Conductive bipolar plate with flow channels for flow batteries and methods of making

Abstract

This invention discloses a conductive bipolar plate with flow channels for flow batteries, comprising a cut and shaped carbon fiber felt, with symmetrical upper and lower flow channels at both ends of the cut and shaped carbon fiber felt. The outer surface of the cut and shaped carbon fiber felt is coated with a conductive plastic material, which is a mixture of conductive filler and polymer resin. The invention also discloses a method for preparing the conductive bipolar plate. This invention is applicable to the field of electrochemical batteries, with a simple process and stable and reliable technology, suitable for large-scale industrial production. The flow channels on the conductive bipolar plate can uniformly distribute the electrolyte on the electrodes, improving the utilization efficiency of the electrolyte and thus increasing the battery output power.

Description

Technical Field

[0001] This invention relates to the field of electrochemical batteries, and more particularly to a conductive bipolar plate with flow channels for flow batteries and its preparation method. Background Technology

[0002] With increasingly severe environmental pollution, reducing the use of traditional fossil fuels such as coal and oil has become a crucial issue for countries worldwide. Improving the utilization rate of renewable energy has become a primary means of improving the natural environment and meeting the needs of normal human production and daily life. Flow batteries, as a safe, reliable, and low-cost large-scale energy storage method, have become a focus of attention for engineers in the field of energy conservation and emission reduction.

[0003] Flow batteries achieve the interconversion of electrical and chemical energy through redox reactions between ions of different valence states, thus storing and releasing energy. They offer advantages such as fast response, shock resistance, long service life, high energy efficiency, and low overall cost. The bipolar plate is a key component of a flow battery, primarily serving to: connect the positive and negative electrodes and facilitate current transfer between different individual cells; prevent the mixing of vanadium electrolytes of different valence states on both sides; and support components such as the ion exchange membrane and graphite felt electrodes. The bipolar plate also allows the carbon felt electrode to spread smoothly on the plate, increasing the reaction area and improving reaction efficiency.

[0004] However, with the significant increase in the power and current density of flow batteries, the requirements for uniform electrolyte distribution are becoming increasingly stringent. Uneven distribution will greatly affect battery performance. Therefore, there is an urgent need to design a conductive bipolar plate that can uniformly distribute the electrolyte on the electrodes, improve electrolyte utilization efficiency, and thus enhance battery performance. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide solutions that overcome or at least partially solve the above problems.

[0006] According to one aspect of the present invention, a conductive bipolar plate with flow channels for a flow battery is provided, comprising a cut and shaped carbon fiber felt, wherein symmetrical upper and lower flow channels are provided at both the upper and lower ends of the cut and shaped carbon fiber felt, and the outer surface of the cut and shaped carbon fiber felt is coated with a conductive plastic material, wherein the conductive plastic material is a mixture of conductive filler and polymer resin.

[0007] Preferably, the cut and shaped carbon fiber felt is formed by a die cutter or cutting equipment, and its thickness is 4~8mm.

[0008] Preferably, the upper and lower flow channels are separated by an intermediate felt with a thickness of 1 mm, a flow channel depth of 1-2 mm, and a width of 1-3 mm.

[0009] Preferably, both the upper and lower flow channels adopt a spiral structure.

[0010] Preferably, the conductive filler is one or more of expanded graphite, flake graphite, carbon black, long carbon fiber, and short carbon fiber.

[0011] Preferably, the polymer resin is one or more of PVDF, PP, PE, and PVC.

[0012] Preferably, in the conductive plastic raw material, the volume percentage of conductive filler is 10% to 50%; and the volume percentage of polymer resin mixture is 20% to 90%.

[0013] Preferably, it also includes a carbon fiber felt cutting mold, which includes an upper cutting mold and a lower cutting mold. The bottom of the upper cutting mold is provided with a cutting tip, and the top of the upper cutting mold is correspondingly offset with a cutting tip.

[0014] On the other hand, a method for preparing a conductive bipolar plate with flow channels for a flow battery includes the following steps: The cut and shaped carbon fiber felt is placed in the injection mold and matches the concave and convex structures in the mold. The upper and lower molds are then closed. The conductive plastic raw material of the formula is injected into the injection mold using injection molding equipment, and then held under pressure to set the shape.

[0015] The conductive bipolar plate with flow channels provided by this invention has a simple process and a stable and reliable technical method, making it suitable for large-scale industrial production. The flow channels on the conductive bipolar plate can make the electrolyte evenly distributed on the electrodes, improving the utilization efficiency of the electrolyte and thus increasing the battery output power.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the conductive bipolar plate provided in an embodiment of the present invention; Figure 2 This is a cross-sectional view of a conductive bipolar plate provided in an embodiment of the present invention; Figure 3 A schematic diagram of a cut and shaped carbon fiber felt structure provided in an embodiment of the present invention. Figure 1 ; Figure 4 A schematic diagram of the carbon fiber felt structure provided in an embodiment of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of an injection mold provided in an embodiment of the present invention; Figure 6 A schematic diagram of a carbon fiber felt cutting mold provided in an embodiment of the present invention; Figure 7 This is a flowchart of the preparation method provided in an embodiment of the present invention. Detailed Implementation

[0019] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0020] The terms "comprising" and "having," and any variations thereof, in the specification, embodiments, claims, and drawings of this invention are intended to cover non-exclusive inclusion, such as including a series of steps or units.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] like Figures 1-6 As shown, a conductive bipolar plate with flow channels uses a pre-cut carbon fiber felt as a support and a mixture of conductive filler and polymer resin as conductive plastic raw material. After being fully mixed, it is formed in an injection mold by injection molding equipment.

[0023] Among them, the cut and shaped carbon fiber felt 1 is formed by processing carbon fiber felt as raw material through a die cutter or cutting equipment.

[0024] The mold is an injection mold, specifically developed for the product, with an internal concave-convex structure that corresponds to and cooperates with the cut and shaped carbon fiber felt.

[0025] In one possible implementation, such as Figure 3 As shown, the cut and shaped carbon fiber felt 1 has spiral flow channels, and the outer surface of the cut and shaped carbon fiber felt 1 is covered with conductive plastic material 8, which is a mixture of conductive filler and polymer resin.

[0026] In one possible implementation, the cut and shaped carbon fiber felt 1 is formed by a die cutter or cutting equipment, and its thickness is 4~8mm.

[0027] In one possible implementation, such as Figure 1 , Figure 2 and Figure 4 As shown, the cut and shaped carbon fiber felt 2 has symmetrical bipolar plate channels 9 at both the upper and lower ends, which are divided into upper and lower channels. The outer surface of the cut and shaped carbon fiber felt 2 is covered with conductive plastic material 8, which is a mixture of conductive filler and polymer resin.

[0028] In one possible implementation, an intermediate felt with a thickness of 1 mm is placed between the upper and lower flow channels, the flow channel depth is 1-2 mm, and the width is 1-3 mm.

[0029] Furthermore, both the upper and lower flow channels employ a spiral structure.

[0030] In one possible implementation, the conductive filler is one or more of expanded graphite, flake graphite, carbon black, long carbon fiber, and short carbon fiber.

[0031] In one possible implementation, the polymer resin is one or more of PVDF, PP, PE, and PVC.

[0032] In one possible implementation, the conductive plastic raw material 8 contains 10% to 50% by volume of conductive filler and 20% to 90% by volume of polymer resin mixture.

[0033] In one possible implementation, such as Figure 6 As shown, it also includes a carbon fiber felt cutting mold, which includes an upper cutting mold 5 and a lower cutting mold 6. The bottom of the upper cutting mold is provided with a cutting tip, and the top of the upper cutting mold is correspondingly offset with a cutting tip.

[0034] Furthermore, the uncut carbon fiber felt 7 is placed in the lower cutting mold 6, which has sharp corners for cutting. The upper cutting mold 5 has sharp corners that are offset from the lower mold 6. After the upper and lower molds are closed, the distance between their inner surfaces is 1mm. Simultaneously, the sharp corners for cutting partially cut the carbon fiber felt. The internal space formed within the mold and the gaps inside the cut carbon fiber felt constitute the injection filling area for conductive plastic material. After the conductive plastic material is injected into the injection mold using injection molding equipment and shaped, a conductive bipolar plate with flow channels is formed.

[0035] In one possible implementation, such as Figure 7As shown, a method for fabricating a conductive bipolar plate with flow channels for a flow battery includes the following steps: like Figure 5 As shown, the cut and shaped carbon fiber felt is placed in the injection mold and matches the concave and convex structures in the mold. The upper and lower molds are then closed. The conductive plastic raw material of the formula is injected into the injection mold using injection molding equipment, and then held under pressure to set the shape.

[0036] Furthermore, the cut and shaped carbon fiber felt 1 is placed in the lower mold 4 with a concave-convex structure, and the concave-convex structure in the mold corresponds and cooperates with each other. The upper mold 3 with the concave-convex structure also has concave-convex structures that correspond and cooperate with the cut and shaped carbon fiber felt 1. After the upper and lower molds are closed, the distance between the inner surfaces of the two molds is 1mm. The resulting internal space and the internal voids of the compressed cut and shaped carbon fiber felt 1 are the injection filling area for conductive plastic raw materials. After the conductive plastic raw materials are injected into the injection mold by injection molding equipment and shaped, a conductive bipolar plate with flow channels is formed.

[0037] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A conductive bipolar plate with flow channels for a flow battery, characterized in that: The device includes a pre-cut carbon fiber felt, with symmetrical upper and lower channels at both ends. The outer surface of the pre-cut carbon fiber felt is covered with a conductive plastic material, which is a mixture of conductive filler and polymer resin. The pre-cut carbon fiber felt is formed by a die or cutting equipment, and its thickness is 4-8 mm. An intermediate felt with a thickness of 1 mm is located between the upper and lower channels. The channel depth is 1-2 mm and the width is 1-3 mm. Both the upper and lower channels have a spiral structure. In the conductive plastic material, the volume percentage of conductive filler is 10%-50%, and the volume percentage of polymer resin mixture is 20%-90%. The device also includes a carbon fiber felt cutting die, comprising an upper cutting die and a lower cutting die. The bottom of the upper cutting die has a cutting point, and the top of the upper cutting die has a corresponding offset cutting point.

2. The conductive bipolar plate with flow channels for a flow battery as described in claim 1, characterized in that: The conductive filler is one or more of expanded graphite, flake graphite, carbon black, long carbon fiber, and short carbon fiber.

3. The conductive bipolar plate with flow channels for a flow battery as described in claim 1, characterized in that: The polymer resin is one or more of PVDF, PP, PE, and PVC.

4. A method for fabricating a conductive bipolar plate with flow channels for a flow battery, characterized in that, Includes the following steps: The cut and shaped carbon fiber felt is placed in the injection mold and matches the concave and convex structures in the mold. The upper and lower molds are then closed. The conductive plastic raw material of the formula is injected into the injection mold using injection molding equipment, and then held under pressure to set the shape.

Images