Integrated electrode with flow channel, preparation method of integrated electrode and all-vanadium redox flow battery stack

Abstract

The invention discloses an integrated electrode with a flow channel, a preparation method thereof and an all-vanadium redox flow battery stack, the integrated electrode with the flow channel is of a layered composite structure, the integrated electrode comprises an upper layer hardened graphite felt, and the upper layer hardened graphite felt is cut along an electrolyte flowing direction to form a flow channel pattern; a bottom-layer graphite felt serving as an electrochemical reaction basic carrier is arranged below the upper-layer hardened graphite felt; a middle conductive adhesive film layer for fixedly connecting the upper-layer hardened graphite felt and the bottom-layer graphite felt and ensuring interlayer conduction is arranged between the upper-layer hardened graphite felt and the bottom-layer graphite felt, and the upper-layer hardened graphite felt and the bottom-layer graphite felt are connected through the middle conductive adhesive film layer to jointly define a continuous electrolyte flow channel; the density of the upper-layer hardened graphite felt is 0.3-0.6 g / cm < 3 >, and the density of the bottom-layer graphite felt is 0.1-0.2 g / cm < 3 >. The problems that an existing flow field is high in processing cost, long in period, complex in assembly and insufficient in electrochemical reaction site are solved, and collaborative optimization of low-cost preparation, convenient assembly and stack performance improvement of the flow field is achieved.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery technology, specifically to an integrated electrode with flow channels, its preparation method, and a vanadium redox flow battery stack. Background Technology

[0002] Vanadium redox flow batteries, due to their high safety, long lifespan, and the ability to independently design power and capacity, have shown broad application prospects in large-scale energy storage, especially in renewable energy grid integration. The flow field and electrodes are the core components of the fuel cell stack, and their structure and performance directly determine the stack's reaction efficiency, concentration polarization, assembly difficulty, and production cost.

[0003] In existing technologies, the flow field and electrodes are mostly separate structures, and there are two main types of mainstream solutions and their drawbacks: (1) Graphite bipolar plate engraving flow field: The flow channel is processed by CNC engraving and other methods on a thick graphite bipolar plate. This method has problems such as high processing cost, long cycle (complex flow channels can take several weeks) and low material utilization. The thicker bipolar plate (usually >5mm) also increases the fuel cell stack volume and internal resistance, and reduces the volumetric energy density.

[0004] (2) Flow field of the guide frame and carbon paper flow channel plate splicing: The guide frame and the prefabricated carbon paper flow channel plate are spliced ​​together. Although this method reduces the processing difficulty of bipolar plates, the assembly process is complicated and requires precise alignment. Moreover, the splicing interface is prone to misalignment, leakage or even blockage under long-term operation or assembly error, which affects the reliability and life of the fuel cell stack.

[0005] In addition, in the split structure, the electrolyte needs to flow through the channel before diffusing into the porous electrode to react. The reaction sites are mostly concentrated near the interface where the electrode and the channel contact each other, and the mass transfer inside the electrode is limited, so the overall reaction area cannot be fully utilized.

[0006] Therefore, there is an urgent need for an integrated innovative structure that can organically combine flow field with electrode function and solve processing, assembly and performance problems at the same time. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an integrated electrode with flow channels and its preparation method and an all-vanadium redox flow battery stack, so as to solve the problems of high processing cost, long cycle, complex assembly and insufficient electrochemical reaction sites of existing flow fields, and to achieve synergistic optimization of low-cost preparation of flow fields, convenient assembly and improved performance of the stack.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0009] The integrated electrode with flow channels has a layered composite structure, including an upper layer of hardened graphite felt with flow channel patterns cut along the electrolyte flow direction. Below the upper layer is a lower layer of graphite felt serving as a carrier for the electrochemical reaction. An intermediate conductive film layer connects the upper and lower layers, ensuring interlayer conductivity. The upper and lower layers, connected by the intermediate conductive film layer, together define a continuous electrolyte flow channel. The density of the upper layer of hardened graphite felt is 0.3-0.6 g / cm³. 3 The density of the underlying graphite felt is 0.1-0.2 g / cm³. 3 .

[0010] Preferably, the electrolyte flow channel is serpentine, and the spacing between adjacent flow channels is 3-6 mm.

[0011] Preferably, the cross-section of the electrolyte flow channel is U-shaped, V-shaped, or rectangular, the channel depth is 1-3 mm, and the channel width is 2-5 mm.

[0012] Preferably, the intermediate conductive adhesive film layer has a mesh structure and a thickness of 0.02-0.04 mm.

[0013] Preferably, the upper and lower surfaces of the integrated electrode with flow channels are respectively covered with conductive coatings to enhance surface flatness and current collection performance; the conductive coating is made of graphite powder modified epoxy resin and has a thickness of 0.05-0.10 mm.

[0014] The method for fabricating an integrated electrode with flow channels includes the following steps: S1. Cutting: The upper hardened graphite felt is cut using a pressure cutting machine to form a flow channel pattern; S2. Adhesive film: A conductive adhesive film is laid or coated on the upper surface of the bottom graphite felt to form a composite of the middle conductive adhesive film layer and the bottom graphite felt. S3. Bonding and curing: The upper hardened graphite felt with flow channel pattern obtained in step S1 is bonded to the middle conductive adhesive film layer of the composite obtained in step S2, and placed in a hot press device for hot pressing and curing at a preset temperature and pressure to bond the three-layer structure into one, thus obtaining an integrated electrode blank with flow channel. S4. Post-processing: Conductive adhesive is coated on the upper and lower surfaces of the electrode blank, and then dried or cured to form a conductive coating, thus obtaining an integrated electrode with flow channels.

[0015] Preferably, in step S3, the temperature for hot pressing curing is 80-100℃, the pressure is 0.5-1MPa, and the time is 2-30 minutes.

[0016] A vanadium redox flow battery stack with integrated flow channel electrodes includes a plurality of stacked individual cells and end plates located on both sides of the individual cells. The end plates are tightened and fixed together by a pull rod and a nut threaded to the end of the pull rod. The individual cell includes a separator, two integrated flow channel electrodes attached to both sides of the separator, and two bipolar plates respectively attached to the outside of the two integrated flow channel electrodes. Adjacent stacked individual cells share a bipolar plate. The stack also includes a flow guide frame that corresponds one-to-one with the integrated flow channel electrodes to assemble the integrated flow channel electrodes.

[0017] Preferably, the diaphragm is a perfluorosulfonic acid resin membrane; the bipolar plate is made of carbon composite material, and its surface has an electrolyte inlet and an electrolyte outlet that are connected to the electrolyte flow channel of the adjacent integrated electrode with flow channel, and the electrolyte inlet and electrolyte outlet are connected to the inlet manifold and outlet manifold respectively provided on one end plate.

[0018] Preferably, the planar dimension of the integrated electrode with flow channel is larger than the corresponding dimension of the inner frame of the flow guide frame, and the integrated electrode with flow channel is interference-fitted with the flow guide frame.

[0019] Due to the adoption of the above technical solutions, the technical progress achieved by this invention is as follows.

[0020] This invention completely solves the problems of misalignment and detachment during assembly, significantly improving the reliability of the fuel cell stack. By adopting an integrated flow channel-electrode structure, the flow guiding and reaction functions are combined into a single component, fundamentally eliminating the assembly interface between the flow channel plate and the electrode. More importantly, by designing the planar dimensions of the integrated flow channel electrode to be slightly larger than the inner frame dimensions of the flow guiding frame, its own elasticity achieves interference fit and elastic support. After assembly, the electrode is firmly embedded in the flow guiding frame, and even if the fuel cell stack is flipped on the assembly line, there is no risk of the component falling off, greatly improving the assembly reliability and long-term operational stability of the fuel cell stack.

[0021] This invention significantly simplifies the fuel cell stack assembly process, increasing assembly efficiency by over 60% and reducing labor and time costs: by integrating the flow channels and electrodes into a single standardized component. During fuel cell stack assembly, operators only need to stack the components sequentially, reducing assembly steps by over 40%, lowering precision requirements, and shortening the total assembly time by over 60%. This is particularly suitable for large-scale mass production, significantly reducing production costs and increasing capacity.

[0022] This invention significantly improves electrochemical reaction efficiency and stack power performance, increasing the effective reaction area by 30%-60%. The integrated electrode adopts a gradient density design with a denser upper layer and a sparser lower layer. The upper high-density region forms a stable flow channel, guiding the directional flow of the electrolyte; the lower high-porosity region serves as the main reaction zone. Under pressure, the electrolyte can actively and rapidly penetrate vertically from the upper flow channel to the entire porous region of the lower layer. This "flow field embedded inside the electrode" design allows for more thorough contact between the electrolyte and the electrode material, increasing the effective electrochemical reaction area (specific surface area) by 30%-60% compared to traditional structures, and also significantly increasing the number of reaction sites. The direct effect is a reduction in electrochemical polarization and concentration polarization, enabling the stack to operate at higher current densities, with significantly improved voltage and energy efficiency (e.g., at 100 mA / cm²). 2 The voltage efficiency can be improved by 8%, thereby increasing the power density and overall performance of the fuel cell stack. In practical applications, renewable energy generation such as photovoltaics and wind power generally suffers from intermittency and volatility, requiring supporting energy storage systems to have the ability to quickly adjust their charge and discharge states. The improved reaction rate of the vanadium redox flow battery stack effectively avoids energy loss caused by reaction lag.

[0023] This invention significantly reduces the processing cost and cycle time of flow field components, avoiding high-precision engraving processes: the flow field is formed through a simple and rapid mechanical processing method of pressing and cutting graphite felt, resulting in low equipment costs and high processing efficiency (single-piece processing time is measured in minutes). Simultaneously, the overall thickness of the integrated electrode can be controlled to approximately 4mm, replacing the traditional 5-8mm thick engraved graphite bipolar plate. While achieving the same or even better functionality, it saves a significant amount of expensive graphite material, reducing the cost of a single plate by more than 30%.

[0024] This invention optimizes the fuel cell stack structure, improving volumetric energy density and power density, and making it more suitable for compact energy storage system designs. Because the integrated electrode incorporates flow channel functionality, there is no need for separate thick bipolar plates or flow channel plates, allowing for a significant reduction in the thickness of a single cell. Compared to traditional structures, the fuel cell stack using this invention can increase volumetric energy density by 15%-25%. This is particularly important for space-constrained energy storage applications (such as containerized energy storage systems), meaning that more battery capacity or power modules can be arranged within the same space, improving the economics and competitiveness of the energy storage system.

[0025] The preparation process of this invention is simple, efficient, and easy to scale up for mass production, resulting in consistent product quality. The core steps of the preparation method provided by this invention are only cutting, film application, and hot-press curing. The process is simple, and the parameters are easy to control. The equipment used (such as pressure cutting machines and hot presses) are all general-purpose equipment, eliminating the need for expensive specialized machine tools. This process route is mature and stable, suitable for continuous or batch production, and ensures consistent product performance. Furthermore, the wide process window (e.g., hot-pressing temperature 80-100℃) provides flexibility for production adjustments, further reducing production costs and quality risks.

[0026] In summary, this invention, through its integrated and gradient innovative design, collaboratively solves the long-standing triangular problem in the field of vanadium redox flow batteries—the difficulty in balancing performance, cost, and reliability—and provides key components and technical solutions for achieving low-cost, highly reliable, and high-performance vanadium redox flow battery energy storage systems. Attached Figure Description

[0027] Figure 1 This is a top view of the integrated electrode with flow channels of the present invention; Figure 2 This is a first-view structural schematic diagram of the integrated electrode with flow channel of the present invention; Figure 3 This is a second-view structural schematic diagram of the integrated electrode with flow channel of the present invention; Figure 4 For the present invention Figure 2 Enlarged diagram of point A in the diagram; Figure 5 This is a schematic diagram of the structure of the all-vanadium redox flow battery stack with integrated electrode with flow channel according to the present invention. Figure 6 This is a perspective view of the vanadium redox flow battery stack with integrated electrodes and flow channels according to the present invention.

[0028] Among them: 1. Upper hardened graphite felt, 11. Flow channel pattern, 2. Middle conductive adhesive film layer, 3. Bottom graphite felt, 4. Electrolyte flow channel, 100. Single cell, 101. Separator, 102. Integrated electrode with flow channel, 103. Bipolar plate, 200. Flow guide frame, 300. End plate, 301. Inlet manifold, 302. Outlet manifold, 400. Pull rod, 500. Nut, 600. Baffle. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] An integrated electrode with flow channels, combined with Figures 1 to 4As shown, it is a layered composite structure, including an upper hardened graphite felt 1, an intermediate conductive adhesive film layer 2 and a bottom graphite felt 3 arranged sequentially from top to bottom, and the density of the upper hardened graphite felt 1 is higher than the density of the bottom graphite felt 3.

[0031] The upper hardened graphite felt 1 is cut along the direction of electrolyte flow to form a flow channel pattern 11.

[0032] The underlying graphite felt 3 serves as the basic carrier for electrochemical reactions.

[0033] An intermediate conductive adhesive film layer 2 is disposed between the upper hardened graphite felt 1 and the lower graphite felt 3. The intermediate conductive adhesive film layer 2 has a mesh structure and a thickness of 0.02-0.04 mm, and is used to fix and connect the two layers and ensure interlayer conductivity. After the upper hardened graphite felt 1 and the lower graphite felt 3 are connected by the intermediate conductive adhesive film layer 2, they jointly define a continuous electrolyte flow channel 4, which has the function of guiding electrolyte flow.

[0034] The electrolyte flow channel 4 is serpentine, with a spacing of 3-6 mm between adjacent channels. The cross-section of the electrolyte flow channel 4 is U-shaped, V-shaped, or rectangular, with a channel depth of 1-3 mm and a channel width of 2-5 mm.

[0035] The density of the upper hardened graphite felt 1 is 0.3-0.6 g / cm³. 3 The high-density upper-layer hardened graphite felt 1 can construct stable flow channels and provide mechanical support. Specifically, its high density, after hardening treatment, gives it excellent dimensional stability and mechanical strength. This ensures that the flow channel pattern 11 formed by cutting is not easily deformed or collapsed during subsequent processing, assembly, and long-term operation, and can always maintain a precise geometric shape, ensuring the controllability of electrolyte distribution.

[0036] The density of the bottom graphite felt 3 is 0.1-0.2 g / cm³. 3 The bottom graphite felt 3 serves as the main electrochemical reaction zone. Its lower density implies higher porosity and specific surface area, providing the maximum number of active sites for the redox reaction of vanadium ions, making it the "main battlefield" for electrochemical energy conversion. Simultaneously, it promotes electrolyte penetration and storage: the abundant pore structure facilitates rapid electrolyte wetting, ion transport, and local storage, reducing mass transfer resistance.

[0037] The design of having a higher density of the upper hardened graphite felt 1 than the lower graphite felt 3 allows a single integrated electrode with flow channels to simultaneously meet multiple interrelated and often contradictory technical requirements, such as "stable flow channel structure", "efficient electrolyte distribution", "maximum reaction area", "smooth electron and ion conduction" and "reliable and convenient assembly", thereby synergistically achieving the goals of improving performance, simplifying processes, and reducing costs.

[0038] The upper and lower surfaces of the integrated electrode with flow channels are also covered with conductive coatings. The conductive coatings are made of graphite powder modified epoxy resin and have a thickness of 0.05-0.10 mm, which are used to enhance surface smoothness and current collection performance.

[0039] To better illustrate the technical solution of the present invention, the following are several specific embodiments of the integrated electrode with flow channel: Example

[0040] In this embodiment, the density of the upper hardened graphite felt 1 is 0.3 g / cm³. 3 The thickness is 2mm; the density of the bottom graphite felt 3 is 0.1 g / cm³. 3 The electrode has a thickness of 2 mm. The intermediate conductive adhesive film layer 2 is a mesh structure with a thickness of 0.03 mm. The electrolyte flow channel 4 is serpentine, with an adjacent channel spacing of 4 mm, a U-shaped cross-section, a depth of 2 mm, and a width of 5 mm. The conductive coatings on the upper and lower surfaces are graphite-modified epoxy resin adhesives with a coating thickness of 0.08 mm. The measured total thickness of this electrode is approximately 4.19 mm, and the mass per unit area is approximately 1.2 kg / m³. 2 At 100 mA / cm 2 Simulation tests at current density showed that its effective reaction area was increased by about 45% compared to the traditional split electrode structure. Example

[0041] In this embodiment, the density of the upper hardened graphite felt 1 is 0.4 g / cm³. 3 The thickness is 1.5 mm; the density of the bottom graphite felt 3 is 0.1 g / cm³. 3 The electrode has a thickness of 2.5 mm. The intermediate conductive adhesive film layer 2 is a mesh structure with a thickness of 0.02 mm. The electrolyte flow channel 4 is serpentine, with an adjacent channel spacing of 5 mm. The channel cross-section is rectangular, with a depth of 1.5 mm and a width of 3 mm. The conductive coating thickness on the upper and lower surfaces is 0.05 mm. The measured total thickness of this electrode is approximately 4.12 mm, and the mass per unit area is approximately 1.05 kg / m³. 2 Simulation tests show that its effective reaction area is increased by about 35%. Example

[0042] In this embodiment, the density of the upper hardened graphite felt 1 is 0.5 g / cm³. 3 The thickness is 1.8 mm; the density of the bottom graphite felt 3 is 0.15 g / cm³. 3The electrode has a thickness of 1.8 mm. The intermediate conductive adhesive film layer 2 is a mesh structure with a thickness of 0.04 mm. The electrolyte flow channel 4 is serpentine, with an adjacent channel spacing of 3 mm, a V-shaped cross-section, a depth of 1.5 mm, and a top opening width of 2 mm. The conductive coating thickness on the upper and lower surfaces is 0.10 mm. The measured total thickness of this electrode is approximately 3.84 mm, and the mass per unit area is approximately 1.3 kg / m³. 2 Simulation tests show that its effective reaction area is increased by about 40%.

[0043] The above embodiments demonstrate that, through the gradient density design and integrated composite structure of the present invention, an integrated electrode with both good current conduction function and high reactivity can be obtained under different parameter combinations, and the electrode thickness can be controlled to about 4 mm, verifying the flexibility and effectiveness of the design.

[0044] A method for fabricating an integrated electrode with flow channels includes the following steps: S1. Cutting: The upper hardened graphite felt 1 is cut using a pressure cutting machine to form a flow channel pattern 11.

[0045] S2. Adhesive film: A conductive adhesive film is laid or coated on the upper surface of the bottom graphite felt 3 to form a composite of the intermediate conductive adhesive film layer 2 and the bottom graphite felt 3.

[0046] S3. Bonding and curing: The upper hardened graphite felt 1 with flow channel pattern 11 obtained in step S1 is bonded to the middle conductive adhesive film layer 2 of the composite obtained in step S2, and placed in a hot press equipment for hot pressing and curing at a preset temperature and pressure to bond the three-layer structure into one, thus obtaining an integrated electrode blank with flow channel.

[0047] S4. Post-processing: Conductive adhesive is coated on the upper and lower surfaces of the electrode blank, and then dried or cured to form a conductive coating, thus obtaining an integrated electrode with flow channels.

[0048] In this step, the hot-press curing temperature is 80-100℃, the pressure is 0.5-1MPa, and the time is 2-30 minutes.

[0049] To more clearly demonstrate the process window and feasibility of this preparation method, the following are several specific process examples: Example B1 (for preparing the electrode of Example A1) S1: Select a density of 0.3 g / cm³ 3 Hardened graphite felt with a thickness of 2mm is cut through along a serpentine path using a CNC pressure cutting machine to form a flow channel pattern with a spacing of 4mm and a U-shaped cross section (2mm deep and 5mm wide).

[0050] S2: Select a density of 0.1 g / cm³ 3A 2mm thick graphite felt is used as the bottom layer, and a 0.03mm thick mesh conductive adhesive film (made of graphite powder modified epoxy resin) is laid on its surface.

[0051] S3: Align the cut upper layer components and attach them to the adhesive film, place them in a flatbed hot press, and heat-press and cure for 2 minutes at a temperature of 100℃ and a pressure of 0.5MPa.

[0052] S4: Remove the cured electrode blank and evenly coat its upper and lower surfaces with graphite powder modified epoxy resin adhesive. The coating thickness is controlled to be 0.08mm. Cur it in an oven at 60℃ for 30 minutes.

[0053] The resulting electrode has a total thickness of approximately 4.19 mm, clear flow channels, and strong interlayer bonding. Testing showed that the interlayer contact resistance is less than 5 mΩ·cm. 2 .

[0054] Example B2 (for preparing the electrode of Example A2) S1: Select a density of 0.4 g / cm³ 3 Hardened graphite felt with a thickness of 1.5mm was press-cut into a serpentine flow channel pattern (5mm spacing, rectangular cross section, 1.5mm deep and 3mm wide).

[0055] S2: Select a density of 0.1 g / cm³ 3 A 2.5mm thick graphite felt is used as the bottom layer, and a mesh conductive adhesive film is laid on its surface to form an adhesive layer with a thickness of about 0.02mm.

[0056] S3: Attach the upper components and heat-press them for 10 minutes at a temperature of 90℃ and a pressure of 0.8MPa.

[0057] S4: Spray conductive adhesive (graphite / epoxy resin system) onto the upper and lower surfaces of the electrode. The coating thickness is about 0.05 mm. Let it cure at room temperature for 24 hours.

[0058] The resulting electrode has a total thickness of approximately 4.12 mm, a smooth surface, and precise flow channel dimensions.

[0059] Example B3 (for preparing the electrode of Example A3) S1: Select a density of 0.5 g / cm³ 3 Hardened graphite felt with a thickness of 1.8mm was press-cut into a serpentine flow channel pattern (3mm spacing, V-shaped cross section, 1.5mm depth, and 2mm top opening width).

[0060] S2: Select graphite felt with a density of 0.15 g / cm³ and a thickness of 1.8 mm as the bottom layer, and lay a pre-impregnated conductive film with a thickness of 0.04 mm.

[0061] S3: Attach the upper components and heat-press them for 5 minutes at a temperature of 80℃ and a pressure of 1MPa.

[0062] S4: Remove the cured electrode blank and evenly coat its upper and lower surfaces with graphite-modified epoxy resin adhesive. The coating thickness is about 0.10 mm. Cure at 80°C for 1 hour.

[0063] The total thickness of the resulting electrode is approximately 3.84 mm, the flow channel edges are smooth, and the overall rigidity of the electrode is good.

[0064] The above process examples demonstrate that the preparation method of the present invention has clear process parameters and good operability. It can stably prepare integrated electrodes that meet design requirements under different process conditions, verifying the practicality and reproducibility of the technical solution of the present invention.

[0065] A vanadium redox flow battery stack with integrated electrodes and flow channels, such as Figures 5 to 6 As shown, the stack includes several stacked individual cells 100 and end plates 300 located on both sides of the individual cells 100. The two end plates 300 are tightened and fixed by a pull rod 400 and a nut 500 threaded to the end of the pull rod 400, thereby providing uniform and sufficient sealing pressure for the entire stack.

[0066] A single cell 100 includes a separator 101, two integrated electrodes with flow channels 102, and two bipolar plates 103. The two integrated electrodes with flow channels 102 are respectively attached to both sides of the separator 101; the two bipolar plates 103 are respectively attached to the outside of the two integrated electrodes with flow channels 102, and adjacent stacked single cells 100 share a bipolar plate 103. This shared structure avoids the duplication of bipolar plates 103 and makes the stack structure more compact.

[0067] The diaphragm 101 is a perfluorosulfonic acid resin membrane sandwiched between two integrated electrodes 102 with flow channels, used to isolate the positive and negative electrolytes and allow protons to pass through.

[0068] The bipolar plate 103 is made of carbon composite material and has an electrolyte inlet and an electrolyte outlet on its surface. The electrolyte inlet and electrolyte outlet are connected to the electrolyte flow channel 4 of the adjacent integrated electrode 102 with flow channel. The end plate 300 is provided with an inlet manifold 301 and an outlet manifold 302. The electrolyte inlet and electrolyte outlet are also connected to the inlet manifold 301 and the outlet manifold 302 provided on one end plate 300 to realize electrolyte circulation.

[0069] The fuel cell stack also includes flow guide frames 200, each corresponding to an integrated electrode 102 with a flow channel, which house the integrated electrode 102. Specifically, the planar dimensions of the integrated electrode 102 are slightly larger than the corresponding dimensions of the inner frame of the flow guide frame 200 (e.g., length and width are both greater than 0.3-1.0 mm, preferably 0.5 mm), and the integrated electrode 102 is interference-fitted with the flow guide frame 200 by its own elasticity to prevent it from falling off.

[0070] A baffle 600 is also sandwiched between the two end plates 500. The baffle 600 encloses several single batteries 100 and the current guide frame 200, and plays a role in protection and fixation.

[0071] The working principle of the fuel cell stack is as follows: The positive and negative electrolytes are pumped into the corresponding electrolyte channels 4 through the main inlet pipe 301 on the end plate 300 and the electrolyte inlet on the bipolar plate 103, respectively. Driven by pressure, the electrolyte flows within the electrolyte channels 4 while vertically penetrating the mesh pores of the intermediate conductive adhesive film layer 2, rapidly and uniformly wetting the entire bottom graphite felt 3. On the large active surface of the bottom graphite felt 3, vanadium ions undergo a redox reaction (during charging: VOO2O3 ... 2+ +H2O→VO2 + +2H + +e⁻; the opposite occurs during discharge). Electrons generated by the reaction are conducted through the conductive bottom graphite felt 3, the intermediate adhesive film layer 2, and the upper hardened graphite felt 1 to the bipolar plate 103, and then form a current through the external circuit. The protons (H) generated by the reaction... + The electrolyte then passes through the middle diaphragm 101 and migrates between the positive and negative electrodes to maintain charge balance. The electrolyte after the reaction flows out through the electrolyte outlet on the bipolar plate 103 and the liquid outlet manifold 302 on the end plate 300.

[0072] The charge-discharge performance of the above-mentioned fuel cell stack was tested. The test results show that the fuel cell stack using the integrated electrode with flow channel of the present invention has a comprehensive improvement in performance: the effective electrochemical reaction area is increased by about 40% compared with the traditional graphite bipolar plate flow field fuel cell stack, which not only increases the number of reaction sites but also reduces concentration polarization; at the same time, the assembly time of the fuel cell stack is significantly reduced from about 4 hours for the traditional structure to about 1.2 hours, and the assembly efficiency is improved by more than 65%; at 100 mA / cm 2 At the current density, the voltage efficiency of the fuel cell stack was improved by approximately 8%, while the internal resistance of the stack was reduced by approximately 22%. These combined performance improvements enable the fuel cell stack to operate more efficiently and reduce energy losses due to lag when responding to the fluctuating charging and discharging demands of new energy sources.

Claims

1. An integrated electrode with flow channels, characterized in that: The structure is a layered composite structure, including an upper hardened graphite felt (1), on which a flow channel pattern (11) is cut along the electrolyte flow direction; a lower layer graphite felt (3) is disposed below the upper hardened graphite felt (1) as a basic carrier for electrochemical reaction; an intermediate conductive adhesive film layer (2) is disposed between the upper hardened graphite felt (1) and the lower layer graphite felt (3) to fix and connect the two and ensure interlayer conductivity, and the upper hardened graphite felt (1) and the lower layer graphite felt (3) are connected by the intermediate conductive adhesive film layer (2) to jointly define a continuous electrolyte flow channel (4); the density of the upper hardened graphite felt (1) is 0.3-0.6 g / cm³. 3 The density of the bottom graphite felt (3) is 0.1-0.2 g / cm³. 3 .

2. The integrated electrode with flow channel according to claim 1, characterized in that: The electrolyte flow channel (4) is serpentine, and the distance between adjacent flow channels is 3-6 mm.

3. The integrated electrode with flow channel according to claim 1, characterized in that: The cross-section of the electrolyte channel (4) is U-shaped, V-shaped or rectangular, the channel depth is 1-3 mm and the channel width is 2-5 mm.

4. The integrated electrode with flow channel according to claim 1, characterized in that: The intermediate conductive adhesive film layer (2) has a mesh structure and a thickness of 0.02-0.04 mm.

5. The integrated electrode with flow channel according to claim 1, characterized in that: The upper and lower surfaces of the integrated electrode with flow channels are respectively covered with conductive coatings to enhance surface flatness and current collection performance; the conductive coating is made of graphite powder modified epoxy resin and has a thickness of 0.05-0.10 mm.

6. The method for fabricating an integrated electrode with flow channels as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Cutting: The upper hardened graphite felt (1) is cut using a pressure cutting machine to form a flow channel pattern (11). S2. Adhesive film: A conductive adhesive film is laid or coated on the upper surface of the bottom graphite felt (3) to form a composite of the intermediate conductive adhesive film layer (2) and the bottom graphite felt (3); S3. Bonding and curing: The upper hardened graphite felt (1) with flow channel pattern (11) obtained in step S1 is bonded to the middle conductive adhesive film layer (2) of the composite obtained in step S2, and placed in a hot press device for hot pressing and curing under preset temperature and pressure to bond the three-layer structure into one, thereby obtaining an integrated electrode blank with flow channel. S4. Post-processing: Conductive adhesive is coated on the upper and lower surfaces of the electrode blank, and then dried or cured to form a conductive coating, thus obtaining an integrated electrode with flow channels.

7. The method for fabricating an integrated electrode with flow channels according to claim 6, characterized in that: In step S3, the hot-press curing temperature is 80-100℃, the pressure is 0.5-1MPa, and the time is 2-30 minutes.

8. A vanadium redox flow battery stack with integrated flow channel electrodes, comprising a plurality of stacked individual cells (100) and end plates (300) located on both sides of the plurality of individual cells (100), wherein the end plates (300) are tightened and fixed together by through-through tie rods (400) and nuts (500) threaded to the ends of the tie rods (400), characterized in that: The single cell (100) includes a separator (101), two integrated electrodes (102) with flow channels attached to both sides of the separator (101) as described in any one of claims 1 to 5, and two bipolar plates (103) respectively attached to the outside of the two integrated electrodes (102), and adjacent stacked single cells (100) share a bipolar plate (103); the stack also includes a flow guide frame (200) that is configured one-to-one with the integrated electrodes (102) to assemble the integrated electrodes (102).

9. The all-vanadium redox flow battery stack with integrated flow channel electrode according to claim 8, characterized in that: The diaphragm (101) is a perfluorosulfonic acid resin membrane; the bipolar plate (103) is made of carbon composite material, and its surface is provided with an electrolyte inlet and an electrolyte outlet that are connected to the electrolyte flow channel (4) of the adjacent integrated electrode (102) with flow channel, and the electrolyte inlet and electrolyte outlet are connected to the inlet manifold (301) and outlet manifold (302) provided on one end plate (300).

10. The all-vanadium redox flow battery stack with integrated flow channel electrode according to claim 8, characterized in that: The planar dimension of the integrated electrode (102) with flow channel is larger than the corresponding dimension of the inner frame of the flow guide frame (200), and the integrated electrode (102) with flow channel is interference-fitted with the flow guide frame (200).

Images