Method for preparing graphite/resin compound bipolar plate for fuel cell

A bipolar plate and resin technology, which is applied in the direction of battery electrodes, circuits, electrical components, etc., can solve the problems of flexural strength, influence of electrical conductivity, influence of flexural strength and electrical conductivity, and tightness of bipolar plate compression, etc., to achieve Improve overall performance, reduce adverse effects, and have strong practicability

Active Publication Date: 2010-10-13
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, experiments have found that the composite powder produced by this mixing method is processed into a bipolar plate. When the bipolar plate is observed under a scanning electron microscope, it can be seen that there are resin aggregation areas and graphite aggregation areas in it, and there are local Therefore, the bipolar plate is not pressed tightly, and its flexural strength and electrical conductivity are greatly affected; and, in the prior art, inorganic fillers and organic polymer binders are directly used without other auxiliary reagents. Due to the significant difference in the chemical structure and physical form of these two types of substances, the lack of affinity between the two also makes the bonding interface between the graphite and the resin of the final bipolar plate loose, there are holes, and the compression is not tight. Greatly affect its flexural strength and electrical conductivity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Example 1 Add 10 g of absolute ethanol solution into a container with 14.3 g of phenolic resin, and ultrasonically in an ultrasonic cleaner for 5 minutes to fully dilute the resin. Then add 2.5g of additive carbon black, ultrasonically disperse in an ultrasonic cleaner for 20 minutes, then add 37.5g of conductive filler graphite powder and stir for 10 minutes, add 50ml of distilled water, then place the container in an ultrasonic oscillator for ultrasonic dispersion, and mechanically The stirrer stirred for 1 hour, the stirring frequency was 4500 rpm, and the ultrasonic frequency was 80KHz. After the materials are uniformly mixed, the slurry-like mixture is taken out and placed in a blast drying oven at a constant temperature of 40° C. for drying; then the above-mentioned mixture is subjected to molding-curing steps to obtain a bipolar plate. Molding conditions: pressure 160MPa, pressure holding time 5min, curing program: 80°C-100°C-120°C-140°C-160°C-180°C, heat preser...

Embodiment 2

[0014] _ Example 2 Adopt the substantially identical technological process of embodiment 1, difference is that, the one, molding pressure is 200MPa, and molding pressure holding time 3min; The 2nd, first will carry out surface pretreatment to conductive filler graphite powder, and method is as follows: add 60 gram of graphite, 54 milliliters of absolute ethanol, 6 milliliters of distilled water, 0.54 gram of γ-aminopropyltriethoxysilane coupling agent, that is, the amount of coupling agent added is 0.9% of the graphite mass, and the container is placed in an ultrasonic oscillator , while stirring mechanically for 30 minutes, and then drying in an oven at 80°C to obtain surface-pretreated graphite powder.

[0015] The flexural strength of the bipolar plate made by the method of this embodiment can reach 42.9MPa, which is nearly 20% higher than that of the 36.6MPa without coupling agent pretreatment, and the electrical conductivity is reduced, but the magnitude of reduction is ...

Embodiment 3

[0016] _ Example 3 Using the process as in Example 2, the coupling agent is γ-methacryloxypropyltrimethylsilane, and the addition amounts are 0, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0% %, the ultrasonic frequency is 40KHz, and the mechanical stirring frequency is 3000 rpm to investigate the influence of the amount of coupling agent added on the performance of the bipolar plate in the pretreatment method. The results are shown in Table 2. It can be seen from the table that with the increase of the silane coupling dose, the density changes little. It can be seen that when the graphite is pretreated with the silane coupling agent, the amount of the coupling agent has little effect on the density of the bipolar plate. With the increase of the amount of silane coupling agent, the conductivity of the bipolar plate tends to decrease within a certain range, while the flexural strength first increases and then decreases, and reaches the maximum value of 42.9 when the content of the couplin...

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Abstract

The invention provides a method for preparing a bipolar plate, which comprises the following steps of: dissolving binder into organic solvent, adding carbon black serving as additive, ultrasonically dispersing the mixture in an ultrasonic machine, adding required graphite conductive filler and water into the mixture, and then ultrasonically dispersing the mixture in the ultrasonic machine, stirring the mixture at the same time, and drying the mixture, wherein the ultrasonic frequency is between 20 and 80kHz; and crushing the mixture, and obtaining the bipolar plate by a molding-curing process. The method improves wetting property between inorganic conductive objects and organic polymer, and can also use a coupling agent. The method makes all the materials uniformly mixed and improves conductivity of the bipolar plate prepared by the method by near 70 percent.

Description

technical field [0001] The invention relates to a preparation method of a composite material, in particular to a preparation method of a graphite / resin composite bipolar plate for a fuel cell. Background technique [0002] At present, in the technology of making bipolar plates by one-time molding method, thermosetting or thermoplastic resin organic matter is used as binder, graphite or carbon black inorganic filler is used as conductive aggregate, the above materials are mixed evenly after pretreatment, and dried - Crushing and sieving to prepare composite powder, and then mold the powder at one time by molding methods such as molding, extrusion or injection to obtain composite bipolar plates of various shapes and sizes with flow fields. In the above composite powder preparation process, mechanical mixing is generally used. However, experiments have found that the composite powder produced by this mixing method is processed into a bipolar plate. When the bipolar plate is ob...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/88
CPCY02E60/50
Inventor 刘洪波陈惠李建新
Owner HUNAN UNIV
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