[0123] Reference Figure 3 and Figure 5In some embodiments, among the multiple tertiary channels 23 connected to the secondary channel 22, the tertiary channel 23 closest to the secondary channel 22 is the third channel 233, and the other tertiary channels 23 are the fourth channels 234. It should be noted that the method for determining the distance between the tertiary channel 23 and the secondary channel 22 can refer to the method for determining the distance between the primary channel 21 and the secondary channel 22 described above, and will not be repeated here. Compared to the third channel 233, the greater the pressure drop loss of the electrolyte in the fourth channel 234, which is farther from the first outlet 222, the less electrolyte flows within the fourth channel 234 per unit time.

[0124] The relationship between the cross-sectional area of ​​the fourth flow channel 234 and the cross-sectional area of ​​the third flow channel 233 is as follows: Q i =K 2 ·Q(W) i / W) 1 / 2 , where Q i Q is the cross-sectional area of ​​the fourth flow channel 234, Q is the cross-sectional area of ​​the third flow channel 233, and W is the distance between the second inlet 231 and the second outlet 232 of the third flow channel 233; W i K is the distance between the second inlet 231 and the second outlet 232 of the fourth flow channel 234; K is a constant.

[0125] From the relationship between the cross-sectional area of ​​the fourth flow channel 234 and the cross-sectional area of ​​the third flow channel 233, it can be seen that, relative to the third flow channel 233, when the distance W between the second inlet 231 and the first outlet 222 of the fourth flow channel 234... i When the size is larger, the cross-sectional area Q of the fourth flow channel 234 is... i The larger the electrolyte flow rate, the more it can balance the voltage drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the fourth flow channel 234 per unit time, making the amount of electrolyte flowing in each of the three-stage flow channels 23 approximately equal per unit time. This reduces the concentration polarization of the electrolyte on the electrodes, thereby improving the energy efficiency of the flow battery 100.

[0126] In some embodiments, the cross-sectional shape of the secondary flow channel 22 and the tertiary flow channel 23 is square, the shape of the first outlet 222 can be square, the shape of the second inlet 231 can also be square, and the distance between the first outlet 222 and the second inlet 231 is the distance between the geometric centers of the two squares.

[0127] The relationship between the side length of the cross-section of the fourth flow channel 234 and the side length of the cross-section of the third flow channel 233 is as follows: R i =K·R(W) i / W) 1 / 4 , where R iR is the side length of the cross-section of the fourth flow channel 234, and R is the side length of the cross-section of the third flow channel 233.

[0128] From the relationship between the side length of the cross-section of the fourth flow channel 234 and the side length of the cross-section of the third flow channel 233, it can be seen that, relative to the third flow channel 233, when the distance W between the second inlet 231 and the first outlet 222... i When the size is larger, the side length R of the cross-section of the fourth flow channel 234 is... i The larger the cross-sectional area Q of the fourth flow channel 234, the greater the value. i The larger the electrolyte flow rate, the more it can balance the voltage drop loss caused by the excessive flow distance of the electrolyte. This can increase the amount of electrolyte flowing in the fourth flow channel 234 per unit time, making the amount of electrolyte flowing in each of the three-stage flow channels 23 approximately equal per unit time. This reduces the concentration polarization of the electrolyte on the electrodes, thereby improving the energy efficiency of the flow battery 100.

[0129] In addition, the cross-sectional shape of the secondary flow channel 22 and the tertiary flow channel 23 is square, which makes the secondary flow channel 22 and the tertiary flow channel 23 easier to process. Furthermore, the tertiary flow channel 23 does not penetrate the first surface and the second surface of the electrode plate frame 10 at the same time, which can also prevent the tertiary flow channel 23 from occupying too much area of ​​the frame 1, so as to ensure the structural strength of the electrode plate frame 10.

[0130] In some other embodiments, the cross-sectional shape of the secondary flow channel 22 and the tertiary flow channel 23 may also be rectangular, and the cross-sectional area Q of the tertiary flow channel 23 can be adjusted by adjusting the length or width of the rectangle. i The cross-sectional shape of the secondary flow channel 22 and the tertiary flow channel 23 can also be circular or semi-circular. The cross-sectional area Q of the quaternary flow channel can be adjusted by adjusting the radius of the circle or semi-circle. i .

[0131] In some embodiments, the value of K ranges from 0.98 to 1.18. For example, K can be 0.98, 1, 1.05, 1.02, 1.05, 1.08, 1.1, 1.12, 1.14, 1.15, 1.17, or 1.18.

[0132] It is understandable that, given a fixed size of the electrode plate frame 10, when the value of K is too large, the calculated cross-sectional areas of the second flow channel 224 and the fourth flow channel 234 are larger, meaning that the dimensions of the second flow channel 224 and the fourth flow channel 234 are larger, which will affect the structural strength of the electrode plate frame 10. When the value of K is too small, the calculated cross-sectional areas of the second flow channel 224 and the fourth flow channel 234 are smaller, making it difficult to fully balance the pressure drop loss within the second flow channel 224 and the fourth flow channel 234, and making it difficult to effectively reduce the degree of concentration polarization of the electrolyte on the electrode surface.

[0133] With K ranging from 0.98 to 1.18, the second flow channel 224 and the fourth flow channel 234 have suitable cross-sectional areas. When the cross-sections of the second flow channel 224 and the fourth flow channel 234 are both square, the side lengths of the second flow channel 224 and the fourth flow channel 234 will not be too large, so as to ensure the structural strength of the electrode plate frame 10. Furthermore, this can better balance the pressure drop loss in the second flow channel 224 and the fourth flow channel 234, effectively reduce the degree of concentration polarization of the electrolyte on the electrode surface, and help improve the energy efficiency of the flow battery 100.

[0134] Electrochemical test experiment two can be performed on the flow battery 100 to verify the influence of the cross-sectional areas of the secondary flow channel 22 and the tertiary flow channel 23 on the energy efficiency of the flow battery 100. The test method and parameters of electrochemical test experiment two can be designed with reference to electrochemical test experiment one of the flow battery 100 in the above embodiments.

[0135] Electrochemical testing experiment two can include multiple examples and one comparative example. The cross-sections of the secondary flow channel 22 and the tertiary flow channel 23 in the multiple examples and the comparative example are all square. The parameters of the secondary flow channel 22 in the multiple examples and the comparative example are shown in Table 2.1, the parameters of the tertiary flow channel 23 in the multiple examples and the comparative example are shown in Table 2.2, and the electrochemical test results of the flow battery 100 in the multiple examples and the comparative example are shown in Table 2.3.

[0136] Table 2.1 Parameters of the Secondary Flow Channel

[0137]

[0138] Table 2.2 Parameters of the three-stage flow channel

[0139]

[0140] Table 2.3 Electrochemical test results of flow batteries

[0141]

[0142] Among the multiple secondary flow channels 22, the secondary flow channel 22 closest to the primary flow channel 21 is the first flow channel 223. According to Examples 4, 5, and 6 in Table 2.1, the distance between the first inlet 221 and the outlet 211 of the first flow channel 223 is 5 mm, and the side length of the cross-section of the first flow channel 223 is 2 mm. Two secondary flow channels 224 with different distances are selected from the secondary flow channels 22, and their cross-sectional side lengths are calculated. The distances between the first inlet 221 and the outlet 211 of the two secondary flow channels 224 are 15 mm and 25 mm, respectively. In Examples 4 to 6, the cross-sectional side lengths of the secondary flow channels 22 are set differently according to the different positions of the multiple secondary flow channels 22, and L... i =K·L(D i / D) 1 / 4 This effectively balances the pressure drop caused by the different positions of the multiple secondary channels 22, thereby reducing concentration polarization and resulting in higher energy efficiency of the flow battery 100, with an energy efficiency greater than 81%.

[0143] Among the multiple tertiary channels 23 connected to the secondary channel 22, the tertiary channel 23 closest to the secondary channel 22 is the third channel 233. According to Examples 4, 5, and 6 in Table 2.2, the distance between the second inlet 231 and the first outlet 222 of the third channel 233 is 0.75 mm, and the side length of the cross-section of the third channel 233 is 0.2 mm. Two fourth channels 234 with different distances are selected from the tertiary channels 23 to calculate their cross-sectional side lengths. The distances between the second inlet 231 and the first outlet 222 of the two fourth channels 234 are 1.5 mm and 3 mm, respectively. In Examples 4 to 6, the cross-sectional side lengths of the tertiary channels 23 are set differently according to the different positions of the multiple tertiary channels 23, and R... i =K·R(W) i / W) 1 / 4 This effectively balances the pressure drop caused by the different positions of the multiple tertiary channels 23, thereby reducing concentration polarization and resulting in higher energy efficiency of the flow battery 100, which is greater than 81%.

[0144] As can be seen from Tables 2.1, 2.2, and 2.3, Comparative Example 4 did not optimize the side lengths of the cross-sections of the secondary flow channel 22 and the tertiary flow channel 23. The side length of the cross-sections of multiple secondary flow channels 22 is 2 mm, and the side length of the cross-sections of multiple tertiary flow channels 23 connected to each secondary flow channel 22 is 0.2 mm. This results in different voltage drops in the secondary flow channels 22 / tertiary flow channels 23 at different locations, leading to uneven electrolyte distribution, which may in turn cause concentration polarization. Consequently, the energy efficiency of the flow battery 100 in Comparative Example 4 is low (below 81%).

[0145] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An electrode plate frame for a flow battery, characterized in that, include: A frame, wherein an electrode cavity is provided on the frame; The frame is provided with a flow channel structure, which is connected to the electrode cavity and is used for the flow of electrolyte. The flow channel structure includes a primary flow channel, a secondary flow channel, and a tertiary flow channel. The secondary flow channel is located on the side of the tertiary flow channel away from the electrode cavity. The primary flow channel is located on the side of the secondary flow channel away from the tertiary flow channel. The primary flow channel has a liquid outlet. The secondary flow channel has a first inlet and a first outlet. The tertiary flow channel has a second inlet and a second outlet. The first inlet is connected to the liquid outlet, the second inlet is connected to the first outlet, and the second outlet is connected to the electrode cavity; There are multiple secondary flow channels, and the multiple secondary flow channels are arranged at intervals in the circumferential direction of the electrode cavity. In two adjacent secondary flow channels, the cross-sectional area of ​​the secondary flow channel farther from the liquid outlet is larger than the cross-sectional area of ​​the secondary flow channel closer to the liquid outlet. Among the multiple secondary channels, the secondary channel that is closest to the primary channel is the first channel, and the others are the second channels. The relationship between the cross-sectional area of ​​the second flow channel and the cross-sectional area of ​​the first flow channel is as follows: S i =K 2 ·S(D i / D) 1 / 2 ; Among them, S i S is the cross-sectional area of ​​the second flow channel, S is the cross-sectional area of ​​the first flow channel, and D is the distance between the first inlet and the outlet of the first flow channel; D i The distance between the first inlet and the outlet of the second flow channel; Each of the secondary flow channels is connected to a plurality of the tertiary flow channels, and the plurality of tertiary flow channels are arranged circumferentially in the electrode cavity. In two adjacent tertiary flow channels, the cross-sectional area of ​​the tertiary flow channel farther from the first outlet is larger than the cross-sectional area of ​​the tertiary flow channel closer to the first outlet. Among the multiple tertiary channels connected by the secondary channel, the tertiary channel closest to the secondary channel is the third channel, and the other tertiary channels are the fourth channels; The relationship between the cross-sectional area of ​​the fourth flow channel and the cross-sectional area of ​​the third flow channel is as follows: Q i =K 2 ·Q(W i / W) 1 / 2 ; Among them, Q i Let Q be the cross-sectional area of ​​the fourth flow channel, Q be the cross-sectional area of ​​the third flow channel, and W be the distance between the second inlet and the second outlet of the third flow channel; W i The distance between the second inlet and the second outlet of the fourth flow channel; The value of K ranges from 0.98 to 1.

18.

2. The electrode plate frame of the flow battery according to claim 1, characterized in that, The cross-sectional shape of both the primary flow channel and the secondary flow channel is square. The relationship between the side length of the cross-section of the second flow channel and the side length of the cross-section of the first flow channel is as follows: L i =K·L(D i / D) 1 / 4 ; Among them, L i L is the side length of the cross-section of the second flow channel, and L is the side length of the cross-section of the first flow channel.

3. The electrode plate frame of the flow battery according to claim 1, characterized in that, The cross-sectional shape of both the secondary and tertiary flow channels is square. The relationship between the side length of the cross-section of the fourth flow channel and the side length of the cross-section of the third flow channel is as follows: R i =K·R(W i / W) 1 / 4 ; Among them, R i R is the side length of the cross-section of the fourth flow channel, and R is the side length of the cross-section of the third flow channel.

4. The electrode plate frame of the flow battery according to claim 1, characterized in that, The number of secondary channels is 4 to 6; and / or the number of secondary channels is even, and multiple secondary channels are symmetrically distributed on opposite sides of the extension direction of the primary channel.

5. The electrode plate frame of the flow battery according to any one of claims 1-4, characterized in that, The number of tertiary channels connected to each of the secondary channels is 4 to 8; and / or, the number of tertiary channels connected to each of the secondary channels is an even number, and the plurality of tertiary channels are symmetrically distributed on opposite sides of the extension direction of the secondary channels.

6. The electrode plate frame of the flow battery according to claim 1, characterized in that, There are two flow channel structures, which are symmetrically distributed on opposite sides of the electrode cavity.

7. A flow battery, characterized in that, include: The electrode plate frame of the flow battery according to any one of claims 1-6.

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