Composite electrode and flow battery
By using a composite electrode structure, the problems of increased thickness and contact resistance caused by the guide plate in flow batteries are solved, achieving uniform electrolyte distribution and improved stack efficiency, simplifying stack design and reducing costs.
Patent Information
- Application Number
- CN202423320012.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2034-12-31
AI Technical Summary
In existing flow batteries, the introduction of flow guides increases the thickness of the bipolar plates, the contact resistance between the flow guides and the electrodes, and the energy loss within the stack. Furthermore, the excessive internal flow resistance of the electrodes can easily lead to a large dead zone area in the reaction.
A composite electrode structure is adopted, including an electrode plate layer and an electrode layer. The electrode layer consists of a first edge electrode, a second edge electrode, and an electrode body. The edge electrode is thinner than the electrode body. A current shunt structure and a conductive adhesive layer are set, and the current guide plate is omitted. The combination of the edge electrode and the electrode body forms a thick and thin electrode region, which improves the uniformity of electrolyte distribution and reduces contact resistance.
It reduces electrode layer flow resistance, improves electrolyte distribution uniformity, reduces stack size and cost, simplifies stack design, avoids problems caused by flow guides, and improves stack efficiency and safety.
Smart Images
Figure CN223842886U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of energy storage battery technology, and in particular, relates to a composite electrode and a flow battery. Background Technology
[0002] Flow batteries, as a novel battery technology, have gained widespread attention due to their advantages such as high efficiency, safety and reliability, long cycle life, and flexible structural design. A flow battery stack includes components such as end plates, electrodes, bipolar plates, electrode frames, and ion exchange membranes.
[0003] Currently, directly sampling electrodes with uniform thickness presents the problem of uneven electrolyte distribution within the electrode, resulting in significant dead zones in the reaction zone near the electrolyte inlet and outlet. To address these issues, current methods primarily involve incorporating flow guides in the electrode region of the bipolar plate. These flow guides ensure complete electrode wetting while reducing dead zones. However, the introduction of flow guides increases the bipolar plate thickness, raises the contact resistance between the flow guide and the electrode, increases in-pile energy loss, and adds to the complexity of bipolar plate fabrication.
[0004] There is an urgent need for an electrode that can achieve uniform electrolyte flow in the electrode region without the need for a flow guide plate, while also reducing the contact resistance between the electrode and the bipolar plate and reducing the complexity of bipolar plate fabrication. Utility Model Content
[0005] Based on the above-mentioned problems in the prior art, the purpose of this utility model embodiment is to provide a composite electrode to solve the problems in the prior art that cause the increase in the thickness of the bipolar plate, the increase in the contact resistance between the guide plate and the electrode, the increase in the energy loss in the stack, and the complexity of the bipolar plate processing technology due to the introduction of the guide plate.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is: to provide a composite electrode, comprising:
[0007] Electrode layer; and
[0008] An electrode layer is stacked on one side of the electrode layer or symmetrically stacked on both sides of the electrode layer. The electrode layer includes a first edge electrode near the electrolyte inlet on the electrode frame, a second edge electrode near the electrolyte outlet on the electrode frame, and an electrode body connecting the first edge electrode and the second edge electrode. The thickness of the first edge electrode is less than the thickness of the electrode body, and the thickness of the second edge electrode is less than the thickness of the electrode body, so that the first edge electrode, the second edge electrode, and the electrode body are joined together to form the electrode layer having a thick electrode region and a thin electrode region.
[0009] Furthermore, the first edge electrode and / or the second edge electrode are provided with a flow-diverting structure capable of dispersing the electrolyte.
[0010] Furthermore, the flow splitting structure includes a plurality of flow splitting cavities or flow splitting grooves uniformly distributed on the first edge electrode and / or the second edge electrode; or, the flow splitting structure includes a plurality of strip-shaped branch channels uniformly distributed on the first edge electrode and / or the second edge electrode.
[0011] Furthermore, the ratio of the sum of the areas of the first edge electrode and the second edge electrode to the area of the electrode body is (2-3):(7-8).
[0012] Furthermore, the thickness of the first edge electrode and / or the second edge electrode is 3 to 4.5 mm.
[0013] Furthermore, the thickness of the electrode body is 4.5–5.5 mm.
[0014] Furthermore, the composite electrode also includes a conductive adhesive layer disposed between the electrode layer and the plate layer.
[0015] Furthermore, the thickness of the conductive adhesive layer is 0.01–0.3 mm.
[0016] To achieve the above objectives, another technical solution adopted by this utility model is: providing a composite electrode, comprising:
[0017] Electrode layer; and
[0018] An electrode layer is stacked on one side of the electrode plate layer or symmetrically stacked on both sides of the electrode plate layer. The electrode layer includes an electrode body, a first edge electrode near the electrolyte inlet on the electrode frame, and two second edge electrodes near the electrolyte outlet on the electrode frame. The first edge electrode is located on the side of the electrode body near the electrolyte inlet, and the two second edge electrodes are respectively located at two corners of the electrode body near the electrolyte outlet. The thickness of the first edge electrode is less than the thickness of the electrode body, and the thickness of the second edge electrode is less than the thickness of the electrode body, so that the first edge electrode, the two second edge electrodes, and the electrode body are joined together to form a rectangular electrode layer with a thick electrode region and a thin electrode region.
[0019] Another objective of this utility model embodiment is to provide a flow battery to solve the problem in the prior art where excessive internal flow resistance of the electrodes easily leads to a large reaction dead zone area at the electrode edge.
[0020] To achieve the above objectives, the technical solution adopted by this utility model is to provide a flow battery, including the composite electrode provided in any of the above embodiments.
[0021] Compared with the prior art, one or more technical solutions in the embodiments of this utility model have at least one of the following beneficial effects:
[0022] The composite electrode provided by this invention can significantly reduce the flow resistance of the first and second edge electrodes, reduce the dead zone area of the electrode layer near the electrolyte inlet and outlet, and improve the uniformity of electrolyte distribution within the electrode layer. Furthermore, the reduced flow resistance of the first and second edge electrodes also reduces the flow resistance encountered by the electrolyte during its flow within the electrode layer, increasing the uniformity of electrolyte flow and reducing losses caused by flow resistance. In addition, the electrode layer is directly disposed on the electrode plate layer, eliminating the need for a flow guide plate on the bipolar plate. This avoids the problems caused by the introduction of a flow guide plate, such as increased bipolar plate thickness, increased contact resistance between the flow guide plate and the electrode, increased energy loss within the stack, and increased complexity of the bipolar plate manufacturing process. This reduces the size of the fuel cell stack, lowers its cost, and improves its efficiency.
[0023] The composite electrode provided by this utility model has a flow-dividing structure on the first edge electrode and the second edge electrode, which can disperse the electrolyte. The flow-dividing structure can divert and disperse the electrolyte flowing through the first edge electrode and the second edge electrode, thereby further improving the uniformity of electrolyte fluid distribution.
[0024] The composite electrode provided by this invention also includes a conductive adhesive layer, which not only significantly reduces the contact resistance between the electrode layer and the plate layer, but also ensures that the contact area between the electrode layer (formed by splicing thin and thick electrodes, with both thick and thin electrode regions) and the plate layer maintains a consistent resistance value. This effectively avoids localized overheating during the charging and discharging process of the fuel cell stack, while ensuring that the contact resistance between the electrode layer and the plate layer is not affected by electrode layer compression. Furthermore, the thickness of the conductive adhesive layer is much smaller than that of existing current guide plates; therefore, by omitting the current guide plate, the overall size of the fuel cell stack can be reduced.
[0025] The composite electrode provided by this invention can solve the problems caused by the guide plate, while also simplifying the design of the flow channel on the external electrode frame and reducing the cost of the external electrode frame. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 A three-dimensional structural schematic diagram of the composite electrode provided in Embodiment 1 of this utility model;
[0028] Figure 2 This is a top view of the composite electrode provided in Embodiment 1 of the present invention.
[0029] Figure 3 An exploded view of the composite electrode provided in Embodiment 1 of this utility model;
[0030] Figure 4 A three-dimensional structural schematic diagram of the composite electrode provided in Embodiment 2 of this utility model;
[0031] Figure 5 This is a top view of the composite electrode provided in Embodiment 2 of the present invention.
[0032] Figure 6 This is an exploded view of the composite electrode provided in Embodiment 2 of this utility model.
[0033] Figure 7(a) is a flow field distribution diagram of the composite electrode provided in Embodiment 3 of this utility model;
[0034] Figure 7(b) is a flow field distribution diagram of the electrode provided in Comparative Example 1 of this utility model;
[0035] Figure 8(a) is a flow field distribution diagram of the composite electrode provided in Embodiment 4 of this utility model;
[0036] Figure 8(b) is a flow field distribution diagram of the electrode provided in Comparative Example 2 of this utility model;
[0037] Figure 9 A comparison diagram of the contact resistance of the composite electrode provided in Embodiment 5 of this utility model.
[0038] The following are the labeling elements in the figure:
[0039] 1-Electrode layer;
[0040] 2-Electrode layer; 21-First edge electrode; 22-Second edge electrode; 23-Electrode body;
[0041] 3-Conductive adhesive layer; 4-Shunting cavity; 5-First step; 6-Second step. Detailed Implementation
[0042] To make the technical problems, technical solutions, and 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.
[0043] It should be noted that when an element is referred to as "connected to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to or indirectly connected to the other element. Furthermore, 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 indicated technical features. Thus, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0044] 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.
[0045] Example 1
[0046] Please refer to the following: Figures 1 to 3The composite electrode provided in Embodiment 1 of this utility model will now be described. The composite electrode in Embodiment 1 includes an electrode layer 1 and electrode layers 2 disposed on one side of the electrode layer 1 or symmetrically disposed on both sides of the electrode layer 1. The electrode layers 2 are stacked on the electrode layer 1. The electrode frame of the flow battery has a receiving cavity, in which the electrode layer 1 can be received. The electrode frame has an electrolyte inlet and an electrolyte outlet. The electrode layer 2 includes a first edge electrode 21 near the electrolyte inlet, a second edge electrode 22 near the electrolyte outlet, and an electrode body 23 connecting the first edge electrode 21 and the second edge electrode 22. Preferably, the first edge electrode 21, the electrode body 23, and the second edge electrode 22 are arranged sequentially on the electrode layer 1 along the flow direction of the electrolyte inside the electrode layer 2. The thickness of the first edge electrode 21 is less than the thickness of the electrode body 23, so that a first step 5 is formed at the connection between the first edge electrode 21 and the electrode body 23. The thickness of the second edge electrode 22 is less than the thickness of the electrode body 23, so that a second step 6 is formed at the connection between the second edge electrode 22 and the electrode body 23. During the charging and discharging of the flow battery, the electrolyte flows sequentially from the electrolyte inlet on the electrode frame to the first edge electrode 21 of the electrode layer 2, the electrode body 23 of the electrode layer 2, and the second edge electrode 22 of the electrode layer 2, and finally flows to the electrolyte outlet via the second edge electrode 22. Since the electrode body 23 is connected between the first edge electrode 21 and the second edge electrode 22, the thickness of the first edge electrode 21 is less than the thickness of the electrode body 23, and the thickness of the second edge electrode 22 is less than the thickness of the electrode body 23. This allows the thinner first edge electrode 21, the thinner second edge electrode 22, and the thicker electrode body 23 to be joined together to form an electrode layer 2 with thick and thin electrode regions. This enables the orderly combination and splicing of electrodes of different thicknesses to form an electrode layer 2 with thick and thin electrode regions. The electrode body 23 has a thinner first edge electrode 21 on the side corresponding to the electrolyte inlet on the electrode frame, and a thinner second edge electrode 22 on the side corresponding to the electrolyte outlet on the electrode frame. This can significantly reduce the flow resistance of the first edge electrode 21 and the second edge electrode 22, reduce the dead zone area of the electrode layer 2 near the electrolyte inlet and outlet, and improve the uniformity of electrolyte distribution inside the electrode layer 2. Furthermore, the reduced flow resistance of the first edge electrode 21 and the second edge electrode 22 can also reduce the flow resistance encountered by the electrolyte during its flow inside the electrode layer 2, thereby reducing the loss caused by the flow resistance.
[0047] Compared with the prior art, the composite electrode provided in this embodiment of the utility model includes an electrode layer 1 and an electrode layer 2 stacked on the electrode layer 1. The electrode layer 1 can serve as a bipolar plate in an existing fuel cell stack, and the electrode layer 2 serves as an electrode in an existing fuel cell stack. The electrode layer 2 includes a first edge electrode 21 near the electrolyte inlet, a second edge electrode 22 near the electrolyte outlet, and an electrode body 23 connecting the first edge electrode 21 and the second edge electrode 22. Since the thicker electrode body 23 is connected between the thinner first edge electrode 21 and the thinner second edge electrode 22, electrodes of different thicknesses can be orderly combined and spliced to form an electrode layer 2 with thick electrode regions and thin electrode regions. This can significantly reduce the flow resistance of the first edge electrode 21 and the second edge electrode 22, reduce the dead zone area of the electrode layer 2 near the electrolyte inlet and outlet, and improve the uniformity of electrolyte distribution inside the electrode layer 2. Furthermore, the reduced flow resistance of the first edge electrode 21 and the second edge electrode 22 also reduces the flow resistance encountered by the electrolyte during its overall flow within the electrode layer 2, increasing the uniformity of electrolyte flow and reducing losses caused by flow resistance. In addition, the electrode layer 2 is directly disposed on the electrode plate layer 1, eliminating the need for a flow guide plate on the bipolar plate. This avoids the problems caused by the introduction of a flow guide plate, such as increased thickness of the bipolar plate, increased contact resistance between the flow guide plate and the electrode, increased energy loss within the stack, and increased complexity of the bipolar plate manufacturing process. This reduces the size of the stack, lowers the cost of the stack, and improves the efficiency of the stack.
[0048] Figure 1 and Figure 3 An example is shown where an electrode layer 2 is provided on one side of the electrode layer 1. An electrode layer 2 can also be provided on the other side of the electrode layer 1. The two electrode layers 2 are arranged symmetrically and have the same structure.
[0049] In some embodiments, the first edge electrode 21 is provided with a diversion structure that can disperse the electrolyte. The diversion structure diverts and disperses the electrolyte flowing through the first edge electrode 21. On the one hand, it can ensure that the electrolyte fluid can be evenly distributed throughout the interior of the first edge electrode 21, further reducing the area of the dead zone at the edge of the electrode layer 2. On the other hand, it can make the electrolyte inside the first edge electrode 21 flow more dispersedly to the electrode body 23, thereby improving the uniformity of the electrolyte fluid distribution inside the electrode body 23.
[0050] In some embodiments, the second edge electrode 22 is provided with a diversion structure that can disperse the electrolyte. By diverting and dispersing the electrolyte flowing through the second edge electrode 22 through the diversion structure, it can be ensured that the electrolyte fluid can be evenly distributed throughout the interior of the second edge electrode 22, further reducing the area of the dead zone at the edge of the electrode layer 2.
[0051] Please refer to the following: Figure 1and Figure 2 In some embodiments, the flow-dividing structure may consist only of multiple flow-dividing cavities 4 or flow-dividing grooves uniformly distributed on the first edge electrode 21, or it may consist only of multiple flow-dividing cavities 4 or flow-dividing grooves uniformly distributed on the second edge electrode 22. Alternatively, the flow-dividing structure may include multiple flow-dividing cavities 4 or flow-dividing grooves uniformly distributed on both the first and second edge electrodes 22. That is, multiple flow-dividing cavities 4 or flow-dividing grooves may be provided only on the first edge electrode 21, only on the second edge electrode 22, or on both the first and second edge electrodes 21 and 22. Understandably, in other embodiments, the flow-dividing cavities 4 or flow-dividing grooves may be replaced by similar flow-dividing structures such as strip-shaped branch channels. The shunt cavity 4 or shunt channel can be opened on the side where the electrode layer 2 is connected to the electrode plate layer 1, or it can be opened on the side where the electrode layer 2 is opposite to the electrode plate layer 1 and extend to the side where the electrode layer 2 is connected to the electrode plate layer 1. The shunt cavity 4 or shunt channel is parallel to the first step 5 and the second step 6.
[0052] In some embodiments, the ratio of the sum of the areas of the first edge electrode 21 and the second edge electrode 22 to the area of the electrode body 23 is (2-3):(7-8). This effectively reduces the flow resistance encountered by the electrolyte during its flow within the electrode layer 2, significantly improves the uniformity of electrolyte distribution within the electrode layer 2, effectively reduces or even eliminates the reaction dead zone within the electrode layer 2, and significantly reduces the area of the dead zone at the edge of the electrode layer 2. When the ratio of the sum of the areas of the first edge electrode 21 and the second edge electrode 22 to the area of the electrode body 23 is greater than (2-3):(7-8), the areas of the thinner first edge electrode 21 and the thinner second edge electrode 22 become too large, which may exceed the range of the dead zone at the edge, thus hindering the improvement of the electrolyte flow uniformity in the edge region. When the ratio of the sum of the areas of the first edge electrode 21 and the second edge electrode 22 to the area of the electrode body 23 is less than (2-3): (7-8), the areas of the thinner first edge electrode 21 and the thinner second edge electrode 22 are too small, which is not conducive to reducing the area of the dead zone at the edge of the electrode layer 2.
[0053] In some embodiments, the thickness of the first edge electrode 21 and / or the second edge electrode 22 is 3–4.5 mm. This allows for a suitable flow resistance within the first edge electrode 21 and / or the second edge electrode 22, ensuring that the electrolyte within the first edge electrode 21 and / or the second edge electrode 22 is uniformly distributed throughout the entire first edge electrode 21 and / or the second edge electrode 22 under the influence of this flow resistance, thereby reducing the area of the dead zone at the edge of the electrode layer 2. It should be noted that the thickness of the first edge electrode 21 and the second edge electrode 22 can be the same, or the thicknesses of the first edge electrode 21 and the second edge electrode 22 can be different.
[0054] In some embodiments, the thickness of the electrode body 23 is 4.5 to 5.5 mm, so that the electrode body 23 maintains a suitable flow resistance, ensuring that the electrolyte inside the electrode body 23 can be evenly distributed throughout the entire electrode body 23 under the action of the flow resistance. This not only helps to improve the uniformity of electrolyte distribution inside the electrode layer 2, but also effectively reduces or even eliminates the reaction dead zone inside the electrode layer 2.
[0055] Please refer to the following: Figure 1 and Figure 3 In some embodiments, the composite electrode further includes a conductive adhesive layer 3 disposed between the electrode layer 2 and the electrode plate layer 1. The electrode layer 2 is bonded to the electrode plate layer 1 via the conductive adhesive layer 3 to form the composite electrode. This not only significantly reduces the contact resistance between the electrode layer 2 and the electrode plate layer 1, but also ensures that the contact area between the electrode layer 2 (which consists of thick and thin electrode regions) and the electrode plate layer 1 maintains a consistent resistance value. This effectively avoids localized overheating during the charging and discharging process of the battery stack, while ensuring that the contact resistance between the electrode layer 2 and the electrode plate layer 1 is not affected by the compression of the electrode layer 2. It should be noted that the electrode plate layer 1 can be a flexible graphite bipolar plate or a carbon-plastic bipolar plate. The thickness of the conductive adhesive layer 3 is 0.01–0.3 mm, and the raw materials used in the conductive adhesive layer 3 include the following components by weight: 30–36 parts conductive agent, 18–26 parts polymer resin, 0–6 parts dispersant, and 40 parts solvent. The conductive agent, polymer resin, and dispersant are mixed and dry-blended, and a solvent is added to homogenize the mixture to obtain a slurry. The slurry is then uniformly coated onto the surface of the electrode layer 1 using a film-forming device to prepare the conductive adhesive layer 3. Furthermore, the thickness of the conductive adhesive layer 3 is much smaller than that of existing flow guide plates. Therefore, by omitting the flow guide plate, this application can also reduce the overall size of the fuel cell stack.
[0056] Example 2
[0057] Please refer to the following: Figures 4 to 6The composite electrode provided in Embodiment 2 of this utility model will now be described. The structure of the composite electrode provided in Embodiment 2 of this utility model is basically the same as that of the composite electrode provided in Embodiment 1 of this utility model. The difference between the composite electrode structure provided in Embodiment 2 of this utility model and the composite electrode structure provided in Embodiment 1 of this utility model is that the electrode layer 2 includes an electrode body 23, a first edge electrode 21 near the electrolyte inlet on the electrode frame, and two second edge electrodes 22 near the electrolyte outlet on the electrode frame. The first edge electrode 21 is located on the side of the electrode body 23 near the electrolyte inlet, and the two second edge electrodes 22 are respectively located at two corners of the electrode body 23 near the electrolyte outlet. The thickness of the first edge electrode 21 is less than the thickness of the electrode body 23, and the thickness of the second edge electrode 22 is less than the thickness of the electrode body 23, so that the first edge electrode 21, the two second edge electrodes 22 and the electrode body 23 are spliced together to form a rectangular electrode layer 2 with a thick electrode region and a thin electrode region. During the charging and discharging of the flow battery, the electrolyte flows through the electrolyte inlet on the electrode frame to the first edge electrode 21, the electrode body 23, and the two second edge electrodes 22 of the electrode layer 2. Since the thicker electrode body 23 connects the thinner first edge electrode 21 and the two thinner second edge electrodes 22, the orderly combination and splicing of electrodes of different thicknesses to form a rectangular electrode layer 2 with both thick and thin electrode regions reduces the flow resistance of the electrolyte within the electrode layer 2. This not only improves the uniformity of electrolyte distribution within the electrode layer 2 but also effectively reduces or even eliminates the reaction dead zones within the electrode layer 2. Simultaneously, the thinner first edge electrode 21 is located on the side of the electrode body 23 corresponding to the electrolyte inlet on the electrode frame, and the thinner second edge electrodes 22 are located at the two corners of the electrode body 23 corresponding to the electrolyte outlet on the electrode frame, significantly reducing the dead zone area at the edges and corners of the electrode layer 2.
[0058] Example 3
[0059] The structure shown in Example 2 is adopted, wherein the electrode layer is a flexible graphite bipolar plate with a size of 30cm×20cm×0.6mm.
[0060] The conductive adhesive layer is composed of (by weight percentage): 20% conductive carbon black (Super P); 15% conductive carbon black (Kejtien Black); 1% carbon nanotubes (CNT); 24% polyvinylidene fluoride (PVDF); and 40% N-methylpyrrolidone (NMP).
[0061] The first edge electrode measures 30cm × 2cm × 4.5mm; it has two hollowed-out shunt cavities, each 12cm long and 0.2cm wide, with a distance of 0.1cm from the outer edge of the first edge electrode.
[0062] The two second edge electrodes are pentagonal, identical in size, and 4.5 mm thick. The five sides are, in order, the first side, the second side, the third side, the fourth side, and the fifth side. The length of the first side of the second edge electrode near the electrolyte outlet on the electrode frame is 13 cm, the length of the third side parallel to the first side is 10 cm, the length of the second side perpendicular to the first and third sides is 3 cm, the length of the fourth side is 3.9 cm, and the length of the fifth side is 0.94 cm.
[0063] The electrode layer is the same size as the electrode plate layer, and except for the first edge electrode and the second edge electrode, it is the electrode body with a thickness of 5.5 mm.
[0064] The first edge electrode 21, the electrode body 23, and the second edge electrode 22 are made of carbon felt.
[0065] A conductive adhesive layer with a thickness of 0.2 mm is applied to the surface of the electrode layer. Then, the first edge electrode, the electrode body, and the second edge electrode are spliced onto the surface of the conductive adhesive layer. After bonding and drying, a composite electrode is obtained.
[0066] Example 4
[0067] The structure shown in Example 1 is adopted, wherein the electrode layer is a flexible graphite bipolar plate with dimensions of 30cm×20cm×0.6mm.
[0068] The conductive adhesive layer is composed of (by weight percentage): 13% conductive carbon black (KS6); 15% acetylene black; 2% carbon nanotubes (CNT); 4% carboxymethyl cellulose (CMC); 26% styrene-butadiene rubber (SBR); and 40% water.
[0069] The first edge electrode measures 30cm × 2cm × 3mm; it has two hollowed-out shunt cavities, each 12cm long and 0.2cm wide, with a distance of 0.1cm from the outer edge of the first edge electrode.
[0070] The electrode body measures 30cm × 16cm × 4.5mm;
[0071] The second edge electrode measures 30cm × 2cm × 3mm and has two hollowed-out shunt cavities. The length of each shunt cavity is 12cm, the width is 0.2cm, and the distance from the outer edge of the second edge electrode is 0.1cm.
[0072] The first edge electrode, the electrode body, and the second edge electrode are all made of carbon felt.
[0073] A conductive adhesive layer with a thickness of 0.3 mm is applied to the surface of the electrode layer. Then, the first edge electrode, the electrode body, and the second edge electrode are spliced onto the surface of the conductive adhesive layer. After bonding and drying, a composite electrode is obtained.
[0074] Comparative Example 1
[0075] A 30cm×20cm×5.5mm carbon felt is used as a single electrode layer, and a 30cm×20cm×0.6mm flexible graphite plate is used as the electrode plate layer, without bonding or composite bonding.
[0076] Comparative Example 2
[0077] A 30cm×20cm×4.5mm carbon felt is used as a single electrode layer, and a 30cm×20cm×0.6mm flexible graphite plate is used as the electrode plate layer, without bonding or composite.
[0078] The flow field of electrodes prepared in Examples 3, 4, Comparative Example 1, and Comparative Example 2 with the above data was simulated using a low Reynolds number (ke) model. The results are shown in Figures 7(a), 8(a), 7(b), and 8(b), respectively. It can be seen that the composite electrode provided by this invention ensures uniform electrolyte flow and reduces edge dead zones without the need for a guide plate and with only one inlet and one outlet on the electrode frame. In other words, this invention solves the problems caused by guide plates while simplifying the design of the flow channels on the external electrode frame and reducing the cost of the external electrode frame.
[0079] Example 5
[0080] Thick carbon felt (4.5 mm) and thin carbon felt (3.5 mm) were used as electrode layers, and a 0.6 mm flexible graphite plate was used as the electrode plate layer. The results were compared between using a conductive adhesive layer (same composition and thickness as in Example 3) and not using a conductive adhesive layer. Contact resistance under different pressures was measured according to "NB / T42007-2013 Test Method for Bipolar Plates for Vanadium Redox Flow Batteries". The results are as follows: Figure 9 As shown, it can be seen that after bonding with a conductive adhesive layer, the contact resistance is greatly reduced on the one hand, and on the other hand, the contact resistance of the carbon felt, regardless of its thickness, will not change much under any pressure. This ensures that the contact resistance of the composite electrode with thin and thick combination provided in this application is basically consistent throughout the electrode area after the stack is assembled, and there will be no local overheating.
[0081] This utility model embodiment also provides a flow battery, which includes the composite electrode provided in any of the above embodiments. Since the flow battery possesses all the technical features of the composite electrode provided in any of the above embodiments, it has the same technical effects as the aforementioned composite electrode.
[0082] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A composite electrode, characterized in that, include: Electrode layer; as well as An electrode layer is stacked on one side of the electrode plate layer or symmetrically stacked on both sides of the electrode plate layer. The electrode layer includes a first edge electrode near the electrolyte inlet on the electrode frame, a second edge electrode near the electrolyte outlet on the electrode frame, and an electrode body connecting the first edge electrode and the second edge electrode. The thickness of the first edge electrode is less than the thickness of the electrode body, and the thickness of the second edge electrode is less than the thickness of the electrode body.
2. The composite electrode as described in claim 1, characterized in that, The first edge electrode and / or the second edge electrode are provided with a flow-diverting structure capable of dispersing the electrolyte.
3. The composite electrode as described in claim 2, characterized in that, The flow splitting structure includes a plurality of flow splitting cavities or flow splitting grooves uniformly distributed on the first edge electrode and / or the second edge electrode; or, the flow splitting structure includes a plurality of strip-shaped branch channels uniformly distributed on the first edge electrode and / or the second edge electrode.
4. The composite electrode as described in claim 1, characterized in that, The ratio of the sum of the areas of the first edge electrode and the second edge electrode to the area of the electrode body is (2-3):(7-8).
5. The composite electrode as described in claim 1, characterized in that, The thickness of the first edge electrode and / or the second edge electrode is 3 to 4.5 mm.
6. The composite electrode as described in claim 1, characterized in that, The thickness of the electrode body is 4.5 to 5.5 mm.
7. The composite electrode according to any one of claims 1 to 6, characterized in that, The composite electrode further includes a conductive adhesive layer disposed between the electrode layer and the plate layer.
8. The composite electrode as described in claim 7, characterized in that, The thickness of the conductive adhesive layer is 0.01 to 0.3 mm.
9. A composite electrode, characterized in that, include: Electrode layer; as well as An electrode layer is stacked on one side of the electrode plate layer or symmetrically stacked on both sides of the electrode plate layer. The electrode layer includes an electrode body, a first edge electrode near the electrolyte inlet on the electrode frame, and two second edge electrodes near the electrolyte outlet on the electrode frame. The first edge electrode is located on the side of the electrode body near the electrolyte inlet, and the two second edge electrodes are respectively located at two corners of the electrode body on the side near the electrolyte outlet. The thickness of the first edge electrode is less than the thickness of the electrode body, and the thickness of the second edge electrode is less than the thickness of the electrode body.
10. A flow battery, characterized in that, Includes the composite electrode as described in any one of claims 1 to 9.