Carbon fiber graphite composite bipolar plate and preparation method thereof

Abstract

The application discloses a kind of carbon fiber graphite composite bipolar plate and preparation method thereof, belong to fuel cell technical field.The preparation method of the carbon fiber graphite composite bipolar plate, including the following steps: S01: resin is coated on the both sides of carbon fiber cloth with interval, then conductive agent is coated on the resin, to obtain carbon fiber graphite coating material;S02: according to the size of anode and cathode plate assembly cutting, to obtain the cutting carbon fiber graphite coating material;S03: the cutting carbon fiber graphite coating material is placed in mould and is pressed into shape, then demoulding;S04: solidification and shaping are carried out, to obtain carbon fiber graphite composite bipolar plate.The contact resistance of the carbon fiber graphite composite bipolar plate prepared by the application is reduced by 19%-20% compared with the contact resistance of traditional split bipolar plate, and the forming efficiency is increased by 40%;It can effectively reduce the contact resistance of bipolar plate, improve the production efficiency of bipolar plate.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and particularly relates to a carbon fiber-graphite composite bipolar plate and its preparation method. Background Technology

[0002] The bipolar plate of a fuel cell is a core component of the fuel cell stack. Its main functions are to separate the fuel from the oxidant, support the membrane electrode, transport gas through the flow field on the surface, and collect and conduct the current, heat and water generated by the reaction.

[0003] Carbon fiber and graphite composite bipolar plates have great application prospects due to their excellent thermal conductivity, stability and corrosion resistance. Carbon fiber can provide products with very high bending strength.

[0004] However, due to the axial conductivity advantage and poor radial conductivity of carbon fiber, the product has a large through-body resistance, which in turn leads to excessively high internal resistance of the stack, limiting the application of carbon fiber-graphite composite bipolar plates. Summary of the Invention

[0005] This invention provides a carbon fiber-graphite composite bipolar plate and its preparation method, aiming to solve the problems of high contact resistance and low production efficiency of existing carbon fiber-graphite composite bipolar plates.

[0006] The technical solution of this invention is implemented as follows:

[0007] A method for preparing a carbon fiber-graphite composite bipolar plate includes the following steps:

[0008] S01: The resin is applied alternately to both sides of the carbon fiber cloth, and then a conductive agent is applied to the resin to obtain a carbon fiber graphite coated material.

[0009] S02: Cut the carbon fiber graphite coating material according to the dimensions of the anode and cathode plate assembly to obtain the cut carbon fiber graphite coating material.

[0010] S03: The cut carbon fiber graphite coating material is placed in a mold and pressed into shape. After demolding, a crude carbon fiber graphite composite bipolar plate is obtained.

[0011] S04: The crude carbon fiber graphite composite bipolar plate obtained in step S03 is cured and shaped to obtain a carbon fiber graphite composite bipolar plate.

[0012] Preferably, in step S01,

[0013] The resin is preferably an epoxy resin.

[0014] The carbon fiber cloth is either carbon fiber woven fabric or carbon fiber unidirectional tape.

[0015] The coating interval of the interval coating is 0.5mm-0.75mm.

[0016] The conductive agent is one or more of expanded graphite, layered graphite, spherical graphite, tubular graphite, fibrous graphite, graphene, or carbon nanotubes, and the conductive agent is in the form of at least one of powder, block, flake, granule, or slurry. More preferably, the conductive agent is an expanded graphite conductive agent.

[0017] The amount of the conductive agent added is 1wt%-8wt%, based on the total mass of the resin and the conductive agent being 100%.

[0018] Preferably, in step S02,

[0019] The specific dimensions of the anode and cathode plate assembly are as follows: the width is the total width of the cathode plate, the anode plate, and the coating interval width; the length is either the cathode plate length or the anode plate length, wherein the cathode plate length and the anode plate length are equal. The coating interval width mentioned above is 0.5mm-0.75mm.

[0020] The coating interval in the cut carbon fiber graphite coating material is located in the middle of the electrode assembly.

[0021] The coating interval during cutting can be along the short or long side of the electrode plate.

[0022] Preferably, in step S03,

[0023] The pressing is performed using at least one of cold pressing, hot pressing, or hot stamping; the choice of pressing method depends on the selected resin system. More preferably, the pressing temperature is 120-150℃, and the temperature and pressure are maintained for 5 minutes.

[0024] Preferably, in step S04,

[0025] The curing and shaping temperature is 120-150℃. In this application, the curing or shaping temperature is selected according to the characteristics of the chosen resin system.

[0026] A carbon fiber-graphite composite bipolar plate was obtained by the above preparation method.

[0027] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0028] The carbon fiber-graphite composite bipolar plate prepared by this invention is a non-split bipolar plate. The contact resistance of the carbon fiber-graphite composite bipolar plate is reduced by 20% compared to the traditional split bipolar plate, and the molding efficiency is increased by 40%. The carbon fiber-graphite composite bipolar plate prepared by this invention can effectively reduce the contact resistance of bipolar plates and improve the production efficiency of bipolar plates. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0031] Currently, existing carbon fiber-graphite composite bipolar plates suffer from high contact resistance and low production efficiency. To address these technical problems, this invention proposes a carbon fiber-graphite composite bipolar plate and its preparation method.

[0032] Example 1

[0033] A method for preparing a carbon fiber-graphite composite bipolar plate includes the following steps:

[0034] S01: Epoxy resin is applied to both sides of carbon fiber woven fabric at intervals of 0.5 mm, and then expanded graphite conductive agent is applied to the surface of epoxy resin to obtain carbon fiber graphite coated material; the amount of conductive agent added is 8 wt%, based on the total mass of resin and conductive agent being 100%.

[0035] S02: Cut the carbon fiber graphite coating material into pieces. The cutting length is the design size of the electrode plate, and the cutting width is the width of the cathode plate + the width of the anode plate + 0.5 mm. The coating interval is located in the middle of the electrode plate assembly to obtain the cut carbon fiber graphite coating material.

[0036] S03: The cut carbon fiber graphite coating material is placed in a mold at 120°C and pressed into shape. After heat preservation and pressure preservation for 5 minutes, a crude carbon fiber graphite composite bipolar plate is obtained after demolding.

[0037] S04: The crude carbon fiber graphite composite bipolar plate obtained in step S03 is subjected to secondary curing and shaping at a temperature of 150℃ to obtain a carbon fiber graphite composite bipolar plate.

[0038] After testing, the contact resistance of the carbon fiber-graphite composite bipolar plate prepared in Example 1 was reduced by 20% compared to the discrete bipolar plate, and the molding efficiency was increased by 40%.

[0039] Example 2

[0040] A method for preparing a carbon fiber-graphite composite bipolar plate includes the following steps:

[0041] S01: Epoxy resin is applied to both sides of carbon fiber woven fabric at intervals of 0.6 mm, and then expanded graphite conductive agent is applied to the surface of epoxy resin to obtain carbon fiber graphite coated material; the amount of conductive agent added is 1 wt% based on the total mass of resin and conductive agent being 100%.

[0042] S02: Cut the carbon fiber graphite coating material into pieces. The cutting length is the design size of the electrode plate, and the cutting width is the cathode plate width + anode plate width + 0.6mm. The coating interval is located in the middle of the electrode plate assembly to obtain the cut carbon fiber graphite coating material.

[0043] S03: The cut carbon fiber graphite coating material is placed in a mold at 135℃ and pressed into shape. After heat preservation and pressure preservation for 5 minutes, a crude carbon fiber graphite composite bipolar plate is obtained after demolding.

[0044] S04: The crude carbon fiber graphite composite bipolar plate obtained in step S03 is subjected to secondary curing and shaping at a temperature of 150℃ to obtain a carbon fiber graphite composite bipolar plate.

[0045] After testing, the contact resistance of the carbon fiber-graphite composite bipolar plate prepared in Example 1 was reduced by 19% compared to the discrete bipolar plate, and the molding efficiency was increased by 40%.

[0046] Example 3

[0047] A method for preparing a carbon fiber-graphite composite bipolar plate includes the following steps:

[0048] S01: Epoxy resin is applied to both sides of carbon fiber woven fabric at intervals of 0.75 mm, and then carbon nanotube conductive agent is applied to the surface of epoxy resin to obtain carbon fiber graphite coated material.

[0049] S02: Cut the carbon fiber graphite coating material into pieces. The cutting length is the design size of the electrode plate, and the cutting width is the cathode plate width + anode plate width + 0.75mm to obtain the cut carbon fiber graphite coating material.

[0050] S03: Place the cut carbon fiber graphite coating material in a mold at 150°C and press it into shape. Keep it warm and pressurized for 5 minutes. After demolding, a crude carbon fiber graphite composite bipolar plate is obtained.

[0051] S04: The crude carbon fiber graphite composite bipolar plate obtained in step S03 is subjected to secondary curing and shaping at a temperature of 150℃ to obtain a carbon fiber graphite composite bipolar plate.

[0052] After testing, the contact resistance of the carbon fiber-graphite composite bipolar plate prepared in Example 1 was reduced by 20% compared to the discrete bipolar plate, and the molding efficiency was increased by 40%.

[0053] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0054] The carbon fiber-graphite composite bipolar plate prepared by this invention is a non-split bipolar plate. The contact resistance of the carbon fiber-graphite composite bipolar plate is reduced by 19%-20% compared with that of traditional split bipolar plates, and the molding efficiency is increased by 40%. The carbon fiber-graphite composite bipolar plate prepared by this invention can effectively reduce the contact resistance of bipolar plates and improve the production efficiency of bipolar plates.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of making a carbon fiber graphite composite bipolar plate, characterized by: Includes the following steps: S01: The resin is applied alternately to both sides of the carbon fiber cloth, and then a conductive agent is applied to the resin to obtain a carbon fiber graphite coating material; the conductive agent is one or more of expanded graphite, layered graphite, spherical graphite, tubular graphite, and fibrous graphite. S02: Cut the carbon fiber graphite coating material according to the dimensions of the anode and cathode plate assembly to obtain the cut carbon fiber graphite coating material. S03: The cut carbon fiber graphite coating material is placed in a mold and pressed into shape. After demolding, a crude carbon fiber graphite composite bipolar plate is obtained. S04: The crude carbon fiber graphite composite bipolar plate obtained in step S03 is cured and shaped to obtain a carbon fiber graphite composite bipolar plate. In step S01, the coating interval of the spaced coating is 0.5mm-0.75mm; In step S02, the dimensions of the anode and cathode plate assembly are as follows: the width is the total width of the cathode plate, the anode plate, and the coating interval width; the length is the length of the cathode plate or the anode plate, wherein the length of the cathode plate is equal to the length of the anode plate. The coating interval in the cut carbon fiber graphite coating material is located in the middle of the electrode assembly.

2. The method for preparing the carbon fiber-graphite composite bipolar plate according to claim 1, characterized in that: In step S01, the resin is epoxy resin.

3. The method for preparing the carbon fiber-graphite composite bipolar plate according to claim 1, characterized in that: In step S01, the carbon fiber cloth is either carbon fiber woven cloth or carbon fiber unidirectional tape.

4. The method for preparing the carbon fiber-graphite composite bipolar plate according to claim 1, characterized in that: In step S01, the amount of conductive agent added is 1wt%-8wt%, based on the total mass of resin and conductive agent being 100%.

5. The method for preparing the carbon fiber-graphite composite bipolar plate according to claim 1, characterized in that: In step S03, the pressing is performed by at least one of cold pressing, hot pressing, or hot stamping.

6. The method of claim 1, wherein: The pressing temperature is 120-150℃, and the temperature and pressure are maintained for 5 minutes.

7. The method for preparing the carbon fiber-graphite composite bipolar plate according to claim 1, characterized in that: In step S04, the curing and shaping temperature is 120-150℃.

8. A carbon fiber graphite composite bipolar plate is prepared by the method described in any one of claims 1-7.