A high-pressure and high-efficiency impregnation device and method for a new energy material graphite product

Abstract

This invention discloses a high-pressure, high-efficiency impregnation device and method for graphite products used in new energy materials, belonging to the field of graphite material impregnation and modification technology. The high-pressure, high-efficiency impregnation device for graphite products includes a shell, a magnetic rotor, a vacuum circulation system, and a pulse oscillator. A control panel is located on the top of the shell, and an excitation impregnation cylinder is horizontally installed inside the shell. Direct current can be supplied to the impregnation cylinder to generate Joule heating, or alternating current can be supplied to generate a rotating magnetic field, causing the magnetic rotor to rotate. A support frame mounted on the inner wall of the magnetic rotor is used to unidirectionally place graphite bipolar plates. The rear end of the excitation impregnation cylinder is connected to the vacuum circulation system to achieve gas-liquid replacement through vacuuming. A pulse oscillator and a replacement tank are connected in series in the vacuum circulation system. In the pulse oscillation vacuum pressure impregnation process, the pulse oscillator compresses the inert gas to generate mechanical vibration waves, which are coupled with vacuum pressure to improve the impregnating agent filling rate and penetration uniformity, achieving efficient densification modification of the bipolar plates.

Description

Technical Field

[0001] This invention belongs to the field of vacuum pressure impregnation and modification technology of pulse oscillation graphite materials. Specifically, it relates to a high-pressure and high-efficiency impregnation device and method for graphite products of new energy materials. Background Technology

[0002] As a core component of fuel cells and flow batteries, graphite bipolar plates directly determine the operating efficiency and lifespan of batteries due to their density, airtightness, mechanical properties, and conductivity. However, due to the presence of numerous micropores, blind pores, and closed pores in graphite materials, these pores can lead to increased brittleness and permeability of the bipolar plates, which can easily cause problems such as electrolyte leakage and gas cross-permeation, seriously affecting battery performance.

[0003] Currently, the densification modification of graphite bipolar plates mainly adopts the traditional vacuum pressure impregnation (VPI) process. Its core is to use static vacuum exhaust and pressure difference to draw preheated resin from the storage tank into the impregnation tank until the workpiece is completely submerged. Then, compressed inert gas is introduced into the tank to the set pressure and the pressure is maintained for tens of minutes to several hours, allowing the resin to fully penetrate under pressure to fill the pores.

[0004] However, in actual production, this process has obvious defects. For example, static high pressure can easily form a "liquid seal" at the pore inlet, which prevents the residual gas inside the pore from being completely discharged, resulting in problems such as insufficient filling of deep micropores and blind holes. At the same time, the impregnating agent has poor penetration uniformity under static pressure. For molded graphite bipolar plates with a thickness of 1.0 to 3.0 mm, the edges are often dense while the center is loose. Multiple impregnation-firing / curing processes are required to meet the performance requirements. The process cycle is long, the efficiency is low, and the production cost is high.

[0005] To address the aforementioned technical challenges, there is an urgent need for a graphite bipolar plate impregnation process that can improve the impregnation filling rate, uniformity, and penetration depth while shortening the process cycle. Summary of the Invention

[0006] The main objective of this invention is to provide a high-pressure, high-efficiency impregnation device and method for graphite products, a new energy material. The aim is to solve the problems of insufficient filling, poor uniformity, and long process cycle in the existing traditional vacuum pressure impregnation process for graphite bipolar plates, based on the existing process.

[0007] According to a first aspect of the invention: To achieve the above objectives, this invention discloses a high-pressure, high-efficiency impregnation device for graphite products, a new energy material, comprising: The housing has a control panel on top, and an excitation impregnation cylinder is horizontally installed inside the housing. A sealing cover is hinged to the open end of the excitation impregnation cylinder. A magnetic rotor is rotatably mounted at the axis of the excitation impregnation cylinder. A carrying frame is mounted on the inner wall of the magnetic rotor, and several graphite bipolar plates are arranged unidirectionally inside the carrying frame. The vacuum circulation system has its input end connected to the rear axis of the excitation impregnation cylinder, and its output end connected to the side of the excitation impregnation cylinder. The vacuum circulation system is equipped with a pulse oscillator and a displacement tank connected in series, and the displacement tank is filled with an impregnating agent.

[0008] Furthermore, the pulse oscillator includes: The shaking tank has a guide tube at its axis and an air guide hole on its side. A pulse coil piston, with a spiral coil installed inside, is slidably sleeved on the guide tube; The spring has its first end connected to the spiral coil and its last end connected to the magnetic block. The magnetic block is fixed to the bottom of the oscillating tank, and electrical contacts are arranged on the outside of the oscillating tank. The connecting contact is adapted to connect with the vortex coil to generate an induced magnetic field that repels the magnetic field of the magnetic block, and drives the pulse coil piston to reciprocate under the alternating action of the spring force.

[0009] Furthermore, the vacuum circulation system includes: The vacuum pump has its input end connected to the excitation impregnation cylinder via an air inlet pipe; The exhaust pipe is connected at its first end to the output end of the vacuum pump and at its last end to the discharge coil. The exhaust pipe is equipped with the pulse oscillator, the first solenoid valve, the displacement tank and the third solenoid valve arranged in series. The side of the displacement tank is connected to the excitation impregnation cylinder through the second solenoid valve.

[0010] Furthermore, the replacement tank includes a pressure tank, a gas inlet, a recovery port, and a vent. The pressure tank is provided with a vent at its front and rear ends, and the pressure tank is provided with a gas inlet and a recovery port symmetrically on its side. The pressure tank contains inert gas, and the gas supply port is connected to the gas station.

[0011] Furthermore, the excitation impregnation cylinder includes a cylinder shell, a drain pipe, a stator winding, and a spraying hole. The magnetic rotor is located at the axis of the cylinder shell. Several drain pipes are evenly arranged circumferentially on the inner side of the cylinder shell, and each drain pipe is connected to the discharge coil. The outer side of the drain pipe is provided with several spray holes leading into the cylindrical shell, and several stator windings are fixedly installed on the cylindrical shell. In this process, three-phase electricity is supplied to several of the stator windings to form a rotating magnetic field that drives the magnetic rotor to rotate.

[0012] Furthermore, the magnetic rotor includes: The rotor cylinder has a bearing at the center of its tail end, and the bearing is sleeved on the intake pipe; A number of permanent magnets are uniformly embedded on the outside of the rotor cylinder, and a number of permeation holes are arranged between two adjacent permanent magnets. A guide rail is welded inside the rotor cylinder. A shelf is slidably mounted inside the guide rail.

[0013] Furthermore, the rack includes a frame, a slot, a rotary joint, and a tail hole. The frame is cubic in shape and the tail hole is provided at the tail end. The tail hole is aligned with the bearing. The frame is provided with a rotary joint at its front end, which is adapted to be inserted into the center of the sealing cover and to support the rotation of the rotor cylinder.

[0014] Furthermore, the housing includes: The chassis has an internal isolation cover, and an excitation immersion cylinder is fixedly sleeved inside the isolation cover. An exhaust port is located at the bottom center of the isolation cover, and the exhaust port is provided with multiple sealing slots around its circumference. The sealing slots are used to install the discharge coil. The drain port is located on the outside of the isolation cover and is connected to the recovery port through the second solenoid valve.

[0015] According to a second aspect of the invention: This invention provides a high-pressure, high-efficiency impregnation method for graphite products, using the graphite bipolar plate impregnation integrated machine described above, and includes the following process: Molded graphite or composite graphite bipolar plates with a thickness of 1.0–3.0 mm, an open area ratio of 15%–25%, and a micropore size of 0.1–5 μm are selected and placed in the carrier. The excitation impregnation cylinder is filled with inert protective gas, and then DC current is passed into the stator winding to generate Joule heat. Finally, the plates are dried at 120°C for 2 hours, thereby removing adsorbed water on the surface of the plates and residual moisture in the pores, and reducing impregnation resistance. The vacuum pump is started to exhaust the vacuum, so that the cylinder shell is in a negative pressure state. At this time, the vacuum degree is ≤50Pa and maintained for 30 minutes to completely remove the air and residual gas in the micropores, blind holes and closed holes inside the inner plate of the excitation impregnation cylinder. Then, the third solenoid valve is opened to allow the impregnating agent in the pressure tank to enter the excitation impregnation cylinder through the discharge coil. The vacuum state of the excitation impregnation cylinder remains unchanged. A low-viscosity epoxy / phenolic modified impregnating agent with a temperature controlled at 50-60℃ is injected into the excitation impregnation cylinder, and three-phase AC power is passed into the stator winding to generate a rotating magnetic field, which in turn drives the magnetic rotor to rotate. Then, the impregnating agent is sprayed onto the surface of the immersed graphite bipolar plate through the spraying hole for 5-10 minutes. The vacuum pump operates continuously to introduce the inert protective gas from the excitation impregnation cylinder into the oscillating tank. The mechanical periodic pulse is generated by the alternating action of the magnetic force generated by the pulse coil piston and the elastic force of the spring. The impregnation is carried out in a step-by-step pressure increase + periodic pulse + cyclic pressure relief and exhaust mode. After the pulse impregnation is completed, the pressure in the impregnation tank is reduced to normal pressure within 5 minutes by slow depressurization. Then, the magnetic rotor rotates to generate centrifugal force to shake off the excess impregnating agent on the surface of the graphite bipolar plate, so as to avoid the impregnating agent inside the plate flowing back due to the sudden pressure drop. Finally, the second solenoid valve is opened to allow the impregnating agent to flow back into the replacement storage tank. A stepped heating pre-curing method is used to pre-cur the spin-dried graphite bipolar plate. The specific process is as follows: DC current is passed through the stator winding to generate Joule heat, the temperature is raised to 80℃ and held for 30 minutes, then the temperature is raised to 120℃ and held for 60 minutes, then the temperature is raised to 150℃ and held for 30 minutes to allow the impregnating agent to initially cure. Finally, the pre-cured graphite bipolar plate is heated to 180℃ in the cylinder and held for 60 minutes to allow the impregnating agent to completely cure and form a firm bond with the graphite matrix, achieving complete pore sealing. The performance of the post-cured graphite bipolar plates was tested, and the finished products that met the requirements were selected.

[0016] Furthermore, the specific parameters of the periodic pulse include a base pressure of 1.2 MPa, a pulse peak value of 1.5 MPa, a pulse valley value of 0.7 MPa, a peak-valley cycle every 2 seconds, a pulse waveform of triangular wave or square wave, and a total pulse pressure holding time of 90 minutes.

[0017] The beneficial effects of applying the technical solution of this invention include: Significantly improved filling effect: Through the dynamic action of pulsed oscillation pressure, the liquid sealing bottleneck of traditional static high-pressure impregnation is broken, so that residual air bubbles in the pores are completely broken and discharged. The impregnating agent can penetrate into deep micropores and blind pores of 0.1-5μm. The weight gain rate of one impregnation reaches 16%-20%, which is 30-50% higher than the traditional VPI process. The plate volume density is increased to 1.88-1.95g / cm³, and the porosity is reduced to ≤6%, which completely solves the problem of central porosity.

[0018] Significantly improved process efficiency: The pulse oscillation impregnation method reduces the total impregnation time (including pulse pressure holding) to only 90 minutes, replacing the traditional static pressure holding of 3-4 hours. Combined with the fact that a single impregnation can achieve the performance effect of 2-3 impregnations in the traditional method, the process cycle is shortened by 30-50%, significantly reducing production costs.

[0019] Stable product performance: Pulsed oscillation ensures uniform filling of the impregnating agent, with consistent density at the edge and center of the electrode plate, reducing permeability to ≤10%. -8 cm²·s -1 The airtightness meets the first-level standard for bipolar plates of fuel cells and flow batteries, while the mechanical properties (bending strength 45-55MPa) and electrical conductivity are effectively guaranteed without significant decline. Strong process compatibility: It is suitable for molded graphite and composite graphite bipolar plates with a diameter of 1.0 to 3.0 mm. The pulse parameters can be finely adjusted according to the specific specifications of the plate. There is no need to make large-scale modifications to the existing vacuum pressure impregnation equipment. It can be achieved simply by adding a pulse pressure control module, which is easy to promote in industrial applications. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a perspective view of the high-pressure, high-efficiency impregnation device for graphite products, a new energy material, disclosed in this invention. Figure 2 This is a three-dimensional view of the internal structure of the high-pressure, high-efficiency impregnation device for graphite products, a new energy material, disclosed in this invention. Figure 3 This is a perspective view of the vacuum circulation system disclosed in this invention; Figure 4 This is a perspective view of the magnetic rotor disclosed in this invention; Figure 5 This is a perspective view of the housing disclosed in this invention; Figure 6 This is a perspective view of the pulse oscillator disclosed in this invention; Figure 7 This is a perspective view of the pulse coil piston disclosed in this invention; Figure 8 This is a perspective view of the excitation impregnation cylinder disclosed in this invention; Figure 9 This is a perspective view of the replacement storage tank disclosed in this invention; Figure 10 This is a flowchart of the high-pressure, high-efficiency impregnation method for graphite products disclosed in this invention; The above figures include the following reference numerals: 1. Housing; 11. Chassis; 12. Exhaust port; 13. Sealing slot; 14. Drain outlet; 15. Isolation cover; 2. Sealing cover; 3. Magnetic rotor; 31. Rotor cylinder; 32. Bearing; 33. Permanent magnet; 34. Permeation hole; 35. Guide rail; 4. Excitation impregnation cylinder; 41. Cylinder shell; 42. Drain pipe; 43. Stator winding; 44. Spraying hole; 5. Vacuum circulation system; 51. Vacuum pump; 52. Inlet pipe; 53. Exhaust pipe; 54. First solenoid valve; 55. Discharge coil; 56. Second solenoid valve; 57. Third solenoid valve; 6. Shelf; 61. Shelf body; 62. Slot; 63. Rotary joint; 64. Tail hole; 7. Pulse oscillator; 71. Oscillating tank; 72. Guide tube; 73. Pulse coil piston; 74. Air guide hole; 75. Spring; 76. Electrical contact; 77. Spiral coil; 78. Magnetic block; 8. Replacement storage tank; 81. Pressure tank; 82. Air replenishment port; 83. Recovery port; 84. Vent; 9. Control panel. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in sequences other than those illustrated or described herein.

[0025] Furthermore, the terms “including” and “having” and any variations thereof are intended to cover non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, which is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0026] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., may be used here to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figure. It should be understood that spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device as described in the figure.

[0027] For example, if a device in the accompanying drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below". The device may also be positioned differently, rotated 90 degrees, or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0028] Please refer to this as well. Figures 1-9 This invention discloses a high-pressure, high-efficiency impregnation device for graphite products, a new energy material. It uses a pulsed oscillation vacuum pressure impregnation (Pulse-VPI) process to fill the micropores, blind holes, and closed pore structures in graphite bipolar plates. The main structure and working principle of the device disclosed in this invention will be explained below with specific embodiments.

[0029] In a specific embodiment of this invention, the high-pressure, high-efficiency impregnation device for graphite products, a new energy material, mainly includes a housing 1, a magnetic rotor 3, a vacuum circulation system 5, and a pulse oscillator 7. A control panel 9 is located on the top of the housing 1. The control panel 9 includes a function knob and a touchscreen. The touchscreen displays function commands, while the function knob is used to adjust parameters such as time, speed, and pressure. In this embodiment, an excitation impregnation cylinder 4 is horizontally installed inside the housing 1. A sealing cover 2 is hinged to the open end of the excitation impregnation cylinder 4. A rubber sealing ring is provided on the outer edge of the sealing cover 2. The sealing cover 2 can fix and seal the excitation impregnation cylinder 4 inside the housing 1. By passing DC current through the excitation impregnation cylinder 4 to generate Joule heating or by passing three-phase AC current through it to generate a rotating magnetic field, the magnetic rotor 3 is driven to rotate. The magnetic rotor 3 is rotatably positioned at the axis of the excitation impregnation cylinder 4. Simultaneously, a carrier 6 is mounted on the inner wall of the magnetic rotor 3. Several graphite bipolar plates are arranged unidirectionally within the carrier 6 to allow the impregnating agent to penetrate through a comprehensive spraying method. On the other hand, the rear axis of the excitation impregnation cylinder 4 is connected to the input end of the vacuum circulation system 5, and the output end of the vacuum circulation system 5 is connected to the side of the excitation impregnation cylinder 4. The vacuum circulation system 5 achieves gas-liquid replacement (inert gas-impregnating agent replacement) in the excitation impregnation cylinder 4 by evacuation, wherein the impregnating agent is loaded into the replacement storage tank 8. A pulse oscillator 7 and the replacement storage tank 8 are connected in series on the vacuum circulation system 5. The pulse oscillator 7 periodically squeezes the inert gas to generate mechanical vibration waves. Then, through the coupling effect of pulse oscillation and vacuum pressure, the pore liquid seal is broken, the gas is discharged, and the filling rate and penetration uniformity of the impregnating agent are improved, thereby achieving efficient densification modification of the graphite bipolar plate.

[0030] In some embodiments, such as Figure 6 and Figure 7 The pulse oscillator 7 includes an oscillating tank 71, a pulse coil piston 73, and a spring 75. The oscillating tank 71 is a pressure-resistant tank wrapped with carbon fiber. A guide tube 72 is provided at the axis of the oscillating tank 71. A vent hole 74 is opened on the side of the guide tube 72. The oscillating tank 71 is connected to the vacuum circulation system 5 through the vent hole 74 and the guide tube 72. A pulse coil piston 73 is slidably mounted on the guide tube 72, and a spiral coil 77 is installed inside the pulse coil piston 73. The spiral coil 77 is connected to the first end of the spring 75. When the spiral coil 77 is energized, it can instantly generate a strong electromagnetic field. On the other hand, the spring 75 mounted on the guide tube 72 has one end connected to the pulse coil piston 73 and the other end connected to the magnetic block 78. The magnetic block 78 is fixed to the bottom of the oscillating tank 71. An electrical contact 76 is arranged on the outside of the oscillating tank 71. The electrical contact 76 is used to connect to an external power source. The electrical contact 76 is suitable for connecting to the spiral coil 77 to generate an induced magnetic field. The induced magnetic field and the inherent magnetic field of the magnetic block 78 generate a repulsive force. Thus, under the alternating action of the spring force of the spring 75, the pulse coil piston 73 is driven to move back and forth.

[0031] In some embodiments, such as Figure 3 The vacuum circulation system 5 includes a vacuum pump 51, an exhaust pipe 53, and a discharge coil 55. The input end of the vacuum pump 51 is connected to the excitation impregnation cylinder 4 via an air inlet pipe 52, while the output end of the vacuum pump 51 is connected to the beginning end of the exhaust pipe 53. In this embodiment, the tail end of the exhaust pipe 53 is connected to the discharge coil 55. Structurally, a pulse oscillator 7, a first solenoid valve 54, a displacement tank 8, and a third solenoid valve 57 are arranged in series on the exhaust pipe 53. The side of the displacement tank 8 is connected to the excitation impregnation cylinder 4 via a second solenoid valve 56. When the vacuum circulation system 5 is running, the vacuum pump 51 is started, putting the excitation impregnation cylinder 4 under negative pressure. The first solenoid valve 54 and the third solenoid valve 57 are opened, and the impregnating agent in the displacement tank 8 is drawn into the excitation impregnation cylinder 4, thereby covering the surface of the graphite bipolar plate with the impregnating agent.

[0032] In this embodiment, as Figure 9 The replacement storage tank 8 includes a pressure tank 81, a gas inlet 82, a recovery port 83, and a vent 84. The pressure tank 81 is provided with a vent 84 at both the front and rear ends. The pressure tank 81 is symmetrically provided with a gas inlet 82 and a recovery port 83 on its side. It should be noted that the pressure tank 81 is filled with inert gas, and the gas inlet 82 is connected to a gas station. Nitrogen can be added to or released from the pressure tank 81 through the gas station to regulate the internal gas pressure.

[0033] In this embodiment, as Figure 5 The housing 1 includes a chassis 11, an exhaust port 12, and a drain port 14. An isolation cover 15 is installed inside the chassis 11 to prevent impregnating agent leakage. An excitation impregnation cylinder 4 is fixedly fitted inside the isolation cover 15. An exhaust port 12 is located at the center of the bottom of the isolation cover 15. An air inlet pipe 52 can be inserted into the exhaust port 12, and using the air inlet pipe 52 as a support shaft, when the excitation impregnation cylinder 4 generates a rotating magnetic field, the magnetic rotor 3 can rotate around the support shaft. Furthermore, multiple sealing slots 13 are arranged circumferentially around the exhaust port 12 for installing a discharge coil 55. This allows the impregnating agent to be sprayed simultaneously through the excitation impregnation cylinder 4, ensuring uniform adhesion of the impregnating agent to the surface of the graphite bipolar plate. The drain port 14 is located on the outside of the isolation cover 15 and is connected to a recovery port 83 via a second solenoid valve 56 to recover dripped impregnating agent.

[0034] In this embodiment, as Figure 8The excitation impregnation cylinder 4 includes a cylinder shell 41, drain pipes 42, stator windings 43, and spray holes 44. The magnetic rotor 3 is located at the axis of the cylinder shell 41. Several drain pipes 42 are evenly arranged circumferentially on the inner side of the cylinder shell 41, and each drain pipe 42 is connected to a discharge coil 55. Several spray holes 44 are arranged on the outer side of the drain pipes 42 into the cylinder shell 41. The stator windings 43 are fixedly installed on the cylinder shell 41. Three-phase electricity is passed through the stator windings 43 to form a rotating magnetic field that drives the magnetic rotor 3 to rotate. Inside the magnetic rotor 3, a carrier frame 6 is installed, in which multiple graphite bipolar plates are arranged in a unidirectional manner.

[0035] In some embodiments, such as Figure 4 The magnetic rotor 3 includes a rotor cylinder 31 and permanent magnets 33. A bearing 32 is located at the center of the tail of the rotor cylinder 31, and the bearing 32 is fitted onto the air inlet pipe 52, allowing the rotor cylinder 31 to rotate freely. Several permanent magnets 33 are evenly embedded on the outside of the rotor cylinder 31, and several permeation holes 34 are arranged between adjacent permanent magnets 33 to allow impregnating agent to enter the rotor cylinder 31. A guide rail 35 is welded inside the rotor cylinder 31, and a shelf 6 is slidably engaged within the guide rail 35. Specifically, the shelf 6 includes a frame body 61, a slot 62, a rotary joint 63, and a tail hole 64. The frame body 61 has a cubic hollow structure, and a tail hole 64 is located at the tail of the frame body 61. The tail hole 64 is aligned with the bearing 32 and can be fitted onto the air inlet pipe 52. A rotary joint 63 is located at the head of the frame body 61, and the rotary joint 63 is suitable for insertion into the center of the sealing cap 2 to support the rotation of the rotor cylinder 31.

[0036] Based on the same inventive concept, this invention also discloses a high-pressure, high-efficiency impregnation method for graphite products, using the high-pressure, high-efficiency impregnation device for new energy material graphite products as described above, including the following steps: Step 1: Selection and loading of electrode plates. Select molded graphite or composite graphite bipolar plates with a thickness of 1.0–3.0 mm, an open area ratio of 15%–25%, and a micropore size of 0.1–5 μm as the workpieces to be impregnated. Arrange them neatly in the carrier 6, ensuring that the electrode plate surface is free of damage and oil stains. After the carrier 6 is placed in the excitation impregnation cylinder 4, close the sealing cover 2 of the excitation impregnation cylinder 4 to ensure good sealing inside the cylinder. Step 2: Inert gas protection and drying. Fill the excitation impregnation cylinder 4 with inert protective gas (nitrogen gas with a purity ≥99.99% is used in this embodiment) to purge the air inside the cylinder and prevent oxidation of the graphite bipolar plates during subsequent drying and impregnation processes. Subsequently, direct current is applied to the stator winding 43, and the Joule heat generated by the stator winding 43 is used to heat the inside of the excitation impregnation cylinder 4. The heating temperature is controlled and stabilized at 120℃, and this temperature is maintained for drying for 2 hours. Drying removes the moisture adsorbed on the surface of the electrode plate and the residual moisture in the internal pores, effectively reducing the impregnation resistance in the subsequent impregnation process and ensuring that the impregnating agent can smoothly penetrate into the micropores inside the electrode plate. Step 3: High vacuum degassing treatment. After drying, the vacuum pump 51 in the vacuum system 5 is started to degas the vacuum, so that the cylinder shell 41 of the excitation impregnation cylinder 4 is in a negative pressure state. The vacuum is continuously pumped until the vacuum degree inside the cylinder is less than 50Pa, and then the vacuum degree is maintained for 30 minutes. Through the high vacuum environment, the residual air and other gases in the micropores, blind holes and closed holes inside the graphite bipolar plate are completely removed, avoiding the formation of bubbles in the pores, which would hinder the penetration of the impregnating agent and lay the foundation for the subsequent impregnation process. Step 4: Impregnating Agent Injection. Maintaining the vacuum state within the excitation impregnation cylinder 4, open the third solenoid valve 57 to slowly inject the pre-stored low-viscosity epoxy / phenolic modified impregnating agent from the pressure tank 81 into the excitation impregnation cylinder 4 through the discharge coil 55. During injection, control the impregnating agent temperature to be maintained between 50 and 60°C. At this temperature, the impregnating agent viscosity is lowest and its flowability is optimal, effectively improving impregnation efficiency. The injection amount should be sufficient to completely submerge all the graphite bipolar plates on the carrier 6. Step 5: Magnetic Stirring and Spray Impregnation. After the impregnating agent injection is complete, three-phase AC power is supplied to the stator winding 43. The stator winding 43 generates a rotating magnetic field, which drives the magnetic rotor 3 within the excitation impregnation cylinder 4 to rotate. During the rotation of the magnetic rotor 3, the impregnating agent is stirred to ensure uniform distribution. Simultaneously, under the combined action of centrifugal force and negative pressure within the cylinder, the impregnating agent is evenly sprayed onto the surface of the graphite bipolar plate through the spray holes 44 on the inner wall of the excitation impregnation cylinder 4. This spraying process lasts 5–10 minutes, ensuring the plate surface is completely covered by the impregnating agent, preparing for subsequent deep impregnation. Step 6: Pulse oscillation and stepped pressure impregnation, while maintaining continuous operation of the vacuum pump 51 to continuously introduce the inert protective gas from the excitation impregnation cylinder 4 into the oscillation tank 71 of the pulse oscillation system.Inside the oscillating tank 71, the pulse coil piston 73 generates mechanical periodic pulses under the alternating action of magnetic force and spring force 5. These pulses are transmitted to the excitation impregnation cylinder 4, compressing the inert gas to create an oscillation effect on the impregnating agent and graphite bipolar plate, thereby promoting the penetration of the impregnating agent into the micropores inside the plate. Based on this, a composite impregnation mode of "step-by-step pressurization + periodic pulse + cyclic pressure relief and exhaust" is adopted. During the step-by-step pressurization process, the pressure inside the cylinder is gradually increased (the pressurization rate is 0.1 MPa / min, and the final pressure is controlled at 0.3 to 0.5 MPa). Combined with the oscillation effect of the periodic pulse and the cyclic pressure relief and exhaust (the pressure is reduced to 0.1 MPa every 10 minutes, and the pressure is increased again after 30 seconds of exhaust), the graphite bipolar plate is deeply impregnated, ensuring that the impregnating agent completely fills all the pores inside the plate. Step 7: Slow depressurization and centrifugal drying. After pulse impregnation, a slow depressurization method is used to control the depressurization rate, reducing the pressure in the excitation impregnation cylinder 4 to atmospheric pressure within 5 minutes. This prevents the impregnating agent in the pores inside the electrode plate from being sucked out due to a sudden pressure drop. After depressurization, the magnetic rotor 3 is restarted to rotate. The centrifugal force generated by the rotation is used to dry the excess impregnating agent adhering to the surface of the graphite bipolar plate, reducing impregnating agent waste and preventing defects such as sagging and glue accumulation on the electrode plate surface during subsequent curing. After drying, the second solenoid valve 56 is opened, allowing the remaining impregnating agent in the excitation impregnation cylinder 4 to flow back into the replacement storage tank 8 through the pipeline for subsequent recycling and reuse. Step 8: Step-by-step pre-curing. The spin-dried graphite bipolar plate is left in the excitation impregnation cylinder 4 and pre-cured using a step-by-step heating method. The specific process parameters are as follows: DC current is passed through the stator winding 43 to generate Joule heat. First, the temperature inside the cylinder is raised to 80°C and held for 30 minutes to allow the impregnating agent to initially set. Then, the temperature is raised to 120°C and held for 60 minutes to promote the initial bonding between the impregnating agent and the graphite matrix. Then, the temperature is raised to 150°C and held for 30 minutes to allow the impregnating agent to complete the initial curing and form a preliminary cured layer, thus avoiding the loss of impregnating agent during the subsequent complete curing process. Step 9: High-temperature complete curing. After pre-curing, continue heating through the stator winding 43 to raise the temperature inside the excitation impregnation cylinder 4 to 180℃ and maintain this temperature for 60 minutes to allow the impregnating agent to completely cure. The cured impregnating agent forms a strong chemical and physical bond with the graphite bipolar plate substrate, completely sealing all pores inside the plate and improving the density, corrosion resistance, and conductivity of the graphite bipolar plate. Step 10: Performance testing and finished product screening.After complete curing, turn off the heating and all power systems. After the temperature inside the excitation impregnation cylinder 4 drops to room temperature, open the sealing cover 2 and take out the graphite bipolar plate from the carrier 6. Perform performance testing on the removed graphite bipolar plate. The test items include porosity, volume resistivity, corrosion resistance and mechanical strength. Select finished products that meet the preset standards (porosity ≤0.5%, volume resistivity ≤10μΩ·m, acid and alkali corrosion resistance meets the standard, compressive strength ≥20MPa). Unqualified products can be impregnated again.

[0037] In this embodiment, the specific parameters of the mechanical cycle pulse include a base pressure of 1.2 MPa, a pulse peak value of 1.5 MPa, a pulse valley value of 0.7 MPa, and the pulse completes a peak-valley cycle every 2 seconds. The pulse waveform preferably adopts a triangular wave, which has a smooth pressure transition and can avoid damage to the microstructure of the graphite bipolar plate caused by instantaneous pressure shock. The total pulse pressure holding time is 90 minutes.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 high-pressure, high-efficiency impregnation device for graphite products, a new energy material, characterized in that, include: The housing (1) has a control panel (9) on top. An excitation impregnation cylinder (4) is horizontally installed inside the housing (1). A sealing cover (2) is hinged to the open end of the excitation impregnation cylinder (4). A magnetic rotor (3) is rotatably mounted on the axis of the excitation impregnation cylinder (4). A carrying rack (6) is mounted on the inner wall of the magnetic rotor (3). Several graphite bipolar plates are arranged unidirectionally inside the carrying rack (6). The vacuum circulation system (5) has its input end connected to the rear axis of the excitation impregnation cylinder (4), and its output end connected to the side of the excitation impregnation cylinder (4). The vacuum circulation system (5) is equipped with a pulse oscillator (7) and a displacement tank (8) connected in series, and the displacement tank (8) is filled with an impregnating agent.

2. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 1, characterized in that, The pulse oscillator (7) includes: The shaking tank (71) has a guide tube (72) at its axis, and the side of the guide tube (72) has an air guide hole (74). A pulse coil piston (73) has a spiral coil (77) installed inside it, and the pulse coil piston (73) is slidably sleeved on the guide tube (72); The spring (75) is connected at its first end to the spiral coil (77) and at its last end to the magnetic block (78). The magnetic block (78) is fixed at the bottom of the oscillating tank (71). Electrical contacts (76) are arranged on the outside of the oscillating tank (71). The connecting contact (76) is adapted to be connected to the vortex coil (77) to generate an induced magnetic field and repel the magnetic field of the magnetic block (78), and drive the pulse coil piston (73) to reciprocate under the alternating action of the spring force (75).

3. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 2, characterized in that, The vacuum circulation system (5) includes: The vacuum pump (51) is connected to the excitation impregnation cylinder (4) via an air inlet pipe (52) at its input end; The exhaust pipe (53) is connected at its first end to the output end of the vacuum pump (51) and at its last end to the discharge coil (55); The exhaust pipe (53) is connected in series with the pulse oscillator (7), the first solenoid valve (54), the replacement tank (8) and the third solenoid valve (57). The side of the replacement tank (8) is connected to the excitation impregnation cylinder (4) through the second solenoid valve (56).

4. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 1, characterized in that, The replacement storage tank (8) includes a pressure tank (81), a gas inlet (82), a recovery port (83), and a vent (84). The pressure tank (81) has a vent (84) at its front and rear ends, and the pressure tank (81) has a gas inlet (82) and a recovery port (83) symmetrically arranged on its side. The pressure tank (81) contains inert gas, and the gas supply port (82) is connected to the gas station.

5. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 4, characterized in that, The excitation impregnation cylinder (4) includes a cylinder shell (41), a drain pipe (42), a stator winding (43), and a spray hole (44). The magnetic rotor (3) is located at the axis of the cylinder shell (41). Several drain pipes (42) are evenly arranged circumferentially on the inner side of the cylinder shell (41), and each drain pipe (42) is connected to the discharge coil (55). The outer side of the drain pipe (42) is provided with a number of spray holes (44) extending into the cylindrical shell (41), and a number of stator windings (43) are fixedly installed on the cylindrical shell (41). Among them, a number of the stator windings (43) are supplied with three-phase electricity to form a rotating magnetic field that drives the magnetic rotor (3) to rotate.

6. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 5, characterized in that, The magnetic rotor (3) includes: The rotor cylinder (31) has a bearing (32) at the center of its tail, and the bearing (32) is sleeved on the air intake pipe (52); A number of permanent magnets (33) are uniformly embedded on the outside of the rotor cylinder (31), and a number of permeation holes (34) are arranged between two adjacent permanent magnets (33). A guide rail (35) is welded inside the rotor cylinder (31). The guide rail (35) is slidably provided with a carrier (6).

7. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 6, characterized in that, The rack (6) includes a frame (61), a slot (62), a rotary joint (63) and a tail hole (64). The frame (61) is cubic in shape and the tail hole (64) is provided at the tail end. The tail hole (64) is aligned with the bearing (32). The frame (61) is provided with a rotary joint (63) at its front end. The rotary joint (63) is adapted to be inserted into the center of the sealing cover (2) and to support the rotation of the rotor cylinder (31).

8. The high-pressure, high-efficiency impregnation device for graphite products as described in claim 7, characterized in that, The housing (1) includes: The chassis (11) has an internal isolation cover (15), and an excitation impregnation cylinder (4) is fixedly sleeved inside the isolation cover (15). An exhaust port (12) is located at the bottom center of the isolation cover (15). The exhaust port (12) is provided with a plurality of sealing slots (13) around its circumference. The sealing slots (13) are used to install the discharge coil (55). The drain port (14) is located on the outside of the isolation cover (15) and is connected to the recovery port (83) through the second solenoid valve (56).

9. A high-pressure, high-efficiency impregnation method for graphite products, using the graphite bipolar plate impregnation integrated machine as described in claim 8, characterized in that... The process includes the following: Select a molded graphite or composite graphite bipolar plate with a thickness of 1.0 to 3.0 mm, an open area ratio of 15% to 25%, and a micropore size of 0.1 to 5 μm. Place it in the carrier (6). Fill the excitation impregnation cylinder (4) with inert protective gas. Then, pass DC current into the stator winding (43) to generate Joule heat. Finally, dry it at 120°C for 2 hours. The vacuum pump (51) is started to exhaust the vacuum, so that the shell (41) is in a negative pressure state. At this time, the vacuum degree is ≤50Pa and maintained for 30 minutes. Then, the third solenoid valve (57) is opened, so that the impregnating agent in the pressure tank (81) enters the excitation impregnation cylinder (4) through the discharge coil (55). The excitation impregnation cylinder (4) remains in a vacuum state. A low-viscosity epoxy / phenolic modified impregnating agent with a temperature controlled at 50-60℃ is injected into the excitation impregnation cylinder (4), and three-phase AC power is passed into the stator winding (43) to generate a rotating magnetic field, which in turn drives the magnetic rotor (3) to rotate. Then, the impregnating agent is sprayed onto the surface of the immersed graphite bipolar plate through the spraying hole (44) for 5-10 minutes. The vacuum pump (51) operates continuously to introduce the inert protective gas of the excitation impregnation cylinder (4) into the oscillating tank (71). The mechanical periodic pulse is generated by the alternating action of the magnetic force generated by the pulse coil piston (73) and the elastic force of the spring (5). The impregnation is carried out in the mode of step pressure increase + periodic pulse + circulating pressure relief and exhaust. After the pulse impregnation is completed, the pressure in the impregnation tank is reduced to normal pressure within 5 minutes by slow depressurization. Then the magnetic rotor (3) rotates to generate centrifugal force to remove excess impregnating agent from the surface of the graphite bipolar plate. Finally, the second solenoid valve (56) is opened so that the impregnating agent flows back to the replacement storage tank (8). The graphite bipolar plate after spin-drying is pre-cured by a stepped heating pre-curing method. The specific process is as follows: DC current is passed through the stator winding (43) to generate Joule heat, the temperature is raised to 80℃ and kept for 30 minutes, then the temperature is raised to 120℃ and kept for 60 minutes, then the temperature is raised to 150℃ and kept for 30 minutes to allow the impregnating agent to be initially cured. Finally, the pre-cured graphite bipolar plate is heated to 180℃ in the cylinder shell (41) and kept for 60 minutes to allow the impregnating agent to be completely cured and form a firm bond with the graphite matrix, thereby achieving complete pore sealing. The performance of the post-cured graphite bipolar plates was tested, and the finished products that met the requirements were selected.

10. The high-pressure, high-efficiency impregnation method for graphite products as described in claim 9, characterized in that, The specific parameters of the periodic pulse include a base pressure of 1.2 MPa, a pulse peak value of 1.5 MPa, a pulse valley value of 0.7 MPa, a peak-valley cycle every 2 seconds, a pulse waveform of triangular wave or square wave, and a total pulse pressure holding time of 90 minutes.

Images