A manufacturing method for a flow field plate of a flow battery

Abstract

This invention relates to a method for manufacturing a flow battery runner plate. The method primarily employs a side-feed molding process, where molten adhesive is poured into the center of a flow channel section within the runner plate in the mold. After the molten adhesive enters the center of the flow channel section, it flows horizontally in a cross direction to fill the mold cavity, with the injection point located on the inner end face of the flow channel section, thus forming the runner plate. This injection molding method allows for mass production of the runner plate, effectively reducing manufacturing costs, ensuring the strength of the runner plate, and guaranteeing its sealing during assembly, thereby enhancing its overall practicality and functionality.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a flow channel plate for a flow battery, and more particularly to a method for mass-producing flow channel plates using injection molding. This method not only effectively reduces manufacturing costs, but also ensures the strength of the flow channel plate and its sealing performance during assembly, thereby enhancing its overall practicality and functionality. Prior Technology

[0002] Note that with the development of renewable energy, these intermittent and uncertain power generation energy sources must be efficiently allocated and dispatched through energy storage technology. Storing renewable energy in energy storage batteries to solve the problem of electricity demand is currently the most important issue. Among them, redox flow batteries (RFB) are regarded as one of the new energy storage battery systems with great development potential. It is an energy storage battery with long life, high safety and flexible design. It achieves the purpose of storing energy by using a full vanadium electrolyte to flow through the electrode reaction zone in the battery to carry out redox reaction.

[0003] A flow battery is an electrochemical energy storage device. A flow battery system consists of an electrolyte storage tank, a battery stack, and a pump for electrolyte circulation. The system's energy storage capacity is determined by the electrolyte storage tank, while the power generation capacity is determined by the battery stack, thus offering flexible system configuration. During operation, the pump delivers the electrolyte from the storage tank to the battery stack, where it undergoes charging and discharging via redox reactions. The most important reactive components of the battery consist of bipolar plates at both ends, which serve as the external support structure for each individual cell and separate the positive and negative electrolytes of adjacent cells. The area inside each bipolar plate is called a "single cell." A membrane separates the positive and negative electrodes within the single cell. Porous electrodes within these electrodes provide the sites for the redox reactions of the electrolyte. To stabilize and support the various reaction components inside the flow battery, the design uses two frames on the outside of the battery to clamp the bipolar plates, called "battery frames". A mass membrane is pressed together by the two battery frames to form an effective single-cell structure. In order to prevent electrolyte leakage in the battery, the design uses a sealant to clamp the mass membrane to achieve the sealing condition, and finally it is locked with bolts and other fasteners.

[0004] In the design of the battery frame structure, when using two frame plates to clamp the bipolar plates, a seal is used on the mating surface to prevent electrolyte leakage through the gaps. The seal must be designed with corresponding grooves (groove depth approximately 1.5mm) and a flow channel is designed on the other side. This limits the thickness of the frame plates to 5mm (the thickness of commercially available flow batteries). Finally, bolt fasteners are used to secure the stack, which can lead to uneven force application at each fastening point, causing stress concentration and causing critical modules to crack and damage the stack. Commercial flow battery stacks are mostly designed with 20 to 40 battery modules connected in series to achieve an operating voltage of approximately 32 to 64V (single cell rated voltage 1.26V, maximum voltage 1.6V). If a stack of 40 batteries connected in series is required, at least 80 battery frame plates are needed, thus increasing the manufacturing cost of flow batteries. By investing in mass-production-ready mold development and manufacturing technologies, the production cost of battery frames can be effectively reduced, thereby lowering the manufacturing cost of battery stacks. Domestic and international research projects and related technology developments have explored a mold design approach that utilizes injection molding of frame components to manufacture an integrated frame from graphite sheets. Literature has proposed using mold flow analysis technology to frame and inject graphite sheets based on the location and dimensions of the injection molding runner, achieving the development of an integrated battery frame. However, the injection-molded sheet thickness is 5mm, making the battery frame relatively thick compared to the technical dimensions. This leads to plastic shrinkage during molding and cooling; in the literature, the shrinkage at the rounded corners is approximately 4mm. Furthermore, residual stress and shrinkage during molding can cause gaps between the two materials, resulting in internal leakage between the positive and negative electrodes of the battery.

[0005] Therefore, based on the above, the inventor, drawing on years of rich design, development and practical manufacturing experience in the related industry, has researched and improved upon the existing shortcomings to provide a method for manufacturing flow battery channel plates, aiming to achieve better practical value. Summary of the Invention

[0006] The main objective of this invention is to provide a method for manufacturing flow channel plates for flow batteries. The method mainly utilizes injection molding to mass-produce flow channel plates, which can not only effectively reduce manufacturing costs, but also ensure the strength of the flow channel plates and the sealing of the flow channel plates during assembly, thus increasing their practicality in overall use.

[0007] The main objective and effect of the method for manufacturing the flow channel plate of the flow battery of the present invention are achieved by the following specific technical means:

[0008] The main method is to use a side-feeding molding method, in which molten glue is poured from the center of the liquid flow channel in the middle of the runner plate in the mold. After the molten glue enters the center of the liquid flow channel, it is then allowed to flow horizontally in a cross direction to fill the mold cavity, so that the glue entry point is located on the inner end face of the liquid flow channel, thus forming the runner plate.

[0009] In a preferred embodiment of the method for manufacturing a flow battery channel plate of the present invention, the injection time of the side-shaped injection is 3.857 seconds.

[0010] In a preferred embodiment of the method for manufacturing a flow battery channel plate of the present invention, the cooling time required for the side-mounted injection mold temperature to cool the molten material to the ejection temperature is 65.52 seconds.

[0011] In a preferred embodiment of the method for manufacturing a flow battery channel plate of the present invention, the warpage of the flow plate formed by side injection molding reaches a maximum of 0.3894 mm. Simple Explanation of the Diagram

[0012] Figure 1: Schematic diagram of the three-dimensional structure of the side-feeding molding state of the present invention Figure 2: Top view of the side-feeding molding state of the present invention Figure 3: Schematic diagram of the three-dimensional structure of the point-like injection molding state of the present invention Figure 4: Schematic diagram of the three-dimensional structure of the film-like casting molding state of the present invention. Figure 5: Comparative Analysis of the Invention (I) Figure 6: Comparative Analysis of the Invention (II) Implementation

[0013] To provide a more complete and clear disclosure of the technical content, purpose, and effects achieved by this invention, a detailed description is provided below, along with reference to the accompanying drawings and figures:

[0014] Firstly, since different runner designs within the mold directly affect the generation and distribution of weld lines, and indirectly affect the structural strength of the formed runner plate, this invention primarily focuses on testing runner plate casting and molding using three runner designs: side-gating, point-gating, and film-gating.

[0015] The side-mounted gating:

[0016] Please refer to the first figure, which is a three-dimensional structural diagram of the side-feeding molding state of the present invention, and the second figure, which is a top view structural diagram of the side-feeding molding state of the present invention. The molten glue is poured from the center position of the liquid flow groove (11) opened in the middle of the runner plate (1) in the mold. After the molten glue enters the center position of the liquid flow groove (11), the molten glue is then allowed to flow horizontally in a cross direction to fill the mold cavity, so that the glue entry point is located on the inner end face of the liquid flow groove (11), thereby forming the runner plate (1).

[0017] If the injection time of the molten material in the side-gated injection is too short or too long, the pressure drop when filling the cavity will increase. Therefore, the range with the lowest pressure drop is the optimal injection time. The final injection time is 3.857 seconds, and the cooling time required for the molten material to cool to the ejection temperature is 65.52 seconds. The maximum warpage is 0.3894 mm.

[0018] The point-like injection:

[0019] Please also refer to the third figure, which shows the three-dimensional structure of the point-like injection molding state of the present invention. The molten glue is injected from above the center position of the liquid flow groove (11) opened in the middle of the runner plate (1) in the mold. After the molten glue enters above the center position of the liquid flow groove (11), the molten glue first flows in a cross direction, and then the molten glue flowing in a cross direction flows downward to fill the mold cavity, so that the glue entry point is located at the upper edge of the periphery of the liquid flow groove (11), and the runner plate (1) is formed.

[0020] If the injection time of the molten material in the point injection is too short or too long, the pressure drop when filling the cavity will increase. Therefore, the range with the lowest pressure drop is the optimal injection time. The final analysis shows that the injection time is 3.88 seconds, and the cooling time required for the molten material to cool to the ejection temperature is 67.51 seconds. The maximum warpage is 0.8368 mm.

[0021] The membrane-like inlet:

[0022] Please also refer to Figure 4, which shows the three-dimensional structure of the film-like casting molding state of the present invention. The molten adhesive is poured from the center of the liquid flow channel (11) in the middle of the runner plate (1) in the mold. After the molten adhesive enters the center of the liquid flow channel (11), the molten adhesive flows to both sides in a planar shape to fill the mold cavity. The injection point is located on the inner end face of both sides of the liquid flow channel (11) to form the runner plate (1).

[0023] If the injection time of the molten material in the film-like injection is too short or too long, the pressure drop in filling the cavity will increase. Therefore, the range with the lowest pressure drop is the optimal injection time. The final analysis shows that the injection time is 6.717 seconds, and the cooling time required for the mold temperature to cool the molten material to the ejection temperature is 68.03 seconds, with a maximum warpage of 0.9345 mm.

[0024] Thus, based on the above explanation, a comparison of the three casting methods—side casting, point casting, and film casting—is presented. Please also refer to Figure 5, the comparative analysis diagram (I) of this invention. When the runner plate (1) is used for side casting, the cooling time is the shortest; for point casting, the cooling time is second; and for film casting, the cooling time is the longest. Conversely, when the runner plate (1) is used for side casting, the injection time is the lowest; for point casting, the injection time is second; and for film casting, the injection time is the highest. Please also refer to Figure 6, the comparative analysis diagram (II) of this invention. When the runner plate (1) is used for side casting, the warping is the lowest; for point casting, the warping is second; and for film casting, the warping is the highest.

[0025] Furthermore, since the runner plate (1) is made up of multiple pieces stacked together during use, if the glue inlet of the runner plate (1) is located on both ends of the runner plate (1) during the manufacturing process, the glue inlet will protrude from the surface of the runner plate (1), causing the runner plates (1) to not fit tightly when stacked together. The protrusion formed by the glue inlet needs to be treated separately, which not only causes great inconvenience in the overall manufacturing process, but also easily affects the relationship between the runner plates (1). Sealing effect; Of the three casting methods mentioned above, the side casting, the point casting, and the film casting have the following advantages: Since the glue entry point of the point casting is located at the upper periphery of the liquid flow channel (11), the glue entry point of the point casting method needs to be further processed in order to achieve a tight fit when the flow channel plate (1) is stacked and bonded. The side casting and film casting methods, which have the glue entry point located on the inner end face of the liquid flow channel (11), are superior to the point casting method.

[0026] Therefore, it can be clearly seen from the above comparison that when the runner plate (1) is manufactured by side injection, it has the lowest cooling time, injection time and warpage, which allows the runner plate (1) to be filled earlier and flatter, and can shorten the process time and improve production efficiency.

[0027] Based on the above description of the structure and usage of the present invention, it can be seen that, compared with the existing structure, the present invention mainly utilizes injection molding to mass-produce runner plates, which can not only effectively reduce manufacturing costs, but also ensure the strength of the runner plates and the sealing of the runner plates during assembly, thus increasing its practicality and functionality in overall use.

[0028] However, the foregoing embodiments or figures are not intended to limit the product structure or usage of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

[0029] In conclusion, the embodiments of the present invention can indeed achieve the expected effects, and the specific structure disclosed therein has not only never been seen in similar products, but has also not been disclosed before the application. It fully complies with the provisions and requirements of the Patent Law. Therefore, we hereby file an application for an invention patent and respectfully request your review and grant of a patent, which would be of great benefit.

[0030] 1: Flow channel plate 11: Liquid flow tank section

Claims

1. A method for manufacturing a flow battery runner plate, which mainly involves a side-feeding molding method, in which molten adhesive is poured from the center of a flow channel section opened in the middle of the runner plate in the mold. After the molten adhesive enters the center of the flow channel section, it is then allowed to flow horizontally in a cross direction to fill the mold cavity, with the entry point located on the inner end face of the flow channel section, thereby forming the runner plate.

2. The method for manufacturing the flow battery channel plate as described in claim 1, wherein, The injection time for this side-mounted injection is 3.857 seconds.

3. The method for manufacturing the flow battery channel plate as described in claim 1, wherein, The required cooling time for the molten material to cool to the ejection temperature using the mold temperature for side-entry injection is 65.52 seconds.

4. The method for manufacturing a flow battery channel plate as described in claim 1, wherein, The maximum warpage of the runner plate formed by the side injection molding is 0.3894 mm.

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