Preparation method of composite graphite bipolar plate

A technology of composite graphite and bipolar plates, which can be used in flat products, final product manufacturing, sustainable manufacturing/processing, etc., and can solve problems such as insufficient mechanical strength, brittle graphite plates, and proportional contradictions.

Pending Publication Date: 2021-01-29
JIANGSU QINGNENG NEW ENERGY TECHNOLOGIES CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Pure flexible graphite bipolar plates are thinner than metal plates, light in weight, corrosion-resistant, low in material cost and production cost, but due to the brittleness, fragility and insufficient mechanical strength of graphite plates, high protection requirements are required during transportation
Existing composite graphite plates are composed of conductive fillers and polymers. The conductive fillers are generally natural graphite, artificial graphite, expanded graphite, etc. Expanded graphite has the advantages of flexibility, easy processing and air tightness, but the strength and air tightness of pure expanded graphite plates If the properties cannot meet the corresponding requirements, resin needs to be added to improve the mechanical strength and air tightness; the high conductivity requirements of the bipolar plate need to increase its graphite content, and the requirements for air tightness and mechanical strength need to increase its resin content, so that graphite and Resin ratios contradict each other
At present, the production of bipolar plates is done by manual operation, and it is impossible to realize the automation or semi-automation of the production process.
Due to the use of manual machining operations, large-scale production cannot be realized, the efficiency is low, and the labor intensity is high, which greatly increases the labor cost in the preparation process; and the entire process requires high operating skills of the operators. During the entire production process, the product The consistency of quality cannot be effectively guaranteed

Method used

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  • Preparation method of composite graphite bipolar plate

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Effect test

preparation example Construction

[0026] The present application provides a method for preparing a composite graphite bipolar plate. The method of the present application comprises the following steps: 1. prepare expanded graphite from graphite ore; 2. mix selected resin and auxiliary conductive filler to obtain a mixture of resin and auxiliary conductive filler, which is recorded as the first mixture; 3. prepare the The mixture of expanded graphite, resin and auxiliary conductive filler is uniformly mixed by dry mixing, and is recorded as the second mixture; ④ Press the second mixture into a low-density prefabricated board; ⑤ The low-density prefabricated board is molded into a The unipolar plate of the field, wherein the unipolar plate includes a hydrogen flow field unipolar plate and an oxygen flow field unipolar plate; ⑥ the unipolar plate is vacuum impregnated; ⑦ the hydrogen flow field unipolar plate is mixed with oxygen The flow field unipolar plate is bonded with an adhesive (by molding) by screen prin...

Embodiment 1

[0074] 1) Take 2000g of graphite ore raw material and expand it instantly in a high-temperature furnace at 1050°C until the expansion volume reaches 180ml / g, and the expansion multiple is 270 times. It is shaped by a graphite shaping machine, and the shaping time is 10-15 minutes. After shaping, the long diameter of the expanded graphite is reduced by 40-50%.

[0075] 2) dry-blending 60 wt% of phenolic resin powder meeting the particle size requirement after grinding and sieving with 40 wt% of carbon black / carbon fiber, and mixing uniformly to obtain the first mixture.

[0076] 3) Proportionally mix the first mixture with the existing expanded graphite in an appropriate proportion, wherein the expanded graphite is 50wt%; the mixing time is 10-30min with a mixer to prepare the second mixture.

[0077] 4) Continue to add 8wt% acicular ore powder to the mixture of expanded graphite, phenolic resin, and carbon black / carbon fiber. In this example, calcite powder is used. The averag...

Embodiment 2

[0085] 1) Take 2000g of graphite ore raw material and expand it instantly in a high-temperature furnace at 1200°C until the expansion volume reaches 200ml / g, and the expansion factor is 300 times. It is shaped by a graphite shaping machine, and the shaping time is 10-15 minutes. After shaping, the long diameter of the expanded graphite is reduced by 40-50%.

[0086] 2) Dry-blending the epoxy resin powder (65wt%) meeting the particle size requirements after grinding and sieving with the mesophase carbon microspheres (35wt%), and mixing uniformly to prepare the first mixture.

[0087] 3) Proportionally mix the first mixture with an appropriate proportion and the existing expanded graphite, wherein the expanded graphite is 70wt%, and the mixing time is 10-30min with a mixer to prepare the second mixture.

[0088] 4) Continue to add 7wt% acicular ore powder to the mixture of expanded graphite, phenolic resin, and carbon black / carbon fiber. In this example, calcite powder is used. ...

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Abstract

The invention discloses a preparation method of a composite graphite bipolar plate. The preparation method comprises the following steps: by using graphite ore as a raw material, preparing expanded graphite at high temperature; mixing resin with an auxiliary conductive filler to obtain a first mixture; performing dry mixing on the expanded graphite and the first mixture to obtain a second mixture,and pressing the second mixture into a low-density prefabricated slab; carrying out mould pressing on the low-density prefabricated slab, and pressing a flow field on the upper surface or the upper and lower surfaces to manufacture a semi-finished monopole plate comprising a hydrogen flow field monopole plate and an oxygen flow field monopole plate; carrying out vacuum impregnation on the semi-finished monopole plate; and bonding the hydrogen flow field monopole plate and the oxygen flow field monopole plate by using a silk-screen printing technology through a bonding agent (mould pressing) to form a bipolar plate, and heating and curing to obtain the composite graphite bipolar plate. A compression molding process is adopted, so that the preparation method is more suitable for batch production, shortens the processing period and reduces the production cost; and the composite graphite bipolar plate is excellent in various performance indexes such as conductivity, density, air tightness, mechanical lightness and corrosion resistance.

Description

technical field [0001] The invention relates to the technical field of fuel cells, in particular to a preparation method of a composite graphite bipolar plate. Background technique [0002] Hydrogen fuel cell is a kind of proton exchange membrane fuel cell, which is equivalent to the "reverse" device of water electrolysis in principle. Its single cell is composed of bipolar plates and membrane electrodes. The voltage of a single battery is generally 0.3-1.0V, which is very low, so in practical applications, tens or hundreds of single batteries are used in series. Among them, the role of the bipolar plate mainly includes: providing the current path between adjacent single cells, the distribution channel of the reactant gas, the cooling channel, separating the fuel, coolant (water) and oxidant supplied to the single cell, and separating the adjacent cells. Fuel gas and oxidizing gas provide the mechanical strength necessary for the stability of the cell stack structure. [...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M8/0213H01M8/0221H01M8/0226H01M8/0258B29B7/00B29B11/12B29D7/00
CPCH01M8/0213H01M8/0221H01M8/0226H01M8/0258B29B7/002B29B11/12B29D7/00Y02E60/50Y02P70/50
Inventor 顾志军陈杰
Owner JIANGSU QINGNENG NEW ENERGY TECHNOLOGIES CO LTD
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