Plate and frame structure for flow battery stack, flow battery stack and method of processing thereof

Abstract

This invention relates to the field of flow battery stacks, providing a plate-and-frame structure for flow battery stacks, a flow battery stack itself, and a processing method thereof. The plate-and-frame structure for flow battery stacks includes a plate-and-frame substrate and an electrofusion sealing ring; it is integrally formed using a two-color injection molding process, significantly improving the processing efficiency of the plate-and-frame structure. The flow battery stack is composed of multiple plate-and-frame structures fused together by electrofusion sealing rings, effectively simplifying the assembly process of the flow battery stack; adjacent plate-and-frame structures are fused together by electrofusion sealing rings to form an integrated sealing structure, eliminating microscopic leakage gaps and fundamentally avoiding the risk of electrolyte leakage, greatly improving the sealing performance and reliability of the stack. Furthermore, through repeated welding of the electrofusion sealing rings, leakage points in the sealing structure or damaged plate-and-frame structures can be quickly repaired or replaced, improving the maintainability and repair economy of the flow battery stack.

Description

Technical Field

[0001] This invention relates to the field of flow battery stacks, and provides a plate and frame structure for flow battery stacks, a flow battery stack, and a method for processing the same. Background Technology

[0002] As a highly efficient energy storage device, flow battery stacks have demonstrated enormous application potential in large-scale energy storage systems due to their safety and long cycle life. Flow battery stacks generate and store electrical energy through the movement of electrolyte between electrodes; therefore, ensuring effective electrolyte sealing is crucial. However, during long-term operation, traditional rubber sealing materials are prone to aging due to prolonged immersion in electrolyte, leading to shrinkage or hardening of the rubber seals. This increases the leakage rate at the interface between the sealing plates, affecting battery performance.

[0003] To address this issue, bolt-tightening sealing technology is widely used in battery stacks. This technology uses metal screws passing through threaded holes in metal end plates to tightly connect multiple battery cells, achieving a secure connection. However, this method can easily lead to deformation between the bipolar plates and the flow field frame due to pressure during the tightening process, which in turn affects the distribution of electrolyte in the electrode area and reduces the battery's performance stability. Furthermore, existing battery stacks require regular maintenance; if the nuts loosen, electrolyte leakage can occur, ultimately leading to battery failure.

[0004] To address the above issues, adhesive sealing technology has attracted attention as a potential alternative due to its ability to achieve one-piece molding and reduce leakage paths. However, this technology also has some significant drawbacks. Adhesives expand or shrink during curing; for example, epoxy resin adhesives can have a curing shrinkage rate of 1-5%, which may lead to microcracks at the interface or cause internal stress concentration, resulting in seal failure. Furthermore, the sensitivity of adhesives to changes in environmental humidity and temperature makes their curing time and quality susceptible to fluctuations, increasing the risk of bubbles and porosity and reducing their sealing effectiveness. Under prolonged pressure, adhesives can also undergo creep, leading to a decrease in sealing pressure and further increasing the risk of electrolyte leakage. Therefore, while adhesive sealing technology has certain advantages, it still faces many challenges in practical applications. Summary of the Invention

[0005] This invention provides a plate and frame structure for a flow battery stack to address shortcomings such as poor sealing performance in related technologies.

[0006] This invention also provides a method for fabricating a plate and frame structure for a flow battery stack.

[0007] This invention also provides a flow battery stack.

[0008] This invention also provides a method for processing a flow battery stack.

[0009] A first aspect of the present invention provides a plate frame for a battery stack, comprising: a plate frame substrate; and an electrofusion sealing ring, wherein the plate frame substrate and the electrofusion sealing ring are integrally formed by a two-color injection molding process.

[0010] According to one embodiment of the present invention, the plate frame substrate is made of a first thermoplastic material.

[0011] According to one embodiment of the present invention, the electrothermal sealing ring is made of a conductive thermoplastic material, which heats up to a molten state when energized; Alternatively, the electrofusion sealing ring may be made of a second thermoplastic material and have an independent heating wire built in, which heats the electrofusion sealing ring to a molten state when energized; Alternatively, the electrothermal sealing ring may be made of a second thermoplastic material and have a built-in induction circuit that generates eddy currents to heat the electrothermal sealing ring to a molten state when subjected to an external magnetic field.

[0012] According to one embodiment of the present invention, the electrothermal sealing ring comprises: A first sealing ring is provided along the circumference of the plate frame base; The second sealing ring is disposed along the electrolyte reaction area and electrolyte flow channel area on the plate frame substrate.

[0013] According to one embodiment of the present invention, a first sealing groove and a second sealing groove are provided on the plate frame substrate, the first sealing ring is disposed in the first sealing groove, and the second sealing ring is disposed in the second sealing groove; Metal wire circuits are pre-embedded in the first and second sealing rings.

[0014] A second aspect of the present invention provides a method for fabricating the plate and frame structure for a flow battery stack as described above, comprising: The first injection molding is performed using a first thermoplastic material to form the plate-frame matrix; The electrothermal sealing ring is formed by a second injection molding process on the plate frame substrate using a conductive thermoplastic material or a second thermoplastic material.

[0015] According to one embodiment of the present invention, the melting point of the conductive thermoplastic material and the melting point of the second thermoplastic material are lower than the melting point of the first thermoplastic material.

[0016] According to one embodiment of the present invention, the electrothermal sealing ring includes a first sealing ring and a second sealing ring, wherein the injection molding temperature of the first sealing ring is 275 degrees Celsius to 285 degrees Celsius, and the injection molding temperature of the second sealing ring is 315 degrees Celsius to 325 degrees Celsius.

[0017] A third aspect of the present invention provides a flow battery stack, comprising a plurality of stacked plate and frame structures for flow battery stacks as described above.

[0018] A fourth aspect of the present invention provides a method for processing the flow battery stack as described above, comprising: Multiple flow battery stacks are stacked using a plate-and-frame structure; Current is passed through the metal electrodes pre-embedded in the plate frame matrix of multiple flow battery stack plate frame structures and connected to the external circuit to melt the electrothermal sealing ring, so that two adjacent flow battery stack plate frame structures are stacked and connected. Pressure is applied to the molten electrofusion sealing ring and then cooled to fuse adjacent electrofusion sealing rings together.

[0019] According to the battery stack plate frame provided in the first aspect embodiment of the present invention, the plate frame substrate and the electrofusion sealing ring are integrally molded by two-color injection molding, avoiding the assembly gap between the sealing ring and the plate frame substrate in the traditional assembly process, and reducing the path of electrolyte leakage; moreover, the two materials achieve molecular-level fusion during injection molding, resulting in high bonding strength, which can resist long-term electrolyte immersion and temperature fluctuations during stack operation, avoiding sealing failure caused by aging of traditional rubber seals and creep of adhesives, and significantly improving the reliability of stack sealing. The integral molding structure allows the heat of the plate frame substrate to be uniformly transferred to the electrofusion sealing ring. When the stack leaks, only an electric current needs to be passed through the plate frame substrate corresponding to the leak point, and the electrofusion sealing ring in that area can be remelted using Joule heating. After melting, pressure cooling can restore the sealing performance, without disassembling the entire stack, making repair convenient and without damaging the overall structure of the stack. The electrofusion sealing ring is made of thermoplastic material and has the characteristic of being remeltable. When a plate frame in the fuel cell stack needs to be replaced, simply energize the base of the target plate frame and its adjacent plates to melt the electrofusion seal between them, thus severing the connection between the plates. After removing the plate frame to be replaced, insert a new plate frame, re-energize to melt the seal, and pressurize and cool to complete the plate frame replacement. This eliminates the need to discard the entire fuel cell stack, reducing maintenance costs. The two-color injection molding process allows for one-time molding of the plate frame base and the electrofusion seal, eliminating the need to process the plate frame base first and then separately assemble the seal, saving additional steps such as seal positioning, bonding, and inspection. Furthermore, mold switching and material injection processes are continuously controllable, reducing processing time and scrap rates. Compared to traditional split-processing, this significantly improves the processing efficiency of fuel cell stack components.

[0020] According to the processing method of the battery stack frame provided in the second aspect of the present invention, two injection molding processes are performed continuously, eliminating the need to process the frame substrate first and then separately assemble the sealing ring, thus saving additional processes such as sealing ring positioning, bonding, and inspection. The mold switching and material injection process are continuously controllable, reducing waiting time and scrap rate in the processing stages. Compared with traditional split processing technology, this significantly shortens the production cycle of the frame structure and improves production efficiency. The two-color injection molding process enables the frame substrate and the electrofusion sealing ring to achieve molecular-level fusion in the molten state, resulting in a bonding strength far exceeding that of traditional assembly or bonding methods. The joint is gapless and delamination-free, providing long-term resistance to electrolyte immersion, temperature fluctuations, and vibrations during stack operation. This avoids the leakage risk caused by assembly gaps or bonding failures in traditional seals, significantly improving sealing reliability.

[0021] According to the battery stack provided in the third aspect of the present invention, after multiple plate frames are stacked, the electrothermal sealing rings of adjacent plate frames are tightly fitted, and subsequently fused together to form an integrated sealing structure, which greatly improves the reliability of the battery stack sealing and meets the sealing requirements for long-term operation of the battery stack. When a leak occurs in a certain part of the battery stack, the corresponding plate frame can be locally energized, and only the sealing ring in that area needs to be remelted and repaired, without disassembling the entire battery stack, making the repair convenient and efficient. If a plate frame in the battery stack needs to be replaced, the sealing rings of that plate frame and the adjacent plate frames can be melted and separated by energizing, and the plate frame to be replaced can be removed, and a new plate frame can be stacked and fused and sealed, realizing the rapid replacement of the plate frame structure without affecting the performance of other parts of the battery stack. The structure of multiple plate frames is uniform, the stacking process is simple, no complex assembly and adjustment are required, and combined with the efficient processing method of the plate frames themselves, the overall production efficiency of the battery stack is improved.

[0022] According to the battery stack processing method described above, provided in the fourth aspect of the present invention, electrofusion melting enables the electrothermal fusion sealing rings of adjacent plates and frames to achieve molecular-level fusion. Pressure cooling further ensures the tightness of the sealing layer, completely eliminating assembly gaps or microscopic leakage channels present in traditional sealing methods, significantly reducing the risk of electrolyte leakage. The fusion structure of the double sealing rings effectively blocks leakage paths from both the periphery and the core area, providing a durable and stable sealing effect that meets the stringent sealing requirements of long-term operation of flow battery stacks. The fused plate and frame structure forms a robust integrated whole with high connection strength, capable of withstanding pressure, vibration, and temperature fluctuations during stack operation, avoiding sealing failures or structural instability caused by loosening of traditional bolted connections. The integrated structure also ensures the dimensional stability of the internal flow channels and reaction areas of the stack, resulting in uniform electrolyte distribution and ensuring stable electrochemical performance of the stack. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic exploded view of the fuel cell stack provided by the present invention.

[0025] Figure 2 This is a schematic perspective view of the plate frame substrate provided by the present invention from one angle.

[0026] Figure 3 This is a schematic perspective view of the plate frame substrate provided by the present invention from another angle.

[0027] Figure 4 This is a schematic front view of the plate frame base provided by the present invention.

[0028] Figure 5 yes Figure 4 A schematic cross-sectional view along the AA direction.

[0029] Figure label: 100. Plate and frame base; 102. Electrofusion sealing ring; 104. First sealing ring; 106. Second sealing ring; 108. First sealing groove; 110. Second sealing groove. Detailed Implementation

[0030] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0031] like Figures 1 to 5 As shown, a first aspect of the present invention provides a battery stack frame, comprising: Plate frame base 100; The electrothermal sealing ring 102 and the plate frame substrate 100 are integrally formed with the electrothermal sealing ring 102 through a two-color injection molding process.

[0032] The battery stack plate frame provided in the first aspect of the present invention is composed of a plate frame base 100 and an electrothermal sealing ring 102, which are integrally formed by a two-color injection molding process.

[0033] A dedicated two-color injection mold is used, which contains two independent and switchable cavities, corresponding to the shape and size of the plate frame base 100 and the electrofusion sealing ring 102, respectively. A pre-set positioning structure within the mold ensures accurate relative positioning of the materials during the two injection processes, preventing displacement.

[0034] First, the appropriate injection molding material is injected into the first cavity of the mold, which perfectly matches the preset structure of the plate frame substrate 100. During the injection molding process, the mold temperature, injection pressure, and holding time are controlled to ensure that the material fully fills the cavity. After cooling and solidification, a plate frame substrate 100 with a complete structure and precise dimensions is formed. The surface area to be bonded remains smooth, laying the foundation for subsequent fusion with the electrothermal sealing ring 102.

[0035] While maintaining the position of the plate frame substrate 100 within the mold, the mold is switched to the second cavity, and a suitable thermoplastic elastomer material is injected into the second cavity. This cavity precisely matches the shape of the electrofusion sealing ring 102, and the cavity is tightly fitted to the surface of the plate frame substrate 100 to be bonded. During the injection molding process, the thermoplastic elastomer fully contacts and fuses with the surface of the plate frame substrate 100. After cooling, it forms an electrofusion sealing ring 102 that is seamlessly connected to the plate frame substrate 100. There is no delamination or gap at the joint, ultimately forming a battery stack plate frame with the plate frame substrate 100 and the electrofusion sealing ring 102 integrally molded.

[0036] According to the battery stack plate frame provided in the first aspect embodiment of the present invention, the plate frame substrate 100 and the electrothermal sealing ring 102 are integrally molded by two-color injection molding, avoiding the assembly gap between the sealing ring and the plate frame substrate 100 in the traditional assembly process, and reducing the path of electrolyte leakage; moreover, the two materials achieve molecular-level fusion during the injection molding process, with high bonding strength, which can resist the temperature fluctuations during electrolyte immersion and stack operation for a long time, avoiding the sealing failure caused by the aging of traditional rubber seals and the creep of adhesives, and greatly improving the reliability of the stack seal. The integral molding structure allows the heat of the plate frame substrate 100 to be uniformly transferred to the electrothermal sealing ring 102. When the stack leaks, it is only necessary to pass current through the plate frame substrate 100 corresponding to the leakage point, and the electrothermal sealing ring 102 in that area can be remelted by using Joule heat. After melting, pressure cooling can restore the sealing performance, without disassembling the entire stack, making repair convenient and without damaging the overall structure of the stack. The electrothermal sealing ring 102 is made of thermoplastic material and has the characteristic of being remeltable. When a plate frame in the fuel cell stack needs to be replaced, simply energize the base of the target plate frame and its adjacent plate frames to melt the electrothermal sealing ring 102 between them, thus severing the connection between the plate frames. After removing the plate frame to be replaced, insert a new plate frame, re-energize to melt the sealing ring, and pressurize and cool to complete the plate frame replacement. This eliminates the need to discard the entire fuel cell stack, reducing maintenance costs. The two-color injection molding process enables the plate frame base 100 and the electrothermal sealing ring 102 to be formed in one step, eliminating the need to process the plate frame base 100 first and then assemble the sealing ring separately, thus saving additional processes such as sealing ring positioning, bonding, and inspection. Furthermore, the mold switching and material injection process are continuously controllable, reducing waiting time and scrap rate in the processing stages. Compared with traditional split processing technology, this significantly improves the processing efficiency of fuel cell stack components.

[0037] According to one embodiment of the present invention, the plate frame substrate 100 is made of conductive plastic for generating Joule heating when energized.

[0038] In one embodiment of the present invention, the plate frame substrate 100 of the battery stack is made of conductive plastic, which has stable conductivity and good injection molding characteristics. The structural design of the plate frame substrate 100 is adapted to the stacking requirements of the battery stack, and its shape and size are determined according to the stack assembly specifications to ensure that multiple plate frames can be precisely aligned after stacking. The conductivity of the plate frame substrate 100 meets the requirements for heat generation when energized. After current is applied, Joule heating is generated by utilizing the resistive characteristics of the conductive plastic. The heat can be evenly transferred to the electrofusion sealing ring 102 integrally formed with the plate frame substrate 100, providing a stable heat source for the melting of the sealing ring. The conductive path of the plate frame substrate 100 is reasonably designed to ensure uniform current distribution and avoid local overheating or insufficient heat.

[0039] The plate and frame substrate 100 is made of conductive plastic. The Joule heat generated by the current can precisely act on the electrofusion sealing ring 102, causing the sealing rings of adjacent plates and frames to fully melt and fuse together, forming a molecularly bonded sealing structure. This significantly improves the reliability of the fuel cell stack seal and effectively reduces the risk of electrolyte leakage. When a leak occurs in the fuel cell stack, current can be applied again to the plate and frame substrate 100 corresponding to the leak point. The Joule heat will then remelt the electrofusion sealing ring 102 in that area, achieving rapid repair of the leak without disassembling the entire fuel cell stack. If the plate and frame structure in the fuel cell stack needs to be replaced, the target plate and frame can be energized to remelt the fused sealing rings of adjacent plates and frames, severing the connection between them. The plate and frame to be replaced can then be easily removed, replaced, and re-melted for sealing, allowing for repeated disassembly and replacement of the plate and frame. The injection molding process for conductive plastics is mature, and the plate and frame substrate 100 can be completed in a single injection molding process without the need for additional processing of conductive structures, significantly improving the processing efficiency of fuel cell stack components.

[0040] According to one embodiment of the present invention, the plate frame substrate 100 is made of a first thermoplastic material.

[0041] In one embodiment of the present invention, the first thermoplastic material is a modified material with high strength, good injection molding characteristics, and resistance to electrolyte corrosion, which can adapt to the processing requirements of two-color injection molding process, while meeting the structural load-bearing and long-term operation requirements of the flow battery stack. The structural design of the plate frame substrate 100 conforms to the stacking assembly specifications, and the overall outline and dimensions are precisely matched to ensure that multiple plate frames can be accurately aligned after stacking without offset or loosening.

[0042] The plate frame substrate 100 has a pre-set first sealing groove 108 and a second sealing groove 110, which are used to accommodate the first sealing ring 104 and the second sealing ring 106, respectively. The size, depth and distribution of the grooves are optimized to provide a stable mounting base for the sealing rings without affecting the structural strength of the plate frame substrate 100. The surface of the plate frame substrate 100, especially the area where it is combined with the sealing ring, is kept smooth and flat to create conditions for molecular-level fusion with the electrofusion sealing ring 102 during the two-color injection molding process, ensuring that the two are firmly bonded without delamination or gaps.

[0043] The melting point of the first thermoplastic material is selected to be higher than that of the material used in the electrofusion sealing ring 102. When the electrofusion sealing ring 102 is formed by the second injection molding, the plate frame substrate 100 can maintain structural stability and will not deform or degrade due to the temperature of the second injection molding, thus ensuring the reliability of the integral molding structure.

[0044] The high strength of the first thermoplastic material gives the plate-frame matrix 100 good structural rigidity and load-bearing capacity, enabling it to withstand the pre-stress during fuel cell stacking and the working pressure during operation. According to one embodiment of the present invention, the electrothermal sealing ring 102 is made of a conductive thermoplastic material, which heats up to a molten state when energized; Alternatively, the electrothermal sealing ring 102 may be made of a second thermoplastic material and have an independent heating wire built in, which heats the electrothermal sealing ring 102 to a molten state when energized; Alternatively, the electrothermal sealing ring 102 may be made of a second thermoplastic material and have a built-in induction circuit. When subjected to an external magnetic field, it generates eddy currents to heat the electrothermal sealing ring 102 to a molten state.

[0045] In one embodiment of the present invention, the electrothermal sealing ring 102 is integrally molded from a conductive thermoplastic material. This material possesses both good conductivity and thermoplasticity, and can generate Joule heat using its own resistance characteristics when energized, achieving a temperature rise from room temperature to a molten state. The structure of the sealing ring is precisely adapted to the sealing grooves on the plate frame substrate 100, including a first sealing ring 104 disposed circumferentially along the plate frame substrate 100, and a second sealing ring 106 disposed along the electrolyte reaction region and flow channel region, ensuring that the seal covers all potential leakage paths. The melting point of the conductive thermoplastic material is lower than that of the first thermoplastic material of the plate frame substrate 100, and only the sealing ring itself heats up and melts after energization, without affecting the structural stability of the plate frame substrate 100.

[0046] Alternatively, the electrothermal sealing ring 102 is made of a second thermoplastic material, with an independent heating wire embedded inside. The distribution of the heating wire is adapted to the shape of the sealing ring and is evenly arranged inside the first sealing ring 104 and the second sealing ring 106 to form a complete heating circuit. Both ends of the heating wire extend to preset connection points on the plate frame substrate 100 for easy connection to an external circuit. The second thermoplastic material possesses excellent thermoplasticity and resistance to electrolyte corrosion, and its melting point is lower than that of the first thermoplastic material. After energization, the heating wire generates heat and transfers it to the surrounding second thermoplastic material, causing the entire sealing ring to heat up to a molten state, thus achieving the sealing function.

[0047] Alternatively, the electrothermal sealing ring 102 can be made of a second thermoplastic material with an embedded induction circuit. This circuit, made of conductive metal, has a ring-shaped or continuous structure adapted to the shape of the sealing ring, ensuring a tight bond with the second thermoplastic material without the risk of loosening or detachment. The physical properties of the second thermoplastic material are adapted to the induction heating requirements, exhibiting good heat resistance and melt flowability. When a specific frequency magnetic field is applied externally, the induction circuit generates eddy currents under electromagnetic induction. These eddy currents generate heat, causing the sealing ring temperature to rise rapidly until it reaches a molten state, thus meeting the sealing fusion requirements.

[0048] In all three schemes, the electrothermal sealing ring 102 is integrally formed with the plate frame substrate 100 through a two-color injection molding process. The sealing ring fits tightly with the sealing groove of the plate frame substrate 100, with no gaps at the joint, ensuring smooth heat transfer and guaranteeing the sealing performance of the initial assembly.

[0049] All three heating methods can be specifically applied to the electrothermal sealing ring 102, achieving rapid heating to a molten state. The conductive thermoplastic material solution requires no additional heating element; heat is generated directly by the sealing ring itself, resulting in high transfer efficiency. The built-in heating wire solution provides uniform heating and allows for precise control of the heating rate. The built-in induction circuit solution offers non-contact heating, rapid heating without damaging the plate and frame substrate 100. All three solutions ensure that the sealing rings of adjacent plates and frames are fully melted, forming a molecular-level fused sealing structure after pressurization and cooling, eliminating microscopic leakage gaps and significantly improving sealing reliability.

[0050] According to one embodiment of the present invention, the electrothermal sealing ring 102 includes: The first sealing ring 104 is arranged along the circumference of the plate frame base 100; The second sealing ring 106 is provided along the electrolyte reaction area and electrolyte flow channel area on the plate frame substrate 100.

[0051] In one embodiment of the present invention, the first sealing ring 104 is an annular structure that precisely matches the outer circumferential contour of the plate frame base 100 and is continuously arranged along the circumferential edge of the plate frame base 100 to form the first sealing defense line. A first sealing groove 108 is correspondingly provided on the plate frame base 100. The first sealing ring 104 is embedded in the groove and is tightly fused with the groove wall through a two-color injection molding process, without gaps or looseness, ensuring that it completely seals the circumference of the plate frame base 100 and prevents electrolyte leakage from the edge of the plate frame.

[0052] The shape of the second sealing ring 106 is consistent with the contour of the electrolyte reaction area and the electrolyte flow channel area on the plate frame substrate 100, forming a continuous closed structure. It is arranged around the reaction area and the flow channel area to form a second sealing defense line. A second sealing groove 110 is correspondingly opened on the plate frame substrate 100. The second sealing ring 106 is also embedded in the groove through a two-color injection molding process, and is firmly bonded to the groove wall. The arrangement of the second sealing ring 106 completely covers the core area through which the electrolyte flows and reacts, ensuring that the electrolyte only flows within the preset reaction area and flow channel, and will not diffuse or leak to the surrounding area.

[0053] Both the first sealing ring 104 and the second sealing ring 106 are integrally formed with the plate frame substrate 100. They are made of the same conductive thermoplastic material or a second thermoplastic material, possessing the same melting characteristics and resistance to electrolyte corrosion. The two are independent yet work together to form a double sealing structure, blocking leakage paths from both the outer periphery and the core area, ensuring the comprehensiveness and reliability of the seal.

[0054] The first sealing ring 104 forms an outer seal around the plate frame, preventing electrolyte leakage. The second sealing ring 106 precisely seals the core areas where electrolyte reaction and flow occur, preventing electrolyte from flowing or leaking internally. This dual-sealing structure covers all potential leakage paths, significantly improving sealing reliability compared to a single seal. This fundamentally reduces the risk of electrolyte leakage and ensures long-term stable operation of the fuel cell stack.

[0055] According to one embodiment of the present invention, a first sealing groove 108 and a second sealing groove 110 are provided on the plate frame base 100, a first sealing ring 104 is provided in the first sealing groove 108, and a second sealing ring 106 is provided in the second sealing groove 110. Metal wire circuits are pre-embedded in the first sealing ring 104 and the second sealing ring 106.

[0056] In one embodiment of the present invention, a first sealing groove 108 is formed circumferentially along the plate frame base 100, and its outline is precisely adapted to the annular structure of the first sealing ring 104. The depth and width of the groove are designed according to the size of the first sealing ring 104 to ensure that the first sealing ring 104 can fit tightly against the groove wall after being embedded, without loosening or gaps. A second sealing groove 110 is formed around the electrolyte reaction area and electrolyte flow channel area on the plate frame base 100, and its shape is perfectly matched with the second sealing ring 106 to ensure that the second sealing ring 106 can fully cover the core working area and form a precise seal.

[0057] The first sealing ring 104 and the second sealing ring 106 are respectively embedded in the first sealing groove 108 and the second sealing groove 110, and are integrally formed with the plate frame substrate 100 through a two-color injection molding process. The sealing rings and the groove walls achieve molecular-level fusion, resulting in a strong bond. A metal wire circuit is pre-embedded inside the two sealing rings in a continuous ring structure, consistent with the shape of the sealing rings. The metal wire is made of a material with excellent conductivity, high temperature resistance, and resistance to electrolyte corrosion, ensuring that it will not oxidize, break, or degrade in performance during long-term use.

[0058] Both ends of the metal wire circuit extend to the preset connection points of the plate frame substrate 100, facilitating connection with external circuits to form a complete conductive circuit. During the pre-embedding process, the metal wire circuit is completely wrapped by the sealing ring material, isolating it from the electrolyte to prevent corrosion, while ensuring that heat can be evenly transferred to the entire sealing ring, so that the entire sealing ring can be synchronously heated to the molten state.

[0059] The continuous annular layout of the metal wire circuit ensures that the Joule heat generated after energization is evenly distributed throughout the sealing ring, preventing localized overheating or insufficient heat and ensuring that the entire sealing ring heats up to a molten state synchronously. After the sealing rings of adjacent plates and frames melt, they can fully contact and penetrate each other, and after pressurization and cooling, they form a dense, integrated sealing structure, eliminating microscopic leakage gaps and significantly improving sealing reliability.

[0060] A second aspect of the present invention provides a method for processing a battery stack frame as described above, comprising: The first injection molding is performed using a first thermoplastic material to form a plate-frame substrate 100; A second injection molding process is performed on the plate frame substrate 100 using a conductive thermoplastic material or a second thermoplastic material to form an electrothermal sealing ring 102.

[0061] According to the processing method of the battery stack frame provided in the second aspect embodiment of the present invention, two injection molding processes are performed continuously, eliminating the need to process the frame substrate 100 first and then separately assemble the sealing ring, thus saving additional processes such as sealing ring positioning, bonding, and inspection. Mold switching and material injection processes are continuously controllable, reducing waiting time and scrap rate in processing stages. Compared with traditional split processing technology, this significantly shortens the production cycle of the frame structure and improves production efficiency. The two-color injection molding process enables the frame substrate 100 and the electrofusion sealing ring 102 to achieve molecular-level fusion in the molten state, resulting in a bonding strength far exceeding that of traditional assembly or bonding methods. The joint is gapless and delamination-free, capable of long-term resistance to electrolyte immersion, temperature fluctuations, and vibrations during stack operation, avoiding the leakage risk caused by assembly gaps or bonding failures in traditional sealing methods, and significantly improving sealing reliability.

[0062] The battery stack plate frame processing method provided in the second aspect embodiment of the present invention involves integrally molding the plate frame base 100 and the electrothermal sealing ring 102 through two injection molding processes.

[0063] First, a first thermoplastic material is selected as the injection molding raw material. This material has high strength, good injection molding characteristics, and resistance to electrolyte corrosion, and its melting point is higher than that of the material subsequently used for the electrothermal sealing ring 102. A special injection mold is used, and the mold cavity is precisely matched with the preset structure of the plate frame base 100 (including the first sealing groove 108, the second sealing groove 110, and the overall contour).

[0064] Secondly, while maintaining the position of the plate frame substrate 100 within the mold, the mold is switched to a cavity adapted to the electrothermal sealing ring 102, and a conductive thermoplastic material or a second thermoplastic material is selected as the injection molding raw material. This material has excellent thermoplasticity and resistance to electrolyte corrosion, and its melting point is lower than that of the first thermoplastic material, thus avoiding deformation or performance degradation of the plate frame substrate 100 during secondary injection molding.

[0065] If the electrothermal sealing ring 102 needs to be pre-embedded with a metal wire circuit, the metal wire circuit should be pre-placed in the corresponding position of the mold cavity before the second injection molding to ensure that the metal wire circuit is completely wrapped by the sealing ring material after injection molding, and that both ends extend to the preset connection points of the plate frame base 100.

[0066] According to one embodiment of the present invention, the melting point of the conductive thermoplastic material and the melting point of the second thermoplastic material are lower than the melting point of the first thermoplastic material.

[0067] In one embodiment of the present invention, the first thermoplastic material, used as the raw material for manufacturing the plate and frame substrate 100, needs to have a high melting point to ensure that the plate and frame substrate 100 can maintain structural stability during the second injection molding of the electrothermal sealing ring 102, and will not soften, deform, or experience performance degradation due to the high temperature of the second injection molding. Its melting point is precisely selected to meet both the process requirements of injection molding and to provide reliable structural support for the subsequent hot-melt sealing process.

[0068] The conductive thermoplastic material and the second thermoplastic material are used as raw materials for manufacturing the electrothermal sealing ring 102, and their melting points are designed to be lower than those of the first thermoplastic material. This design ensures that during the second injection molding process, the conductive thermoplastic material or the second thermoplastic material can fully melt at a preset temperature and achieve molecular-level fusion with the sealing groove wall of the plate frame substrate 100 to form a strong integrated structure. At the same time, the lower melting point allows the electrothermal sealing ring 102 to rapidly heat up to a molten state at a relatively low temperature in the subsequent hot melt sealing process, achieving sealing fusion between adjacent plates and frames without causing thermal damage to the plate frame substrate 100.

[0069] The differences in melting points of the three materials were optimized and matched to ensure the smooth implementation of the two-color injection molding process, so that the two injection processes do not interfere with each other, and to ensure that the electrothermal sealing ring 102 can be accurately melted in the subsequent heating process, while ensuring the structural integrity and performance stability of the plate frame substrate 100.

[0070] The low melting point design of the conductive thermoplastic material and the second thermoplastic material allows the material to fully melt without damaging the plate and frame substrate 100 during the second injection molding, achieving a tight fusion with the plate and frame substrate 100. This avoids problems such as weak bonding, delamination, or deformation of the plate and frame substrate 100 caused by material melting point mismatch, and greatly improves the integrity and reliability of the plate and frame structure.

[0071] According to one embodiment of the present invention, the electrothermal sealing ring 102 includes a first sealing ring 104 and a second sealing ring 106, wherein the injection molding temperature of the first sealing ring 104 is 275 degrees Celsius to 285 degrees Celsius, and the injection molding temperature of the second sealing ring 106 is 315 degrees Celsius to 325 degrees Celsius.

[0072] In one embodiment of the present invention, after the plate frame substrate 100 cools and solidifies, it maintains its precise positioning within the mold, and the mold cavity is switched to the molding area corresponding to the first sealing ring 104. A conductive thermoplastic material or a second thermoplastic material is selected as the raw material, and the injection temperature is controlled between 275°C and 285°C. This temperature range precisely matches the melting characteristics of the first sealing ring 104 material, ensuring that the material melts fully, possesses good fluidity, and completely fills every detail of the first sealing groove 108, while avoiding excessive temperature leading to material thermal degradation or deformation of the plate frame substrate 100 due to overheating. During the injection molding process, the injection pressure and holding time are controlled to ensure that the molten material adheres tightly to the wall of the first sealing groove 108, achieving molecular-level fusion, and after cooling, forming the first sealing ring 104 arranged circumferentially along the plate frame substrate 100.

[0073] After the first sealing ring 104 cools and solidifies, the positioning of the plate frame substrate 100 remains unchanged, and the mold cavity is switched to the molding area corresponding to the second sealing ring 106. Using the same type of conductive thermoplastic material or a second thermoplastic material, the injection temperature is adjusted to 315°C to 325°C. This temperature range is higher than the injection temperature of the first sealing ring 104 because the second sealing ring 106 is arranged along the electrolyte reaction area and the flow channel area, with a more complex structure and higher requirements for sealing accuracy and bonding strength. A higher injection temperature can further improve the material's fluidity, ensuring that the material fully fills the complex structure of the second sealing groove 110, especially the fine gaps around the flow channel. During injection molding, the temperature, pressure, and holding time are precisely controlled to ensure that the molten material firmly fuses with the wall of the second sealing groove 110 and the core area of ​​the plate frame substrate 100, forming the second sealing ring 106 covering the core working area after cooling.

[0074] Throughout the second injection molding process, the melting point of the first thermoplastic material of the plate and frame substrate 100 is higher than the injection temperature of the second sealing ring 106, ensuring that the plate and frame substrate 100 always maintains structural stability and will not soften or deform due to the high temperature of the second injection molding.

[0075] In other words, injection molding at different temperature ranges was adapted to the structural characteristics and performance requirements of the first and second sealing rings 106. The injection temperature of the first sealing ring 104 ensures complete molding and precise dimensions along the circumferential direction of the plate frame, and a tight fit with the groove; the higher injection temperature of the second sealing ring 106 improves the material flowability, enabling it to completely replicate the complex structure around the reaction area and flow channel, avoiding defects such as material shortages and bubbles. After molding, both have a dense structure and dimensional accuracy that meets the requirements of the electrode stack assembly, laying a good foundation for subsequent sealing and fusion.

[0076] A third aspect of the present invention provides a battery stack, including a plurality of stacked battery stack frames as described above.

[0077] A third aspect of the present invention provides a battery stack, which is composed of multiple battery stack frames stacked sequentially along a predetermined stacking direction. The frame base 100 and the electrofusion sealing ring 102 of each frame are integrally molded by two-color injection molding. During stacking, the positions of adjacent frames are precisely aligned, ensuring a tight fit between the electrofusion sealing ring 102 of the previous frame and the electrofusion sealing ring 102 of the next frame. During stacking, the conductive areas of each frame are ensured to be interconnected, forming a complete current path. Simultaneously, the first sealing ring 104 and the second sealing ring 106 of each frame are respectively fitted together, forming a continuous double-sealed structure that covers all potential leakage paths of the battery stack. After stacking, the overall structure of the battery stack is compact, with no loosening or misalignment between the frames.

[0078] According to the battery stack provided in the third aspect of the present invention, after multiple plate frames are stacked, the electrothermal sealing rings 102 of adjacent plate frames are tightly fitted, and subsequently formed into an integrated sealing structure through melting and fusion, which greatly improves the reliability of the battery stack sealing and meets the sealing requirements for long-term operation of the battery stack. When a leak occurs in a certain part of the battery stack, the corresponding plate frame can be locally energized, and only the sealing ring in that area needs to be remelted and repaired, without disassembling the entire battery stack, making the repair convenient and efficient. If a plate frame in the battery stack needs to be replaced, the sealing rings of that plate frame and the adjacent plate frames can be melted and separated by energizing, and the plate frame to be replaced can be removed, and a new plate frame can be stacked and melted and sealed, realizing the rapid replacement of the plate frame structure without affecting the performance of other parts of the battery stack. The structure of multiple plate frames is uniform, the stacking process is simple, no complex assembly and adjustment are required, and combined with the efficient processing method of the plate frames themselves, the overall production efficiency of the battery stack is improved.

[0079] A fourth aspect of the present invention provides a method for processing a battery stack as described above, comprising: Multiple flow battery stacks are stacked using a plate-and-frame structure; Current is passed through the metal electrodes pre-embedded in the plate frame base 100 of the multiple flow battery stack plate frame structures and connected to the external circuit to melt the electrothermal sealing ring 102 so that two adjacent flow battery stack plate frame structures are stacked and connected. Pressure is applied to the molten electrothermal sealing ring 102 and then cooled to fuse adjacent electrothermal sealing rings 102 together.

[0080] According to the battery stack processing method described above, provided in the fourth aspect of the present invention, electrofusion melting enables the electrothermal sealing rings 102 of adjacent plates and frames to achieve molecular-level fusion. Pressure cooling further ensures the tightness of the sealing layer, completely eliminating assembly gaps or microscopic leakage channels present in traditional sealing methods, and significantly reducing the risk of electrolyte leakage. The fusion structure of the double sealing rings effectively blocks leakage paths from both the periphery and the core area, providing a durable and stable sealing effect that meets the stringent sealing requirements of long-term operation of flow battery stacks. The fused plate and frame structure forms a robust integrated whole with high connection strength, capable of withstanding pressure, vibration, and temperature fluctuations during stack operation, avoiding sealing failures or structural instability caused by loosening of traditional bolted connections. The integrated structure also ensures the dimensional stability of the internal flow channels and reaction areas of the stack, resulting in uniform electrolyte distribution and ensuring stable electrochemical performance of the stack.

[0081] The processing method for a flow battery stack provided in the fourth aspect of the present invention achieves an integrated sealed connection of multiple plate and frame structures through three core processes: stacking, electrofusion melting, and pressurized cooling.

[0082] First, multiple fabricated flow battery stacks are stacked sequentially along a predetermined axis using a plate-and-frame structure. During stacking, it is ensured that the plate-and-frame base 100 of each plate-and-frame is precisely aligned, and the electrofusion sealing rings 102 of adjacent plates-and-frames (including the first sealing ring 104 and the second sealing ring 106) are tightly fitted without offset or gaps. The stacking order of the plates-and-frames is arranged according to the assembly requirements of the battery stack, ensuring that the electrolyte reaction area, flow channel area, and sealing area correspond one-to-one. Positioning pins or guide structures can be used to assist in positioning during stacking, ensuring the coaxiality and flatness of multiple plates-and-frames, providing a precise structural foundation for subsequent melting and fusion.

[0083] Secondly, after stacking, the external circuit is connected to the metal electrodes pre-embedded in the plate frame substrate 100 to form a complete conductive circuit. A preset current is passed through the metal electrodes via the external circuit. After the current flows through the metal electrodes, the plate frame substrate 100 and the electrothermal sealing ring 102 are heated by the Joule heating principle. Since the melting point of the material of the electrothermal sealing ring 102 is lower than that of the first thermoplastic material of the plate frame substrate 100, the heat is preferentially applied to the electrothermal sealing ring 102, causing it to gradually heat up to a molten state.

[0084] Secondly, after the electrothermal sealing ring 102 is completely melted, a preset pressure is applied to the stacked plate and frame structure through an external pressurizing device. The pressure direction is consistent with the stacking direction to ensure that the molten sealing rings of adjacent plates and frames are in full contact and penetrate, eliminating micro gaps. The pressure is kept stable during the pressurization process, so that the molten sealing rings form a dense sealing layer under the pressure.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A plate-and-frame structure for a flow battery stack, characterized in that, include: Plate frame substrate (100) and electrofusion sealing ring (102); The plate frame base (100) and the electrothermal sealing ring (102) are integrally formed by a two-color injection molding process.

2. The plate-and-frame structure for a flow battery stack according to claim 1, characterized in that, The plate frame substrate (100) is made of a first thermoplastic material.

3. The plate and frame structure for a flow battery stack according to claim 1, characterized in that, The electrothermal sealing ring (102) is made of a conductive thermoplastic material, which heats up to a molten state when electricity is applied; Alternatively, the electrothermal sealing ring (102) may be made of a second thermoplastic material and have an independent heating wire built in, which heats the electrothermal sealing ring (102) to a molten state when energized; Alternatively, the electrothermal sealing ring (102) may be made of a second thermoplastic material and have a built-in induction circuit. When subjected to an external magnetic field, it generates eddy currents to heat the electrothermal sealing ring (102) to a molten state.

4. The plate and frame structure for a flow battery stack according to claim 3, characterized in that, The electrothermal sealing ring (102) includes: A first sealing ring (104) is provided along the circumference of the plate frame base (100); The second sealing ring (106) is disposed along the electrolyte reaction area and electrolyte flow channel area on the plate frame substrate (100).

5. The plate and frame structure for a flow battery stack according to claim 4, characterized in that, The plate frame base (100) is provided with a first sealing groove (108) and a second sealing groove (110), the first sealing ring (104) is provided in the first sealing groove (108), and the second sealing ring (106) is provided in the second sealing groove (110). Metal wire circuits are pre-embedded in the first sealing ring (104) and the second sealing ring (106).

6. A method for fabricating a plate-and-frame structure for a flow battery stack as described in any one of claims 1 to 5, characterized in that, include: The first injection molding is performed using a first thermoplastic material to form a plate-frame matrix (100). The electrothermal sealing ring (102) is formed by a second injection molding of a conductive thermoplastic material or a second thermoplastic material onto the plate frame substrate (100).

7. The fabrication method of the plate and frame structure for a flow battery stack according to claim 6, characterized in that, The melting point of the conductive thermoplastic material and the melting point of the second thermoplastic material are lower than the melting point of the first thermoplastic material.

8. The method for processing the plate frame for the battery stack according to claim 6 or 7, characterized in that, The electrothermal sealing ring (102) includes a first sealing ring (104) and a second sealing ring (106). The injection molding temperature of the first sealing ring (104) is 275 degrees Celsius to 285 degrees Celsius, and the injection molding temperature of the second sealing ring (106) is 315 degrees Celsius to 325 degrees Celsius.

9. A flow battery stack, characterized in that, The plate and frame structure for flow battery stacks as described in any one of claims 1 to 5 includes multiple stacked configurations.

10. A method for processing a flow battery stack as described in claim 9, characterized in that, include: Multiple flow battery stacks are stacked using a plate-and-frame structure; Current is passed through the metal electrodes pre-embedded in the plate frame base (100) of the multiple flow battery stack plate frame structures and connected to the external circuit, melting the electrothermal sealing ring (102) so that two adjacent flow battery stack plate frame structures are stacked and connected. Pressure is applied to the molten electrofusion seal ring (102) and cooled to fuse adjacent electrofusion seal rings (102) together.

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