A method for manufacturing a dry mesophase pitch-based carbon paper

Abstract

This invention provides a dry-process method for manufacturing mesophase pitch-based carbon paper, including melting and stirring raw pitch, spinning to form continuous long mesophase pitch fibers, and then forming the final carbon paper through airflow-assisted drawing, rolling, pre-oxidation, and carbonization. This invention is a low-cost, completely liquid-free, environmentally friendly, and quality-controlled carbon paper production method composed of continuous long fibers. By using an auxiliary airflow to draw the continuous fibers after demolding, this invention forms a disordered mesophase pitch fiber layup on a mesh belt, which can uniformly form a three-dimensional cross-linked structure. This ensures that the three-dimensional cross-linked mesophase pitch fiber layup is maintained evenly after subsequent rolling and pre-oxidation heat treatment. After carbonization, the resulting carbon paper has a more uniform overall texture, stable quality, and better tensile strength, thermal conductivity, and electrical conductivity.

Description

Technical Field

[0001] This invention relates to the field of fuel cell gas diffusion layer technology, and more particularly to a method for manufacturing dry mesophase pitch-based carbon paper. Background Technology

[0002] A fuel cell is a non-combustion electrochemical energy conversion device. It typically uses fuels such as hydrogen and methanol, along with oxidants such as oxygen, to continuously convert chemical energy into electrical energy through a redox reaction. It is an electrochemical power generation device that does not require a Carnot cycle. Therefore, fuel cells can achieve efficiencies exceeding 90%, far surpassing those of conventional internal combustion engines.

[0003] Fuel cells use renewable energy sources such as hydrogen and methanol, rather than non-renewable resources like fossil fuels. This frees humanity from the constraints of geological conditions on energy availability. When fuel cells use pure hydrogen as fuel, the only chemical reaction product is water, fundamentally eliminating emissions of air pollutants such as CO, NOx, SOx, and particulate matter.

[0004] Fuel cells combine the characteristics of both batteries and heat engines, featuring high energy conversion efficiency, zero environmental pollutant emissions, rapid low-temperature start-up, and low vibration and noise levels. During energy conversion, they produce virtually no nitrogen and sulfur oxides that pollute the environment, making fuel cells considered an environmentally friendly energy conversion device. Due to these advantages, fuel cell technology is considered one of the new environmentally friendly and efficient power generation technologies of the 21st century.

[0005] The electrode of a proton exchange membrane fuel cell consists of a porous diffusion layer, a catalyst layer, and a proton exchange membrane. Fuel gas is distributed and wetted through the anode diffusion layer before reaching the catalyst layer, where an electrode reaction occurs under the action of the catalyst. The gas diffusion layer in the fuel cell not only supports the catalyst layer, collects current, and stabilizes the electrode structure, but also plays a crucial role in conducting and distributing gas and removing reaction product water.

[0006] Carbon fiber paper (carbon paper) is a widely used gas diffusion layer material in proton exchange membrane fuel cell electrodes. It not only possesses a uniform porous thin-layer structure, but also exhibits excellent electrical conductivity, chemical stability, and thermal stability due to the use of graphitized carbon fibers as its main raw material. High-performance gas diffusion layer materials are beneficial for improving the overall performance of the electrode.

[0007] Current fuel cell gas diffusion layers use PAN fibers, which are then carbonized and graphitized. Commercially sourced or self-made PAN-based carbon fibers are mechanically shortened and processed using traditional papermaking techniques. This process makes it difficult to produce low-cost, large-scale, highly stable, and highly conductive carbon paper. Furthermore, the current wet-process preparation requires water, various organic solutions and solvents with different properties, leading to environmental pollution during use and recycling. The papermaking process is also uneven, and the binders introduced to improve the tensile strength of the carbon paper cause a decrease in its electrical and thermal conductivity.

[0008] In the process of producing carbon paper using PAN-based carbon fiber as raw material, in order to obtain short-cut carbon fibers with stable surface properties, it is necessary to thoroughly clean the various surface functional agents applied during the production of PAN-based carbon fiber. This process also requires the consumption of water, organic solvents, etc.

[0009] Therefore, this application proposes a method for manufacturing dry mesophase pitch-based carbon paper. Summary of the Invention

[0010] This invention provides a method for manufacturing dry mesophase pitch-based carbon paper, which will solve the technical problems of pollution and uneven papermaking caused by the existing wet process for preparing short-cut fibers.

[0011] The technical solution provided by this invention is as follows:

[0012] A method for manufacturing dry-process mesophase pitch-based carbon paper includes the following steps:

[0013] S10. Melt the mesophase asphalt and stir it evenly;

[0014] S20. Molten mesophase pitch is spun into continuous long mesophase pitch fibers using a spinning machine.

[0015] S30. After demolding, the continuous long mesophase pitch fiber filaments are stretched, wound and laid on a temperature-adjustable and moving mesh belt by auxiliary airflow to form a continuous interlocking three-dimensional mesophase pitch fiber layup.

[0016] S40. The mesophase pitch fiber is rolled by a temperature-adjustable roller to form a fully overlapping three-dimensional mesophase pitch fiber layup.

[0017] S50. The mesophase pitch fiber layup is subjected to pre-oxidation heat treatment under a protective atmosphere to obtain a uniformly cross-linked and overlapping three-dimensional mesophase pitch fiber layup.

[0018] S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace in an oxygen-free environment to form carbon paper.

[0019] Mesophase pitch is spun into continuous long mesophase pitch fibers using a spinning machine. An auxiliary airflow is placed between the spinning die and the mesh belt. Before the continuous long mesophase pitch fibers fall onto the mesh belt, the airflow further stretches the fibers, causing them to intertwine. Simultaneously, the auxiliary airflow causes the intertwined fibers to lay irregularly on the mesh belt, forming a loose, continuous, three-dimensional mesophase pitch fiber layup. Mesophase pitch itself is inherently unspinnable and cannot be stretched to a suitable diameter using external equipment. However, this invention melts and spins molten mesophase pitch into continuous fibers using a spinning machine, and then further stretches these fibers using an auxiliary airflow. Throughout the stretching process, the mesophase pitch fibers remain continuous long fibers. Compared to chopped mesophase pitch fibers, which have the following disadvantages...

[0020] 1. Short-cut fiber raw materials have many sources, and the quality of adsorbents on the surface of the raw materials is unstable. At the same time, during the papermaking process, short-cut fibers require the introduction of binders and other liquids, such as suspensions and pulps, which makes quality control difficult and also causes pollution, reduced electrical and thermal conductivity, uneven density distribution, and increased costs. In contrast, this invention only uses mesophase pitch, which does not require the introduction of water or any liquids during the preparation of carbon paper. This makes the entire carbon paper preparation process more environmentally friendly and does not generate pollutants.

[0021] 2. Short-cut carbon fibers have a smooth surface and stable performance, making it difficult to form an overlapping structure, which reduces the tensile strength of carbon paper and lowers its electrical conductivity. Insufficient overlap also leads to poor thermal conductivity. In contrast, the continuous long mesophase pitch fiber filaments in this invention form a three-dimensional structure by winding and overlapping during the drawing process. Not only do the single continuous long mesophase pitch fiber filaments wind and overlap with each other, but the multiple filaments coming out of the spinning die also wind and overlap with each other when they are laid up on the mesh belt, thus resulting in better tensile strength of the layup after roll forming.

[0022] Preferably, the temperature of the auxiliary airflow in step S30 is 0-90°C, and the auxiliary airflow is divided into stretching airflow and turbulent airflow;

[0023] The stretching airflow is located between the spinning die and the mesh belt. The stretching airflow acts on the continuous mesophase pitch fiber filaments after they leave the die, causing the continuous mesophase pitch fiber filaments to stretch and wrap.

[0024] The turbulent flow is positioned near the surface of the mesh belt, and the turbulent flow acts on the stretched mesophase pitch fiber filaments, causing the mesophase pitch fiber filaments to be further entangled and laid out disorderly on the mesh belt.

[0025] The auxiliary airflow in this technical solution is divided into a stable stretching airflow section and a turbulent flow section. The stretching airflow is positioned between the die and the mesh belt, continuously blowing onto the continuous long mesophase pitch fibers, causing them to stretch and entangle. The turbulent flow further entangles the falling, continuously entangled long mesophase pitch fibers, allowing them to be laid along the surface of the mesh belt, forming a disordered three-dimensional layup of mesophase pitch fibers. This technical solution does not limit the specific configuration of the stretching and turbulent airflows, as long as the stretching airflow can stretch the mesophase pitch fibers; similarly, the specific configuration of the turbulent flow is not limited, as long as the turbulent flow allows the mesophase pitch fibers to be evenly laid on the mesh belt.

[0026] Preferably, in step S30, the speed of the mesh belt can be adjusted to adjust the density and thickness of the mesophase asphalt fiber layup, and the adjustment range of the mesh belt speed is 1-55m / min;

[0027] The temperature adjustment range of the mesh belt in step S30 is 90-490℃;

[0028] In step S40, the temperature range of the pressure roller is 140-490℃.

[0029] Preferably, the auxiliary airflow in step S30 is a continuous airflow, which is drawn by the airflow acting on the mesophase pitch fiber and flows to the surface of the mesh belt and diffuses to the surroundings to form turbulence.

[0030] In this technical solution, the auxiliary airflow is a continuous airflow. The stretching airflow acting on the mesophase pitch fiber filaments flows towards the surface of the mesh belt. The airflow entering the mesh belt surface diffuses around the mesh belt surface to form turbulence. The turbulence can cause the mesophase pitch fiber filaments falling onto the mesh belt surface to further wrap around the airflow direction and fall onto the mesh belt. At this time, the mesophase pitch fiber filaments are continuous and more disordered, which can form disordered three-dimensional cross-linked mesophase pitch fiber filaments. After roll forming and heat treatment, relatively good three-dimensional cross-linked mesophase pitch fiber filaments can be obtained.

[0031] Preferably, step S41 is included between step S40 and step S50. Step S41 is a shaping step. If the rolled layer does not reach the preset thickness and density, the speed of the conveyor belt needs to be reduced; if the rolled layer exceeds the preset thickness and density, the speed of the conveyor belt needs to be increased.

[0032] Preferably, the bulk density of the carbon paper in step S60 is 0.45-0.90 g / cm³. 3 .

[0033] Preferably, the tensile strength of the carbon paper in step S60 is 33-176 N / cm.

[0034] Preferably, the porosity of the carbon paper in step S60 is 65-95%.

[0035] Preferably, the thermal conductivity of the carbon paper prepared in step S60 at room temperature is: ≥3.5 W / (m·K) in the vertical direction and ≥55 W / (m·K) in the parallel direction; the resistivity (surface resistance) of the prepared carbon paper is <3.2 mΩ·cm.

[0036] Preferably, in step S20, the mesophase pitch fiber is prepared by spinning, with a spinning temperature of 260℃~420℃, a spinning speed of 0.3~80mm / s, and a distance of 30~90cm between the mesh belt and the spinneret.

[0037] Preferably, in step S50, the mesophase pitch fibers are heated to 240–370°C at a rate of 15°C / min;

[0038] The carbonization temperature in step S60 is 1100-3500℃.

[0039] Compared with the prior art, the method for manufacturing dry mesophase pitch-based carbon paper provided by the present invention has the following beneficial effects:

[0040] 1. This invention uses an auxiliary airflow to stretch continuous long mesophase pitch fiber filaments after demolding. The stretching airflow can also cause the continuous mesophase pitch fiber filaments to disperse irregularly, so that the mesophase pitch fiber filaments can be irregularly wrapped during the stretching process. After stretching, the disordered mesophase pitch fiber is laid on the mesh belt and can uniformly form a three-dimensional cross-linked structure. This allows for the formation of a uniform three-dimensional cross-linked mesophase pitch fiber layup after subsequent rolling and heat treatment. After carbonization, a uniform carbon paper is formed, and the formed carbon paper has better thermal conductivity and electrical conductivity.

[0041] 2. If the temperature of the mesophase pitch fiber filaments after demolding is too high or too low, which is not conducive to stretching, the temperature of the auxiliary airflow can be adjusted to cool or heat the mesophase pitch fiber filaments after demolding, so as to maintain the mesophase pitch fiber filaments within a suitable glass transition temperature range and keep them able to be stretched.

[0042] 3. In this invention, only mesophase pitch is used as the matrix material. No liquid is involved in the entire process of carbon paper preparation. It is environmentally friendly, has no secondary pollution, is low in cost, and has a simple and reliable process. Moreover, since no other liquid is introduced during the preparation of pure mesophase pitch, the quality is more controllable.

[0043] 4. In the preparation process of this invention, no other binders are involved. Compared with carbon paper processing involving binders, the overlap of pure mesophase pitch-based carbon paper is more reliable and sufficient, thus making the electrical and thermal conductivity of this carbon paper more prominent and obvious. Detailed Implementation

[0044] A method for manufacturing dry-process mesophase pitch-based carbon paper according to the present invention includes the following steps:

[0045] S10. Melt the mesophase asphalt and stir it evenly;

[0046] S20. Molten mesophase pitch is spun into continuous mesophase pitch fibers using a spinning machine.

[0047] In specific implementation, in step S20, mesophase pitch fibers are prepared by spinning. The spinning temperature is 260℃~420℃. The spinning machine spins continuous mesophase pitch fiber filaments at a spin speed of 0.3~80mm / s. The formed mesophase pitch fiber filaments remain continuous in subsequent operation steps and are not cut. After demolding, the mesophase pitch falls in the free space of 30~90cm between the mesh belt and the spinneret.

[0048] S30. After demolding, the continuous long mesophase pitch fiber filaments are stretched, wound, and laid on a temperature-adjustable and moving mesh belt by auxiliary airflow to form a continuous, overlapping three-dimensional mesophase pitch fiber layup.

[0049] In specific implementation, the temperature of the auxiliary airflow in step S30 is 0-90℃. The auxiliary airflow is divided into stretching airflow and turbulent flow. The stretching airflow is located between the spinning die and the mesh belt. The stretching airflow acts on the continuous long mesophase pitch fiber filaments after leaving the die, causing the continuous long mesophase pitch fiber filaments to stretch and wrap. The turbulent flow is set near the surface of the mesh belt. The turbulent flow acts on the stretched continuous long mesophase pitch fiber filaments, causing the continuous long mesophase pitch fiber filaments to wrap further and be laid out disorderly on the mesh belt.

[0050] In this embodiment, the purpose of the auxiliary airflow is to further stretch and coil the mesophase pitch fibers after demolding, and to lay them irregularly on the mesh belt. The specific arrangement of the auxiliary airflow is not limited, as long as the airflow can further stretch the continuous long mesophase pitch fibers along the direction of the airflow. Similarly, the purpose of the turbulence in this embodiment is also to further stretch and coil the stretched mesophase pitch fibers near the mesh belt, and to lay them irregularly on the mesh belt. The temperature of the airflow can be adjusted according to the temperature of the mesophase pitch fibers after demolding to maintain the mesophase pitch fibers within the glass transition temperature range, ensuring they remain stretchable. That is, if the temperature of the mesophase pitch fibers after demolding is too high, the airflow can be adjusted to cool them down, preventing poor stretching. If the temperature is too low, a heated airflow can be used to heat them, maintaining the stretchable state of the mesophase pitch fibers. Furthermore, the airflow arrangement can also promote the dispersion of the stretched mesophase pitch fibers, causing them to intertwine, adhere, and overlap.

[0051] In specific implementation, in step S30, the speed of the conveyor belt can be adjusted to adjust the density and thickness of the mesophase asphalt fiber layup. When laying the mesophase asphalt fiber filaments, the speed of the conveyor belt can be adjusted from 10 to 55 m / min so that the mesophase asphalt fiber can be laid evenly on the conveyor belt. In this embodiment, the temperature of the conveyor belt is adjusted according to the temperature of the stretched mesophase asphalt fiber filaments and the stretching condition. The temperature adjustment range of the conveyor belt is 90-490℃. If the temperature of the mesophase asphalt fiber is too low, the temperature of the conveyor belt needs to be increased so that the mesophase asphalt fiber filaments laid on the conveyor belt can adhere to each other and initially form a three-dimensional layup.

[0052] S40. The mesophase pitch fiber is rolled into a three-dimensional mesophase pitch fiber layer by an adjustable temperature roller. The temperature range of the roller is 140-490℃.

[0053] S41. Between steps S40 and S50, there is also step S41, which is a shaping step. If the rolled layer does not reach the preset thickness and density, the speed of the conveyor belt needs to be reduced; if the rolled layer exceeds the preset thickness and density, the speed of the conveyor belt needs to be increased.

[0054] S50. The mesophase pitch fiber layup is heat-treated under a protective atmosphere to obtain a uniformly cross-linked three-dimensional mesophase pitch fiber layup. In specific implementation, in step S50, the mesophase pitch fiber is heated to 240-470℃ at a rate of 4-19℃ / min.

[0055] S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace in an oxygen-free environment to form carbon paper, with a carbonization temperature of 1100-3500℃.

[0056] In this embodiment, the bulk density of the formed carbon paper is 0.45-0.90 g / cm³. 3 The tensile strength is 33-176 N / cm, and the porosity is 65-95%. The thermal conductivity of the carbon paper at room temperature is ≥3.5 W / (m·K) in the vertical direction and ≥55 W / (m·K) in the parallel direction. The resistivity (surface resistance) of the prepared carbon paper is <3.2 mΩ·cm.

[0057] Example 1

[0058] S10. Melt the mesophase asphalt to 260℃ and stir it evenly;

[0059] S20. Molten mesophase pitch is spun into continuous long mesophase pitch fibers by a spinning machine at a spinning speed of 15 mm / s.

[0060] S30. The distance between the mesh belt and the spinneret is 60cm. After the extrusion of the mold, the continuous long mesophase asphalt fiber filaments along the airflow direction are stretched, wound and laid on the temperature-adjustable and moving mesh belt by the auxiliary airflow. The temperature of the auxiliary airflow is 90℃ and the temperature of the mesh belt is 300℃. The mesh belt travels at a speed of 55m / min to initially form a continuous three-dimensional mesophase asphalt fiber layup.

[0061] S40. The mesophase pitch fiber is rolled at 240°C using an adjustable temperature roller to form a three-dimensional mesophase pitch fiber layup.

[0062] S50. The mesophase pitch fiber layup is heated to 240℃ at a rate of 15℃ / min under a protective atmosphere to obtain a uniformly cross-linked three-dimensional cross-linked mesophase pitch fiber layup.

[0063] S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace at 1100℃ to form carbon paper.

[0064] The resulting carbon paper has a bulk density of 0.45 g / cm³. 3 The tensile strength is 65 N / cm, and the porosity is 93%. The thermal conductivity of the carbon paper at room temperature is 3.7 W / (m·K) in the vertical direction and 59 W / (m·K) in the parallel direction. The resistivity (surface resistance) of the prepared carbon paper is 3.0 mΩ·cm.

[0065] Example 2

[0066] S10. Melt the mesophase asphalt to 350℃ and stir it evenly;

[0067] S20. Molten mesophase pitch is spun into continuous long mesophase pitch fibers by a spinning machine at a spinning speed of 0.5 mm / s.

[0068] S30. The distance between the mesh belt and the spinneret is 60cm. After the extrusion of the mold, the continuous long mesophase asphalt fiber filaments are stretched, wound and laid on the temperature-adjustable and moving mesh belt by the auxiliary airflow. The temperature of the auxiliary airflow is 55℃ and the temperature of the mesh belt is 210℃. The mesh belt travels at a speed of 25m / min to initially form a continuous three-dimensional mesophase asphalt fiber layup.

[0069] S40. The mesophase pitch fiber is rolled at 300°C using an adjustable temperature roller to form a three-dimensional mesophase pitch fiber layup.

[0070] S50. The mesophase pitch fiber layup is heat-treated at a rate of 6℃ / min to 360℃ under a protective atmosphere to obtain a uniformly cross-linked three-dimensional cross-linked mesophase pitch fiber layup.

[0071] S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace at 2500℃ to form carbon paper.

[0072] The resulting carbon paper has a bulk density of 0.67 g / cm³. 3 The tensile strength is 74 N / cm, and the porosity is 88%. The thermal conductivity of the carbon paper at room temperature is 4.5 W / (m·K) in the vertical direction and 75 W / (m·K) in the parallel direction. The resistivity (surface resistance) of the prepared carbon paper is 2.5 mΩ·cm.

[0073] Example 3

[0074] S10. Melt the mesophase asphalt to 420℃ and stir it evenly;

[0075] S20. Molten mesophase pitch is spun into continuous long mesophase pitch fibers at a spinning speed of 0.8 mm / s using a spinning machine.

[0076] S30. The distance between the mesh belt and the spinneret is 60cm. After the extrusion of the mold, the continuous long mesophase asphalt fiber filaments are stretched, wound and laid on the temperature-adjustable and moving mesh belt by the auxiliary airflow. The temperature of the auxiliary airflow is 10℃ and the temperature of the mesh belt is 300℃. The mesh belt travels at a speed of 10m / min to initially form a continuous three-dimensional mesophase asphalt fiber layup.

[0077] S40. The mesophase pitch fiber is rolled at 360° using an adjustable temperature roller to form a three-dimensional mesophase pitch fiber layup.

[0078] S50. The mesophase pitch fiber layup is heat-treated at a rate of 4℃ / min to 470℃ under a protective atmosphere to obtain a uniformly cross-linked three-dimensional cross-linked mesophase pitch fiber layup.

[0079] S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace at 3500℃ in an oxygen-free environment to form carbon paper.

[0080] The resulting carbon paper has a bulk density of 0.86 g / cm³. 3 The tensile strength is 172 N / cm, and the porosity is 76%. The thermal conductivity of the carbon paper at room temperature is 5.3 W / (m·K) in the vertical direction and 80 W / (m·K) in the parallel direction. The resistivity (surface resistance) of the prepared carbon paper is 2.2 mΩ·cm.

[0081] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing dry-process mesophase pitch-based carbon paper, characterized in that, Includes the following steps: S10. Melt the mesophase asphalt and stir it evenly; S20. Molten mesophase pitch is spun into continuous long mesophase pitch fibers using a spinning machine. S30. Assisted airflow causes continuous long mesophase pitch fibers, after demolding, to be stretched, wound, and laid on a temperature-adjustable, moving mesh belt, forming a continuous, overlapping three-dimensional mesophase pitch fiber layup, wherein: The auxiliary airflow is divided into steady stretching airflow and turbulent airflow; The stable drawing airflow is located between the spinning die and the mesh belt. The stable drawing airflow acts on the continuous mesophase pitch fiber filaments after leaving the die, causing the continuous mesophase pitch fiber filaments to be drawn and wrapped. The turbulent airflow is positioned near the surface of the mesh belt, and the turbulent airflow acts on the stretched mesophase pitch fiber filaments, causing the mesophase pitch fiber filaments to further entangle and be laid out disorderly on the mesh belt; The auxiliary airflow is a continuous airflow, which is a steady stretching airflow acting on the mesophase pitch fiber filaments and flows to the surface of the mesh belt and diffuses in all directions to form a turbulent airflow. During the laying of the mesophase pitch fiber filaments, the speed of the mesh belt can be adjusted to adjust the density and thickness of the mesophase pitch fiber layup; S40. The mesophase pitch fiber is rolled by a temperature-adjustable roller to form a fully overlapping three-dimensional mesophase pitch fiber layup. S50. The mesophase pitch fiber layup is subjected to pre-oxidation heat treatment under a protective atmosphere to obtain a uniformly cross-linked and overlapping three-dimensional mesophase pitch fiber layup. S60. The heat-treated and pre-oxidized mesophase asphalt pavement is carbonized in a vacuum furnace in an oxygen-free environment to form carbon paper.

2. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 1, characterized in that: The temperature of the auxiliary airflow in step S30 is 0-90°C.

3. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 1, characterized in that: In step S30, the conveyor belt travel speed is adjustable from 1 to 55 m / min. The temperature adjustment range of the mesh belt in step S30 is 90-490℃; In step S40, the temperature range of the pressure roller is 140-490℃.

4. A method for manufacturing dry-process mesophase pitch-based carbon paper according to any one of claims 1-3, characterized in that: Between steps S40 and S50, there is also step S41, which is a shaping step. If the ply after being rolled by the pressure roller does not reach the preset thickness and density, the speed of the conveyor belt needs to be reduced; if the ply after being rolled exceeds the preset thickness and density, the speed of the conveyor belt needs to be increased.

5. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: The bulk density of the carbon paper in step S60 is 0.45-0.90 g / cm³. 3 .

6. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: The tensile strength of the carbon paper in step S60 is 33-176 N / cm.

7. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: The porosity of the carbon paper in step S60 is 65-95%.

8. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: The thermal conductivity of the carbon paper prepared in step S60 at room temperature is: ≥3.5 W / (m·K) in the vertical direction and ≥55 W / (m·K) in the parallel direction; the resistivity of the prepared carbon paper is <3.2 mΩ·cm.

9. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: In step S20, the mesophase pitch fiber is prepared by spinning. The spinning temperature is 260℃~420℃, the spinning speed is 0.3~80mm / s, and the distance between the mesh belt and the spinneret is 30~90cm.

10. The method for manufacturing dry mesophase pitch-based carbon paper according to claim 4, characterized in that: In step S50, the mesophase pitch fiber is heated to 240-370°C at a rate of 15°C / min and maintained for 45-180 mins in an adjustable speed mesh belt structure device. In step S60, the oxygen-free carbonization temperature in the vacuum furnace is 1100-3500℃.