Liquid flow pile structure with few sealing interfaces and process

Abstract

The invention discloses a liquid flow galvanic pile structure with few sealing interfaces, which comprises a plurality of galvanic pile groups which are sequentially stacked and compounded into an integrated structure according to a proton membrane unit, a carbon felt and a bipolar plate unit, and all the units in the galvanic pile combined structure are fused and connected into the integrated structure without gaps, so that leakage surfaces among the units are avoided, and the sealing performance of the galvanic pile is improved. Leakage is effectively prevented, the number of parts is reduced, and installation is simplified. And the galvanic pile combination is combined by adopting an ultrasonic or laser welding process mode, and the sealing materials of the welded sealing sheet, the proton unit and the bipolar plate unit are the same material, so that the fusion characteristic is realized, the complete fusion of welding combination is ensured, the leakage risk is small, and the installation is reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow batteries, and in particular to a liquid flow battery stack structure and process with fewer sealing interfaces. Background Art

[0002] Liquid flow batteries are a type of electrochemical energy storage technology that generally utilizes the changes in the valence state of active substances in the positive and negative liquid phases during the charge and discharge process to achieve energy storage and release. Liquid flow batteries are usually assembled in a stacked filter press assembly, that is, the key components such as bipolar plates, frames, carbon felt, proton membranes, and sealing gaskets are stacked. In order to ensure that the electrolyte does not leak, the edges of all the above components that are in contact must be sealed.

[0003] The publication number is CN101651220A, and the patent name is a highly sealed liquid flow battery, which provides a liquid flow battery integrated device, including a negative electrode liquid flow frame, a negative electrode, a proton exchange membrane, a positive electrode, and a positive electrode liquid flow frame connected in sequence, the proton exchange membrane and the liquid flow frame are bonded by an acid-resistant adhesive, and the positive electrode and the proton exchange membrane and the negative electrode and the proton exchange membrane are bonded together by conductive glue. Since the present invention integrates the proton exchange membrane with the liquid flow frame and the electrode on both sides by a bonding method, the battery assembly process is simplified and the sealing of the battery is improved. At the same time, the integration of the membrane and the electrode reduces the contact resistance therebetween, thereby reducing the internal resistance of the battery and improving the battery efficiency.

[0004] Use conductive glue to completely overlap and bond the outer edge of the proton exchange membrane with the outer edge of the liquid flow frame to achieve the effect of battery sealing. Since installing the ion exchange membrane in a dry state is prone to water absorption and swelling, which makes the seal between the ion exchange membrane and the electrode frame fail, the ion exchange membrane of the liquid flow battery is often treated with a solution and installed in a wet state. The ion exchange membrane in a wet state needs to be strictly sealed inside the battery stack, and usually the whole needs to be compressed and sealed by the pre-tightening force of the screw and the spring. Once the pre-tightening force decays, the battery stack is prone to electrolyte leakage.

[0005] In addition, the number of components in a multi-stack assembly increases exponentially, making installation complex and detrimental to production efficiency. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a liquid flow battery stack structure and process with fewer sealing interfaces, which can reduce the number of components and simplify the installation process. The obtained liquid flow battery stack has a low leakage risk and reliable installation.

[0007] In order to solve the above technical problems, the present invention solves the problems through the following technical solutions: a liquid flow stack structure with few sealing interfaces, including a stack group composed of a plurality of proton membrane units, carbon felt and bipolar plate units stacked in sequence to form an integrated structure, the proton membrane unit including a proton membrane sealing sheet that is symmetrical with the proton membrane as the center and compounded on the two bonding surfaces of the proton membrane, and a fusion connection structure with no layer gap is formed between the proton membrane sealing sheet and the contact surface of the proton membrane, the bipolar plate unit includes a surrounding frame and a sealing sheet that are symmetrically compounded on the two working surfaces of the bipolar plate substrate in sequence with the bipolar plate substrate as the center, and a fusion connection structure with no layer gap is formed between the connecting surfaces of the surrounding frame, the sealing sheet and the bipolar plate substrate.

[0008] In the above technical solution, the middle part of the proton membrane sealing sheet is a hollow structure, which is compounded on the bonding surface of the proton membrane to form a frame-type sealing structure.

[0009] In the above technical solution, the bipolar plate substrate is formed by molding and fusing a resin layer and a graphite fusion layer.

[0010] In the above technical solution, the bipolar plate substrate and the surrounding frame are both formed by high-temperature molding and fusion of expanded graphite and resin composite materials, and are integrally provided with flow channels interconnected with the flow channel holes.

[0011] In the above technical solution, the flow channel includes an inlet and an outlet, and a plurality of interconnected meandering flow channels are arranged between the inlet and the outlet.

[0012] In the above technical solution, the surrounding frame is a hollow structure in the middle, which is combined with the expanded graphite and resin fusion layer to form a structure with a reaction space in the middle, and a sealing surface is established at the non-hollow part of the surrounding frame.

[0013] In the above technical solution, the sealing surface is provided with a sealing structure other than a plane, including a sealing structure with convex edges or tooth-like protrusions.

[0014] In the above technical solution, the sealing sheet and the proton membrane sealing sheet are both hot-melt material layers.

[0015] In the above technical solution, the hot-melt material is a fluorine-based resin, including PP, PE, HDPE, PTFE and all fluorine-based resins.

[0016] A manufacturing process of a liquid flow battery stack structure with fewer sealing interfaces, characterized by comprising the following steps: Step 1: Compounding the proton membrane unit, stacking the proton membrane sealing sheet, the proton membrane and the proton membrane sealing sheet in sequence and then hot pressing them to melt and compound the three together to obtain the proton membrane unit; Step 2: Bipolar plate production, A. Expansion, after oxidation intercalation, natural flake graphite is expanded at high temperature to obtain expanded graphite worms, and the expansion temperature is controlled to be 900℃~1200℃; B. Fabrication, the prepared expanded graphite worms are settled to the wind control fabrication channel, and the temperature of the fluffy worms is controlled to be 20~40℃ by hot air stirring; C. Mixing, the resin is evenly sprayed on the graphite worms by dry compressed air and mixed evenly; D. Pressing, the mixed graphite worms are rolled by a roller to obtain the bipolar plate substrate; E. Channel forming, by a forming machine and a mold The bipolar plate raw material is pressed to form a flow channel, which is the bipolar plate substrate; at the same time, the bipolar plate substrate raw material is molded into a frame; F. Combination and curing, stacking the sealing layer, frame, substrate, frame, and sealing layer in sequence into a complete structure, and then hot pressing and curing in a mold to obtain an integrally formed graphite-based multifunctional bipolar plate, with the temperature controlled at 170°C~250°C and the time being 5-30 minutes; Step three: Stacking the proton membrane unit, carbon felt and bipolar plate unit in sequence for several groups, and then using laser or ultrasonic welding as a combination process of fusion connection structure to form a stack structure.

[0017] The welding sealing surface, the sealing materials of the integrated proton unit and the integrated bipolar plate unit are the same material with the property of being compatible. Through laser or ultrasonic thermal management technology, they are completely integrated into one. The fusion position can be on the front side of the contact surface and can also include the side edge joint.

[0018] Compared with the prior art, the present invention has the following beneficial effects: by realizing a gapless fusion-connected integrated structure for each unit in the battery stack combination structure, leakage surfaces between the units are eliminated, which is also beneficial to reducing the number of parts and simplifying installation; and the multi-battery stack combination is combined by ultrasonic or laser welding technology, with low leakage risk and reliable installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of the present invention.

[0021] Figure 2 Schematic diagram of the splitting of the proton membrane unit in the unbound state.

[0022] Figure 3 Schematic diagram of the bipolar plate unit structure.

[0023] Figure 4This is a schematic diagram of a flow channel structure arranged in the reaction area of ​​a bipolar plate.

[0024] Figure 5 This is a schematic diagram of the disassembly of the bipolar plate unit structure in the uncombined state. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings.

[0026] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be used for other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0027] Those skilled in the art should understand that, in the disclosure of the present invention, the directions or positions indicated by the terms "longitudinal", "lateral", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, which are only simplified descriptions for the convenience of describing the present invention, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the above terms should not be understood as limitations on the present invention.

[0028] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0029] See also Figures 1 to 5 A liquid flow battery stack structure with few sealing interfaces includes a battery stack group composed of a plurality of proton membrane units 1, carbon felt 2 and bipolar plate units 3 stacked in sequence to form an integrated structure.

[0030] The proton membrane unit 1 includes a proton membrane sealing sheet 12 which is symmetrical with the proton membrane 11 as the center and is compounded on the two bonding surfaces of the proton membrane 11. The structural dimensions of the proton membrane 11 and the proton membrane sealing sheet 12 match each other. The middle part of the proton membrane sealing sheet 12 is a hollow structure, so that the proton membrane 11 can form a proton exchange channel in the middle part, and the frame-type sealing structure compounded on the bonding surface of the proton membrane 11 is conducive to sealing. Moreover, since the proton membrane sealing sheets 12 are all hot-melt material layers, after hot pressing and compounding, the contact surfaces of the proton membrane sealing sheet 12 and the proton membrane 11 can be fused with each other to form a combination without layer gaps, effectively preventing sealing failure caused by stratification. Of course, flow channel holes 4 for fluid to pass are correspondingly arranged on the proton membrane sealing sheet 12 and the proton membrane 11.

[0031] The bipolar plate unit 3 includes a bipolar plate substrate 31, a frame 32 and a sealing sheet 33. Of course, since the frame 32 and the sealing sheet 33 are symmetrically composited on the two working surfaces of the bipolar plate substrate 31 with the bipolar plate substrate 31 as the center, two groups of sealing sheets 33 are provided. The frame 32 is located on the two working surfaces of the bipolar plate substrate 31. It is worth mentioning that the bipolar plate substrate 31 is formed by the fusion of expanded graphite and resin, and the frame 32 is also formed by hot molding of the material fused with expanded graphite and resin. Moreover, the frames 32 on both sides are the materials fused with expanded graphite and resin. The material of the frame 32 and the bipolar plate 31 is consistent, reducing the stratification. At the same time, one material is used to realize two structures, and high-temperature molding and fusion are formed at one time, reducing material costs and simplifying the process. After hot molding, the contact surfaces are fused with each other after the resin is hot-melted to form an integrated structure without layer gaps, which is not only conducive to simplifying the processing technology, but also eliminates the leakage surface between them and improves the sealing performance. The frame 32 is a hollow structure in the middle, forming a structure with a reaction space in the middle, and a sealing surface is established at the non-hollow part of the frame 32 to cooperate with the sealing sheet 33. Since the sealing sheet 33 is a hot-melt material layer, it can be a resin PP, PE, HDPE, PTFE and all fluorine resins. Therefore, after hot pressing and compounding, the contact surfaces of the sealing sheet 33 and the frame 32 can be fused with each other to form a combination without layer gaps, effectively preventing sealing failure caused by stratification.

[0032] Of course, in order to provide a fusion effect, a sealing structure including ridges or tooth-like protrusions may be provided on the sealing surface in addition to the flat surface, which can promote sealing.

[0033] At the same time, in order to make the reaction more uniform, the graphite fusion layer in the reaction space in the middle of the frame 32 is integrally provided with a flow channel interconnected with the flow channel hole 4 on the resin layer, the flow channel includes an inlet and an outlet, and a plurality of interconnected meandering flow channels 311 are arranged between the inlet and the outlet. Since the graphite resin fusion material has plasticity, the flow channel arranged in the reaction area is not limited to the meandering flow channel 311, and it can also be a planar structure or a concave-convex structure flow channel, and the flow channel structure size can be diversified to meet a variety of design and performance requirements.

[0034] The specific manufacturing process of the above structure includes the following steps: Step 1: Compounding the proton membrane unit, stacking the proton membrane sealing sheet, the proton membrane and the proton membrane sealing sheet in sequence and then hot pressing them to melt and compound the three together to obtain the proton membrane unit; Step 2: Bipolar plate production, A. Expansion, after oxidation and intercalation of natural flake graphite, expand it at high temperature to obtain expanded graphite worms, and control the expansion temperature to 900℃~1200℃; B. Fabrication, the prepared expanded graphite worms are settled to the wind control fabrication channel, and hot air is used to stir, and the temperature of the fluffy worms is controlled at 20~40℃; C. Mixing, use dry compressed air to spray the resin evenly on the graphite worms and mix them evenly; D. Pressing, the mixed graphite worms are rolled by a roller to obtain the bipolar plate raw material. E. Flow channel forming, the molding machine and the mold press the bipolar plate raw material into the flow channel, which is the substrate; at the same time, the bipolar plate raw material is molded into a frame; F. Combined curing, the sealing layer, frame, substrate, frame, and sealing layer are stacked in sequence into a complete structure, and then hot-pressed and cured in the mold to obtain an integrally formed graphite-based multifunctional bipolar plate. Control the temperature at 170℃~250℃ for 5-30 minutes; Step 3: Compound the stack, stack several groups of proton membrane units, carbon felt and bipolar plate units in order, and use laser or ultrasonic welding as a combination process of fusion connection structure to make the stack structure. The sealing surface of the weld, the sealing materials of the integrated proton unit and the integrated bipolar plate unit are the same material and have the property of melting. Through laser or ultrasonic thermal management technology, let it completely merge into one. The fusion position can be on the front of the contact surface and can also include the side edge joint.

[0035] Through the above process, the product performance obtained is as follows: (taking the all-vanadium electrolyte stack as an example) Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A liquid flow stack structure with few sealing interfaces, characterized in that: The invention comprises a stack group composed of a plurality of proton membrane units (1), carbon felt (2) and bipolar plate units (3) stacked in sequence to form an integrated structure, wherein the proton membrane unit (1) comprises a proton membrane sealing sheet (12) symmetrically composited with the proton membrane (11) at the center and composited with two bonding surfaces of the proton membrane (11), and a fusion connection structure without a layer gap is formed between the contact surface of the proton membrane sealing sheet (12) and the proton membrane (11); the bipolar plate unit (3) comprises a surrounding frame (32) and a sealing sheet (33) symmetrically composited with the two working surfaces of the bipolar plate substrate (31) at the center, and a fusion connection structure without a layer gap is formed between the connecting surfaces of the surrounding frame (32), the sealing sheet (33) and the bipolar plate substrate (31).

2. The liquid flow battery stack structure with few sealing interfaces according to claim 1, characterized in that: The middle portion of the proton membrane sealing sheet (12) is a hollow structure, and is composited on the bonding surface of the proton membrane (11) to form a frame-type sealing structure.

3. The liquid flow battery stack structure with few sealing interfaces according to claim 1, characterized in that: The bipolar plate substrate (31) is formed by molding and fusing a resin layer and a graphite fusion layer.

4. The liquid flow battery stack structure with few sealing interfaces according to claim 3, characterized in that: The bipolar plate substrate (31) and the surrounding frame (32) are both formed by high-temperature molding fusion of expanded graphite and a resin composite material, and are integrally provided with a flow channel interconnected with the flow channel hole.

5. The liquid flow battery stack structure with fewer sealing interfaces according to claim 4, characterized in that: The flow channel comprises an inlet and an outlet, and a plurality of interconnected meandering flow channels (311) are arranged between the inlet and the outlet.

6. The liquid flow battery stack structure with fewer sealing interfaces according to claim 5, characterized in that: The surrounding frame (32) is a hollow structure in the middle, and is composited with the expanded graphite and resin fusion layer to form a structure with a reaction space in the middle, and a sealing surface is established at a non-hollow portion of the surrounding frame (32).

7. The liquid flow battery stack structure with few sealing interfaces according to claim 6, characterized in that: The sealing surface is provided with a sealing structure other than the plane.

8. The liquid flow battery stack structure with few sealing interfaces according to claim 2, characterized in that: The sealing sheet (33) and the proton membrane sealing sheet (12) are both hot-melt material layers.

9. The liquid flow battery stack structure with few sealing interfaces according to claim 8, characterized in that: The hot melt material includes PP, PE, HDPE, PTFE and fluorine resin.

10. The manufacturing process of a liquid flow battery stack structure with few sealing interfaces according to claim 1, characterized in that: The steps include: Step 1: Compounding the proton membrane unit, stacking the proton membrane sealing sheet, the proton membrane and the proton membrane sealing sheet in sequence and then hot pressing them to melt and compound the three together to obtain the proton membrane unit; Step 2: Bipolar plate production, A. Expansion, after oxidation intercalation, natural flake graphite is expanded at high temperature to obtain expanded graphite worms, and the expansion temperature is controlled to be 900℃~1200℃; B. Fabrication, the prepared expanded graphite worms are settled to the wind control fabrication channel, and hot air is used for stirring to control the temperature of the fluffy body worms at 20~40℃; C. Mixing, the resin is evenly sprayed on the graphite worms using dry compressed air and mixed evenly; D. Pressing: The mixed graphite worms are rolled by a pressure roller to obtain the bipolar plate substrate raw material; E. Flow channel forming: The bipolar plate raw material is pressed into a flow channel by a molding machine and a mold, which is the bipolar plate substrate; at the same time, the bipolar plate substrate raw material is molded into a frame; F. Combination and curing: The sealing layer, the frame, the substrate, the frame, and the sealing layer are stacked in sequence into a complete structure, and then hot-pressed and cured in a mold to obtain an integrally formed graphite-based multifunctional bipolar plate, with the temperature controlled at 170°C~250°C and the time being 5-30 minutes; Step three: Stack assembly: After stacking several groups in the order of proton membrane units, carbon felt and bipolar plate units, a stack structure is made using a combination process of laser or ultrasonic welding as a fusion connection structure.

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