CN114559579A - High-density flexible graphite bipolar plate and preparation method and application thereof - Google Patents
High-density flexible graphite bipolar plate and preparation method and application thereof Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 131
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 131
- 239000010439 graphite Substances 0.000 title claims abstract description 131
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000011347 resin Substances 0.000 claims abstract description 44
- 229920005989 resin Polymers 0.000 claims abstract description 44
- 238000005470 impregnation Methods 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 27
- 239000000446 fuel Substances 0.000 claims abstract description 16
- 238000000748 compression moulding Methods 0.000 claims abstract description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 30
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 30
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 21
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 13
- 238000004140 cleaning Methods 0.000 claims description 11
- 239000002904 solvent Substances 0.000 claims description 11
- 238000007711 solidification Methods 0.000 claims description 8
- 239000004925 Acrylic resin Substances 0.000 claims description 6
- 239000003822 epoxy resin Substances 0.000 claims description 6
- 238000011068 loading method Methods 0.000 claims description 6
- 229920000647 polyepoxide Polymers 0.000 claims description 6
- 238000003825 pressing Methods 0.000 claims description 6
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 5
- 238000007598 dipping method Methods 0.000 claims description 5
- 229920001568 phenolic resin Polymers 0.000 claims description 5
- 239000005011 phenolic resin Substances 0.000 claims description 5
- 238000007865 diluting Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 230000008023 solidification Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 5
- 238000002156 mixing Methods 0.000 abstract description 3
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- 239000002994 raw material Substances 0.000 description 14
- 239000007789 gas Substances 0.000 description 11
- 239000000110 cooling liquid Substances 0.000 description 8
- 230000008595 infiltration Effects 0.000 description 8
- 238000001764 infiltration Methods 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- 239000001257 hydrogen Substances 0.000 description 7
- 229910052739 hydrogen Inorganic materials 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 230000035699 permeability Effects 0.000 description 5
- 230000001133 acceleration Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
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- 230000000052 comparative effect Effects 0.000 description 3
- 238000007723 die pressing method Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
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- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B15/00—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00
- B29B15/08—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00 of reinforcements or fillers
- B29B15/10—Coating or impregnating independently of the moulding or shaping step
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B15/00—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00
- B29B15/08—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00 of reinforcements or fillers
- B29B15/10—Coating or impregnating independently of the moulding or shaping step
- B29B15/12—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length
- B29B15/122—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length with a matrix in liquid form, e.g. as melt, solution or latex
- B29B15/125—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length with a matrix in liquid form, e.g. as melt, solution or latex by dipping
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/40—Shaping or impregnating by compression not applied
- B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
- B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0204—Non-porous and characterised by the material
- H01M8/0213—Gas-impermeable carbon-containing materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0204—Non-porous and characterised by the material
- H01M8/0221—Organic resins; Organic polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0204—Non-porous and characterised by the material
- H01M8/0223—Composites
- H01M8/0226—Composites in the form of mixtures
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a high-density flexible graphite bipolar plate and a preparation method and application thereof.A low-viscosity diluted resin solution is used for mixing and pretreating flexible expanded graphite, and a resin impregnation post-treatment process after compression molding is combined, so that resin is uniformly distributed in the flexible graphite bipolar plate, the porosity in the bipolar plate is effectively reduced, the strength and the air tightness of the bipolar plate are improved, the high-density flexible graphite bipolar plate is finally obtained, and the working efficiency and the service life of a fuel cell are improved. The flexible graphite bipolar plate prepared by the low-viscosity dilute resin solution pretreatment method has the advantages of simple preparation process and low cost, is particularly suitable for rapid batch treatment, and is suitable for popularization and application in the field of flexible graphite bipolar plates of fuel cells.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a high-density flexible graphite bipolar plate and a preparation method and application thereof.
Background
Hydrogen is the most widely distributed element in the universe, and due to the physical and chemical characteristics of hydrogen elements, hydrogen becomes a secondary clean energy which is widely concerned, has the advantages of high energy density, wide and rich sources, environmental protection and the like, and is a recognized clean zero-carbon energy. The hydrogen fuel cell using hydrogen as fuel has the characteristics of high energy conversion efficiency, environmental friendliness, quick start at room temperature and the like. Meanwhile, through a combined heat and power generation system, the energy utilization efficiency can be further improved, the method is regarded as one of main paths for converting an energy system into sustainable development, and the method has great potential for wide application.
The bipolar plate is an important component of a hydrogen fuel cell, and mainly has the functions of isolating and distributing oxidant and fuel, conducting current, supporting a membrane electrode, adjusting the internal temperature of a stack and the like, and the performance requirements in the aspects of electric conduction, bending strength, corrosion resistance and the like need to be met. In order to meet the operational requirements of hydrogen fuel cells, the bipolar plates must have good gas tightness, electrical and corrosion resistance, good thermal conductivity and mechanical properties. The flexible graphite bipolar plate which uses the low-cost expanded graphite plate as the base material and adopts the rapid die pressing processing procedure of the die has simple manufacturing process and is suitable for mass production. The common process for processing the flexible graphite bipolar plate by mould pressing can be referred to Chinese patent application with publication number CN 112310426A, which discloses a preparation method of the graphite bipolar plate and the graphite bipolar plate, comprising the following steps: firstly, flake graphite is fed intoIntercalation treatment is carried out, expansion graphite is obtained by instantaneous expansion at high temperature, the expansion graphite is pre-pressed into plates with different densities, pressure or vacuum impregnation is carried out in a low-viscosity organic solvent containing resin, then the plates after surface treatment are heated in an oven to evaporate and remove the solvent, and a flow field is molded under the vacuum condition and the bipolar plates are solidified and formed. By adopting the technical scheme of the invention, the density of the prepared graphite bipolar plate is 1.0-2.0 g/cm3And the tensile strength of the bipolar plate subjected to the dipping treatment is 25-35 MPa.
For another example, a chinese patent application with publication number CN 109950569 a discloses a method for manufacturing a bipolar plate of a fuel cell by die pressing, which comprises the following steps: selecting expanded graphite, shaping the expanded graphite, placing the shaped expanded graphite in a mould of isostatic pressing equipment for pressing to obtain the bipolar plate with a flow field, impregnating resin, rinsing, curing with hot water or drying and curing to obtain the bipolar plate. The invention improves the uniformity of the gaps of the bipolar plate after die pressing and the uniformity of the density of the die-pressed plate, the density uniformity is within +/-1 percent, and the thinnest of the bipolar plate can reach 0.5 mm.
However, the mechanical strength and air tightness of the fuel cell bipolar plate prepared by the existing processes are still not ideal.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a preparation method of a flexible graphite bipolar plate with higher mechanical strength and better air tightness.
In order to achieve the purpose, the invention adopts the following technical scheme.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) And (2) carrying out mixed impregnation pretreatment on the flexible expanded graphite plate which is not subjected to mould pressing treatment and a dilute resin solution at a vacuum degree of-0.9 bar or higher, wherein the mixed impregnation pretreatment time is 10-30 minutes, and carrying out a surface cleaning step after the pretreatment is finished.
2) And performing semi-curing treatment on the cleaned flexible expanded graphite plate.
3) And (3) placing the semi-cured flexible expanded graphite plate in a mould for compression molding to form the prefabricated graphite bipolar plate.
4) And (3) immersing the dilute resin solution into the prefabricated graphite bipolar plate by a vacuum impregnation method, cleaning the surface of the bipolar plate after the impregnation is finished, and then carrying out curing treatment to obtain the high-density flexible graphite bipolar plate product.
Wherein the solid content of the dilute resin solution is 3-12%.
The temperature of the semi-solidification treatment is 15-30 ℃, and the solidification time is 1-30 min.
More preferably, the density of the flexible expanded graphite sheet is in the range of 0.04 to 0.12g/cm3In the meantime.
More preferably, the resin of the dilute resin solution is a mixture of one or more of epoxy resin, polyacrylic resin and phenolic resin, and the solvent for diluting the resin is one or more of methanol, ethanol, isopropanol and glycerol mixed according to different proportions.
More preferably, the mixing ratio of the solvents is in the range of: 2-80% of methanol, 2-70% of ethanol, 0-60% of isopropanol and 0-60% of glycerol by volume percentage.
More preferably, the prefabricated graphite bipolar plate has a thickness of 4-8mm and a density of 0.08-0.18g/cm3。
More preferably, the loading ratio of the resin after impregnation of the prefabricated graphite bipolar plate is in the range of 25 to 65 wt%.
More preferably, the curing temperature is 60-120 ℃, and the curing time is 20-120 min.
The invention also provides a high-density flexible graphite bipolar plate which is prepared by the preparation method.
The invention also provides application of the high-density flexible graphite bipolar plate in a fuel cell.
Compared with the prior art, the invention has the following advantages and beneficial effects.
1) The flexible expanded graphite plate which is not subjected to mould pressing treatment is subjected to impregnation pretreatment under the vacuum degree of-0.9 bar or higher by using a dilute resin solution, and a secondary impregnation process of resin is performed after mould pressing, so that the resin is more uniformly distributed in the bipolar plate, tiny pores in the bipolar plate are filled, the internal porosity is effectively reduced, and the strength and the air tightness of the bipolar plate are improved. Through actual production detection, the bending strength of the flexible graphite bipolar plate prepared by the method reaches 32MPa, and the tensile strength of the flexible graphite bipolar plate is 45 MPa; gas permeability 4000 hours the helium permeability at the end of the life acceleration experiment could not be detected; the mechanical strength and the air tightness are far superior to those of the prior art. The internal resistance of the fuel cell can be reduced, the working efficiency of the fuel cell can be improved, and the service life of the fuel cell can be prolonged.
2) The resin pretreatment method used in the invention is simple, has low cost, is especially suitable for rapid batch treatment, and is suitable for popularization and application in the field of flexible graphite bipolar plates of fuel cells.
Drawings
Fig. 1 is a schematic flow chart of a method for preparing a high-density flexible graphite bipolar plate according to the invention.
Detailed Description
The following describes the embodiments of the present invention with reference to the drawings of the specification, so that the technical solutions and the advantages thereof are more clear and clear. The embodiments described below are exemplary and are intended to be illustrative of the invention, but are not to be construed as limiting the invention.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
As shown in fig. 1, a method for preparing a high-density flexible graphite bipolar plate has the following preparation principle.
The first step1, under the condition of high vacuum, the flexible expanded graphite plate which is not molded is mixed with dilute resin solution for infiltration pretreatment, the time of the mixed infiltration pretreatment is 10-30 minutes, and the surface resin cleaning step is carried out after the pretreatment is finished.
And step2, performing semi-curing treatment on the cleaned flexible expanded graphite plate to obtain a certain flexible graphite plate raw material.
And step3, performing compression molding on the semi-cured graphite plate raw material in a mold with a gas flow passage and a cooling liquid flow passage to form the prefabricated graphite bipolar plate.
And step4, dipping the diluted resin solution into the prefabricated graphite bipolar plate by vacuum impregnation.
And a fifth step5, removing excessive dilute resin solution, cleaning the surface of the prefabricated graphite bipolar plate, and then carrying out curing treatment to finally obtain the high-density flexible graphite bipolar plate.
Wherein, in the first step1, the high vacuum condition means a vacuum degree of-0.9 bar or more, and the positive and negative are based on a standard atmospheric pressure. The solid content of the dilute resin solution is 3-12%.
In the second step2, the semi-curing temperature is 15-30 ℃, and the curing time is 1-30 min.
In the third step3, the mold used for press molding may be any of various molds known in the art or available in the future, and the arrangement of the gas flow passage and the cooling liquid flow passage may be adjusted according to actual needs; this is the general technical knowledge known to the person skilled in the art.
In the fourth step4, the vacuum impregnation method is conventional, and the vacuum impregnation time is generally 3 to 12 hours; reference may be made to the prior art mentioned in the background, etc., which will not be described in detail herein.
In the fifth step5, the curing temperature is 60-120 deg.C and the curing time is 20-120 min.
Example 1.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.06g/cm3The flexible expanded graphite plate is uniformly mixed with an epoxy resin ethanol solution with the solid content of 5 percent, and pre-infiltration treatment is carried out for 30min under the vacuum degree of minus 0.9bar or higher; after the completion of the pre-impregnation, the surface resin was washed with water at normal temperature.
2) And (3) performing semi-solidification treatment on the cleaned flexible expanded graphite plate for 20min at the temperature of 20 ℃ to obtain a graphite plate raw material with certain flexibility.
3) The graphite plate raw material is subjected to compression molding in a mold with a gas flow passage and a cooling liquid flow passage to obtain the graphite plate raw material with the density of 0.10g/cm3And the prefabricated graphite bipolar plate with the thickness of 5 mm.
4) And (3) immersing the epoxy resin ethanol solution with the solid content of 5% into the prefabricated graphite bipolar plate by a vacuum impregnation method, and removing the excessive resin solution and cleaning the surface of the prefabricated graphite bipolar plate after the impregnation is finished. After the treatment of this step, the resin loading ratio of the prefabricated graphite bipolar plate was about 35 wt%.
5) And (3) curing the prefabricated graphite bipolar plate treated in the step (4) at 70 ℃ for 100 minutes to obtain the high-density flexible graphite bipolar plate 1.
Example 2.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.04g/cm3The flexible expanded graphite plate is uniformly mixed with a phenolic resin solution with the solid content of 7 percent, and pre-infiltration treatment is carried out for 20min under the vacuum degree of minus 0.9bar or higher; after the completion of the pre-impregnation, the surface resin was washed with water at normal temperature. In the step, the solvents used for the phenolic resin solution are 50% methanol and 50% ethanol in terms of volume ratio.
2) And (3) performing semi-solidification treatment on the cleaned flexible expanded graphite plate for 30min at 15 ℃ to obtain a graphite plate raw material with certain flexibility.
3) The graphite plate raw material is subjected to compression molding in a mold with a gas flow passage and a cooling liquid flow passage to obtain the graphite plate raw material with the density of 0.08g/cm3And the thickness of the prefabricated graphite bipolar plate is 6 mm.
4) And (3) immersing a phenolic resin solution with solid content of 7%, 50% methanol and 50% ethanol as solvents into the prefabricated graphite bipolar plate by a vacuum impregnation method, and removing excessive resin solution and cleaning the surface of the prefabricated graphite bipolar plate after the impregnation is finished. After the treatment of the step, the resin loading ratio of the prefabricated graphite bipolar plate is about 45 wt%.
5) And (3) curing the prefabricated graphite bipolar plate treated in the step (4) at 90 ℃ for 80 minutes to obtain the high-density flexible graphite bipolar plate 2.
Example 3.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.10g/cm3The flexible expanded graphite plate is uniformly mixed with polyacrylic resin solution with solid content of 8 percent, and pre-infiltration treatment is carried out for 10min under the vacuum degree of minus 0.9bar or higher; after the completion of the pre-impregnation, the surface resin was washed with water at normal temperature. In the step, solvents adopted by the polyacrylic resin solution are 30% of methanol, 30% of ethanol, 20% of isopropanol and 20% of glycerol according to volume ratio.
2) And (3) performing semi-solidification treatment on the cleaned flexible expanded graphite plate for 16min at 25 ℃ to obtain a graphite plate raw material with certain flexibility.
3) The graphite plate raw material is subjected to compression molding in a mold with a gas flow passage and a cooling liquid flow passage to obtain the graphite plate raw material with the density of 0.15g/cm3And the thickness of the prefabricated graphite bipolar plate is 4 mm.
4) And (3) immersing resin solution with solid content of 8 percent, solvent of 30 percent methanol, 30 percent ethanol, 20 percent isopropanol and 20 percent glycerol into the prefabricated graphite bipolar plate by a vacuum impregnation method, and removing excessive resin solution and cleaning the surface of the bipolar plate after the impregnation is finished. After the treatment of this step, the resin loading ratio of the prefabricated graphite bipolar plate is about 55 wt%.
5) And (3) curing the prefabricated graphite bipolar plate treated in the step (4) at 100 ℃ for 30 minutes to obtain the high-density flexible graphite bipolar plate 3.
Example 4.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.12g/cm3The flexible expanded graphite plate is uniformly mixed with polyacrylic resin solution with the solid content of 12 percent, and pre-infiltration treatment is carried out for 25min under the vacuum degree of-0.9 bar or higher; cleaning surface tree with normal temperature water after pre-impregnationAnd (3) fat. In the step, solvents of the polyacrylic resin solution are 30% methanol, 30% ethanol, 20% isopropanol and 20% glycerol.
2) And (3) performing semi-solidification treatment on the cleaned flexible expanded graphite plate for 15min at the temperature of 30 ℃ to obtain a graphite plate raw material with certain flexibility.
3) The graphite plate raw material is subjected to compression molding in a mold with a gas flow passage and a cooling liquid flow passage to obtain the graphite plate raw material with the density of 0.18g/cm3And the thickness of the prefabricated graphite bipolar plate is 8 mm.
4) And (3) soaking a resin solution with the solid content of 8% and the solvents of 70% methanol, 10% ethanol and 10% isopropanol into the prefabricated graphite bipolar plate by a vacuum impregnation method, and removing the excessive resin solution and cleaning the surface of the prefabricated graphite bipolar plate after the impregnation is finished. After the treatment of this step, the resin loading ratio of the prefabricated graphite bipolar plate is about 55 wt%.
5) And (3) curing the prefabricated graphite bipolar plate treated in the step (4) at 120 ℃ for 20 minutes to obtain the high-density flexible graphite bipolar plate (4).
Comparative example 1.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.06g/cm3The flexible expanded graphite plate is uniformly mixed with an epoxy resin ethanol solution with the solid content of 5 percent, and pre-infiltration treatment is carried out for 10 hours under the vacuum degree of-0.1 bar; after the completion of the pre-impregnation, the surface resin was washed with water at normal temperature.
2) The cleaned flexible expanded graphite plate is subjected to compression molding in a mold with gas and cooling liquid flow passages to obtain the product with the density of 0.10g/cm3And the thickness of the prefabricated graphite bipolar plate is 5 mm.
3) And (3) curing the prefabricated graphite bipolar plate for 100 minutes at 70 ℃ to obtain the flexible graphite bipolar plate A.
Comparative example 2.
A preparation method of a high-density flexible graphite bipolar plate comprises the following steps.
1) The density is 0.06g/cm3The flexible expanded graphite plate is subjected to compression molding in a mold with gas and cooling liquid flow passages to obtain the flexible expanded graphite plate with the density of 0.10g/cm3And the thickness of the prefabricated graphite bipolar plate is 5 mm.
2) Uniformly mixing the prefabricated graphite bipolar plate with an epoxy resin ethanol solution with the solid content of 5%, and performing pre-impregnation treatment for 10 hours under the vacuum degree of-0.1 bar; after the completion of the pre-impregnation, the surface resin was washed with water at normal temperature.
3) And (3) curing the prefabricated graphite bipolar plate for 100 minutes at 70 ℃ to obtain the flexible graphite bipolar plate B.
And (5) testing the performance.
The flexible graphite bipolar plates manufactured in examples 1 to 4 and comparative examples 1 to 2 were subjected to flexural strength, tensile strength, and airtightness tests (gas permeability 4000 hour life acceleration test). The test results are shown in table 1.
TABLE 1 Performance test Table for each flexible graphite bipolar plate
As can be seen from Table 1, the flexible graphite bipolar plate treated by the method has bending strength as high as 32MPa, tensile strength as high as 45MPa and mechanical strength far superior to that of the prior art.
The helium permeability of the flexible graphite bipolar plate treated by the method can not be detected after the 4000-hour service life acceleration experiment, compared with the helium permeability detected after the 4000-hour service life acceleration experiment only by adopting a one-time infiltration process. Therefore, the air tightness of the flexible graphite bipolar plate prepared by the invention is obviously superior to that of the prior art.
From the above description of the principles, it will be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments described above, and that modifications and alterations based on the present invention using techniques known in the art are within the scope of the present invention, which is defined by the claims and their equivalents. The details not described in the detailed description are prior art or common general knowledge.
Claims (9)
1. A preparation method of a high-density flexible graphite bipolar plate is characterized by comprising the following steps:
1) carrying out mixed impregnation pretreatment on a flexible expanded graphite plate which is not subjected to mould pressing treatment and a dilute resin solution under the vacuum degree of-0.9 bar or higher, wherein the mixed impregnation pretreatment time is 10-30 minutes, and carrying out a surface cleaning step after the pretreatment is finished;
2) semi-curing the cleaned flexible expanded graphite plate;
3) placing the semi-cured flexible expanded graphite plate in a mold for compression molding to form a prefabricated graphite bipolar plate;
4) dipping the dilute resin solution into the interior of the prefabricated graphite bipolar plate by a vacuum dipping method, cleaning the surface of the bipolar plate after dipping, and then carrying out curing treatment to obtain a high-density flexible graphite bipolar plate product;
the solid content of the dilute resin solution is 3-12%;
the temperature of the semi-solidification treatment is 15-30 ℃, and the solidification time is 1-30 min.
2. The method for preparing a high-density flexible graphite bipolar plate as claimed in claim 1, wherein the density of the flexible expanded graphite plate is 0.04-0.12g/cm3In the meantime.
3. The method for preparing a high-density flexible graphite bipolar plate according to claim 1, wherein the resin of the diluted resin solution is a mixture of one or more of epoxy resin, polyacrylic resin and phenolic resin, and the solvent for diluting the resin is one or more of methanol, ethanol, isopropanol and glycerol mixed according to different proportions.
4. The method for preparing a high-density flexible graphite bipolar plate as claimed in claim 3, wherein the solvent is mixed in a ratio ranging from: 2-80% of methanol, 2-70% of ethanol, 0-60% of isopropanol and 0-60% of glycerol by volume percentage.
5. The method for preparing a high-density flexible graphite bipolar plate as claimed in claim 1, wherein the prefabricated graphite bipolar plate has a thickness of 4-8mm and a density of 0.08-0.18g/cm3。
6. The method for preparing a high-density flexible graphite bipolar plate as claimed in claim 1, wherein the resin loading ratio ranges from 25 to 65wt% after the impregnation of the prefabricated graphite bipolar plate is finished.
7. The method for preparing a high-density flexible graphite bipolar plate according to claim 1, wherein the curing temperature is 60-120 ℃ and the curing time is 20-120 min.
8. A high-density flexible graphite bipolar plate, which is prepared by the preparation method as claimed in any one of claims 1 to 7.
9. Use of a high density flexible graphite bipolar plate according to claim 8 in a fuel cell.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115954496A (en) * | 2022-08-31 | 2023-04-11 | 江苏金亚隆科技有限公司 | Flexible graphite bipolar plate |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1997510A (en) * | 2004-02-26 | 2007-07-11 | 先进能源科技公司 | Treatment of flexible graphite material and method thereof |
| US20080220154A1 (en) * | 2007-03-06 | 2008-09-11 | Gallagher Emerson R | Method of forming fluid flow field plates for electrochemical devices |
| CN112310426A (en) * | 2020-10-10 | 2021-02-02 | 滨州双峰石墨密封材料有限公司 | Preparation method of graphite bipolar plate and graphite bipolar plate prepared by preparation method |
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2022
- 2022-02-16 CN CN202210143608.4A patent/CN114559579A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1997510A (en) * | 2004-02-26 | 2007-07-11 | 先进能源科技公司 | Treatment of flexible graphite material and method thereof |
| US20080220154A1 (en) * | 2007-03-06 | 2008-09-11 | Gallagher Emerson R | Method of forming fluid flow field plates for electrochemical devices |
| CN112310426A (en) * | 2020-10-10 | 2021-02-02 | 滨州双峰石墨密封材料有限公司 | Preparation method of graphite bipolar plate and graphite bipolar plate prepared by preparation method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115954496A (en) * | 2022-08-31 | 2023-04-11 | 江苏金亚隆科技有限公司 | Flexible graphite bipolar plate |
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