CA1181127A - Process for preparing a fuel cell electrode substrate - Google Patents
Process for preparing a fuel cell electrode substrateInfo
- Publication number
- CA1181127A CA1181127A CA000418494A CA418494A CA1181127A CA 1181127 A CA1181127 A CA 1181127A CA 000418494 A CA000418494 A CA 000418494A CA 418494 A CA418494 A CA 418494A CA 1181127 A CA1181127 A CA 1181127A
- Authority
- CA
- Canada
- Prior art keywords
- binder
- weight
- carbon fiber
- electrode substrate
- fuel cell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/96—Carbon-based electrodes
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
- C04B35/80—Fibres, filaments, whiskers, platelets, or the like
- C04B35/83—Carbon fibres in a carbon matrix
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
Abstract:
An electrode substrate for a fuel cell having a high porosity, a good mechanical strength and electroconduc-tivity and a sharp distribution of pore radii is prepared by a process comprising mixing 30 to 50 % by weight of carbon fiber, 20 to 50 % by weight of a binder and 20 to 50 % by weight of organic granules, press-shaping the resultant mixture, curing the shaped product and calcining the cured product.
An electrode substrate for a fuel cell having a high porosity, a good mechanical strength and electroconduc-tivity and a sharp distribution of pore radii is prepared by a process comprising mixing 30 to 50 % by weight of carbon fiber, 20 to 50 % by weight of a binder and 20 to 50 % by weight of organic granules, press-shaping the resultant mixture, curing the shaped product and calcining the cured product.
Description
Process for preparin~ a fuel cell electrode substrate The present invention relates to a process for preparing a carbon fiber fuel cell electrode substrate as well as a product obtained by the process. More partic-ularly, it relates to a process for preparing an electrode 5 substrate for a fuel cell which has high porosity, good mechanical strength and electroconductivity, and a sharp distribution of pore radii, as well as a product prepared by the process.
A porous shaped article made from carbon fiber has attract~d attention recently, in particular, for use as a filter material and a fuel cell electrode substrate.
Particularly in the latter field, a porous carbonaceous article which has an excellent conductivity, chemical stability and mechanical strength, a high porosity and a sharp distribution of pore radii has been required.
Hitherto, 2 substrate for an electrode in a fuel cell has been prepared by the following processes:
1) One of the processes comprises coating a web of carbon fiber with thermally decomposed carbon by a chemical vacuwm evaporation as described in U.S. Patent No. 3,829,3~7. However, this process is not economical due to an expensive vacuum evaporation step and the mechanical strength of the product is reduced when the porosity thereof is increased, although the carbon fiber paper obtained by the process is excellent in chemical stability, permeability to gas and electroconductivity.
A porous shaped article made from carbon fiber has attract~d attention recently, in particular, for use as a filter material and a fuel cell electrode substrate.
Particularly in the latter field, a porous carbonaceous article which has an excellent conductivity, chemical stability and mechanical strength, a high porosity and a sharp distribution of pore radii has been required.
Hitherto, 2 substrate for an electrode in a fuel cell has been prepared by the following processes:
1) One of the processes comprises coating a web of carbon fiber with thermally decomposed carbon by a chemical vacuwm evaporation as described in U.S. Patent No. 3,829,3~7. However, this process is not economical due to an expensive vacuum evaporation step and the mechanical strength of the product is reduced when the porosity thereof is increased, although the carbon fiber paper obtained by the process is excellent in chemical stability, permeability to gas and electroconductivity.
2) Another method comprises carbonizing a mat of ~k pitch fiber in a non-oxidizing atmosphere, the mat of pitch fiber being obtained by using as a prelirninary binder an alcohol having a boiling point of at least 150C
as described in U.S. Patent No. 3,991,169. However, the S obtained product is defective in mechanical strength, although the porous sheet-like article obtained in this method has a high porosity and a good conductivity.
as described in U.S. Patent No. 3,991,169. However, the S obtained product is defective in mechanical strength, although the porous sheet-like article obtained in this method has a high porosity and a good conductivity.
3) A still another process comprises infusibilizing and carbonizing a web of pitch fiber produced by blow spinning to obtain a carbon fibrous web as described in U.S. Patent No. 3,960,601. The mechanical strength of the product obtained by the process is low~red when its porosity is to be high, although its conductivity is high.
Furthermore, these processes have a common disadvantage that it is difficult to control the distribution of pore radii. Therefore, when a carbonaceous article obtained is used as an electrode substrate in a fuel cell, the gas diffuses unevenly at the surface of the electrode sub-strate, resulting in a decrease of generating efficiency.
The electrode substrate prepared by one of the processes mentioned above is piled on a bipolar separator, and a~-cordingly, it has been difficult to reduce cost of manufacturing a fuel cell.
Recently, an electrode substrate with rib has been proposed instead of the bipolar separator-type substrate as in U.S. Patent No. 4,165,349, and accordingly, an electrode substrate which is less expensive and has improved electric~ mechanical and structural properties has been studied.
It is an object of the invention to provide a fuel cell electrode substrate which has a high porosity, a sharper distribution of pore radii than the conventional one and an excellent electroconducitivity and mechanical strength.
The process of the invention comprises mixing 30 to ~0 % by weight of carbon fiber, 20 to 50 % by weight of a binder and 20 to 50 % by weight of organic granules, press-shaping the resultant mixture, curing the shaped product and calcining the cur~d product.
The carbon fiber in the invention is short carbonaceous fiber having a fiber diameter in the range of 5 to 30 ~ and a fiber length in the range o 0.05 to 2 mm. With carbon fiber having a length of more than 2 mm, fibers tangle with one another to form a wool-pill during processing and the desired porosity and desired sharp distribution of pore radii are not obtained. The required strength of the product is not obtained with carbon fiber having a length of less than 0.05 mm.
The linear carbonizing shrinkage of the carbon fiber is in the range of 0.1 to 3.0 % when the carbon fiber is calcined u~ to 2000C. With a larger shrinkage, cracks may occur in the product on calcining. With such carbon fibers, a larger electrode substrate for fuel cell may be prepared according to the present invention.
The amount of the carbon fiber to be mixed in the invention is preferably in the range of 30 to 50 % by weight.
The binder in the invention is used for binding carbon fibers as a carbonaceous binder after carbonizing treat-ment. A resin having a carbonizing yield in the range of 30 to 75 % by weight is preferable for obtaining the desired porosity, for example, a phenol resin, pitch, a furfuryl alcohol resin, and the like, or a mixture thereof may be also used. Powdery phenol resin itself or a mix-ture of powdery phenol resin and powdery pitch is most preferable for dry blending, and an electrode substrate having excellent properties may be obtained with such a binder.
The amount of the binder to be mixed is preferably in the range of 20 to 50 ~ by weight. With less than 20 ~
by weight of the binder, the mechanical strength of the resulting substrate is low due to insufficient binder. On the other hand, the desired porosity and pore radii is not
Furthermore, these processes have a common disadvantage that it is difficult to control the distribution of pore radii. Therefore, when a carbonaceous article obtained is used as an electrode substrate in a fuel cell, the gas diffuses unevenly at the surface of the electrode sub-strate, resulting in a decrease of generating efficiency.
The electrode substrate prepared by one of the processes mentioned above is piled on a bipolar separator, and a~-cordingly, it has been difficult to reduce cost of manufacturing a fuel cell.
Recently, an electrode substrate with rib has been proposed instead of the bipolar separator-type substrate as in U.S. Patent No. 4,165,349, and accordingly, an electrode substrate which is less expensive and has improved electric~ mechanical and structural properties has been studied.
It is an object of the invention to provide a fuel cell electrode substrate which has a high porosity, a sharper distribution of pore radii than the conventional one and an excellent electroconducitivity and mechanical strength.
The process of the invention comprises mixing 30 to ~0 % by weight of carbon fiber, 20 to 50 % by weight of a binder and 20 to 50 % by weight of organic granules, press-shaping the resultant mixture, curing the shaped product and calcining the cur~d product.
The carbon fiber in the invention is short carbonaceous fiber having a fiber diameter in the range of 5 to 30 ~ and a fiber length in the range o 0.05 to 2 mm. With carbon fiber having a length of more than 2 mm, fibers tangle with one another to form a wool-pill during processing and the desired porosity and desired sharp distribution of pore radii are not obtained. The required strength of the product is not obtained with carbon fiber having a length of less than 0.05 mm.
The linear carbonizing shrinkage of the carbon fiber is in the range of 0.1 to 3.0 % when the carbon fiber is calcined u~ to 2000C. With a larger shrinkage, cracks may occur in the product on calcining. With such carbon fibers, a larger electrode substrate for fuel cell may be prepared according to the present invention.
The amount of the carbon fiber to be mixed in the invention is preferably in the range of 30 to 50 % by weight.
The binder in the invention is used for binding carbon fibers as a carbonaceous binder after carbonizing treat-ment. A resin having a carbonizing yield in the range of 30 to 75 % by weight is preferable for obtaining the desired porosity, for example, a phenol resin, pitch, a furfuryl alcohol resin, and the like, or a mixture thereof may be also used. Powdery phenol resin itself or a mix-ture of powdery phenol resin and powdery pitch is most preferable for dry blending, and an electrode substrate having excellent properties may be obtained with such a binder.
The amount of the binder to be mixed is preferably in the range of 20 to 50 ~ by weight. With less than 20 ~
by weight of the binder, the mechanical strength of the resulting substrate is low due to insufficient binder. On the other hand, the desired porosity and pore radii is not
- 4 --obtained with more than 50 ~ by weight of the binder.
The organic granules are used for controlling the production of pores in the inven~ion. Organic granules having a diameter in the range of 30 to 300 ~ are prefer-ably used in order to regulate the porosity and pore radius. On the other hand, organic granules used in the invention do not evaporate nor melt nor flow at 100~C.
That is, the organic granules may thermally deform but do not evaporate nor melt nor flow at the temperature and the pressure of shaping. ~n example of the preferred organic granules is polyvinyl alcohol, polyvinyl chloride, poly-ethylene, poly~ropylene, polystyrene or a mixture thereof.
The carbonizing yield of the organic granules is 30 % by weight or less. With organic granules having a carboniz-ing yield of more than 30 ~ by weight, it is difficult to control the porosity and/or pore radius.
The amount of organic granules to be mixed is prefer-ably in the range of 20 to 50 ~ by weight according to the desired porosity and pore radii of the electrode substrate.
The relative amounts of the carbon fiber, the binder and the organic granules is preferably selected so that the weight ratio of the total amount of the carbon fiber and the organic granules to the amount of the binder falls in the range of 1.5 to 4Ø Without this range it is not possible to obtain a product which satisfies all require-ments on the porosity, the bending strength, the perme-ability to gas and the bulk resistance.
The process of the invention is described in more detail hereinafter~
The predetermined amounts of short carbon fiber cut into the length of 0.05 to 2 mm, a binder and organic granules having the predetermined size are introduced into a mixing machine, stirred and blended homogeneously, preferably at a temperature of at most 60C since the binder may harden at higher temperature. Any conventional blender provided with blades may be used as the mixing machine.
~ he obtained uniform mixture is ~hen press-shaped by a mold press or a continuous press with roller, the tempera-ture and the pressure of pressing being suitably predeter-mined according to the size, thickness and form of a desired electrode substrate. When the temperature is too low, the hardening period of the binder is longer and it is unfavorable from the view point of productivity. When the pressure is too low, the carbon fibers are bound by the binder at least partially insufficiently and laminar cracks may be caused in the product. Usually, the press-shaping is carr~ed out at a temperature in the range of 100 to 2G0C under a pressure in the range of 5 to 100 kg/cm2 for 2 to 60 minutes.
The shaped product is then cured at about 150~C under about 0.5 kg/cm2 for 0.5 to 10 hours per l mm o thick-ness of the shaped product~
The cured product is then placed between graphite sheets under compression and then calcined and carbonized at a temperature in the range of 1000 to 3000C for 0.5 to
The organic granules are used for controlling the production of pores in the inven~ion. Organic granules having a diameter in the range of 30 to 300 ~ are prefer-ably used in order to regulate the porosity and pore radius. On the other hand, organic granules used in the invention do not evaporate nor melt nor flow at 100~C.
That is, the organic granules may thermally deform but do not evaporate nor melt nor flow at the temperature and the pressure of shaping. ~n example of the preferred organic granules is polyvinyl alcohol, polyvinyl chloride, poly-ethylene, poly~ropylene, polystyrene or a mixture thereof.
The carbonizing yield of the organic granules is 30 % by weight or less. With organic granules having a carboniz-ing yield of more than 30 ~ by weight, it is difficult to control the porosity and/or pore radius.
The amount of organic granules to be mixed is prefer-ably in the range of 20 to 50 ~ by weight according to the desired porosity and pore radii of the electrode substrate.
The relative amounts of the carbon fiber, the binder and the organic granules is preferably selected so that the weight ratio of the total amount of the carbon fiber and the organic granules to the amount of the binder falls in the range of 1.5 to 4Ø Without this range it is not possible to obtain a product which satisfies all require-ments on the porosity, the bending strength, the perme-ability to gas and the bulk resistance.
The process of the invention is described in more detail hereinafter~
The predetermined amounts of short carbon fiber cut into the length of 0.05 to 2 mm, a binder and organic granules having the predetermined size are introduced into a mixing machine, stirred and blended homogeneously, preferably at a temperature of at most 60C since the binder may harden at higher temperature. Any conventional blender provided with blades may be used as the mixing machine.
~ he obtained uniform mixture is ~hen press-shaped by a mold press or a continuous press with roller, the tempera-ture and the pressure of pressing being suitably predeter-mined according to the size, thickness and form of a desired electrode substrate. When the temperature is too low, the hardening period of the binder is longer and it is unfavorable from the view point of productivity. When the pressure is too low, the carbon fibers are bound by the binder at least partially insufficiently and laminar cracks may be caused in the product. Usually, the press-shaping is carr~ed out at a temperature in the range of 100 to 2G0C under a pressure in the range of 5 to 100 kg/cm2 for 2 to 60 minutes.
The shaped product is then cured at about 150~C under about 0.5 kg/cm2 for 0.5 to 10 hours per l mm o thick-ness of the shaped product~
The cured product is then placed between graphite sheets under compression and then calcined and carbonized at a temperature in the range of 1000 to 3000C for 0.5 to
5 hours in a calcining oven under an inert atmosphere to obtain a desired electrode substrate.
One of the specific features of the process of the inven-tion lies in the easiness of preparing of an electrode sub-strate of any desired size from a small one to a large onel for instance, of a si~e of 1000 mm in length and width and 3 mm in thickness, and accordingly, the industrial effective-ness of the invention is highly evaluated.
The product obtained by the process of the invention has excellent properties, for example, a high porosity of 40 to 85 %, a mechanical strength such as a bending strength of 80 kg/cm2 or more, a permeability to gas of 100 to 1000 ml/cm2.hr.mmOAq. and a bulk resistance of 5 x 10 2Q.cm or less.
The electrode substrate of the invention has open pores and the porosity thereof is in the range of 40 to 85 %.
In a substrate having a porosity of less than 40 %, the pressure loss of hydrogen or oxygen gas is high in the
One of the specific features of the process of the inven-tion lies in the easiness of preparing of an electrode sub-strate of any desired size from a small one to a large onel for instance, of a si~e of 1000 mm in length and width and 3 mm in thickness, and accordingly, the industrial effective-ness of the invention is highly evaluated.
The product obtained by the process of the invention has excellent properties, for example, a high porosity of 40 to 85 %, a mechanical strength such as a bending strength of 80 kg/cm2 or more, a permeability to gas of 100 to 1000 ml/cm2.hr.mmOAq. and a bulk resistance of 5 x 10 2Q.cm or less.
The electrode substrate of the invention has open pores and the porosity thereof is in the range of 40 to 85 %.
In a substrate having a porosity of less than 40 %, the pressure loss of hydrogen or oxygen gas is high in the
- 6 ~
course of diffusion of gas through the substrate, and accordingly, the distribution of gases reached at ~he surface of the electrode becomes uneven resulting in a decrease oE
generating efficiency. A substrate having a porosity of more than 85 ~ is too weak in mechanical strength to be used as an electrode substrate.
The electrode substrate of the invention has a bending strength in the range of 30 kg/cm2 or more. An electrode substrate having a bending strength of less than 80 kg/cm2 is fragile and is apt to be broken while being processed into an electrode. The typical procedure for this is surface-impregnating with a catalyst, coating with a polytetrafluoro-ethylene layer and constructing the fuel cell, as taught in U. S. Patent No. 3,960,601.
The electrode substrate of the invention has a perme-ability to gas, hydrogen or oxygen, in the range of 100 to 1000 ml/cm~.hr.mm.Aq. If the gas permeability is less than 100 ml/cm2Ohr.mm.Aq., the pressure loss is high in the course of difusion of hydrogen or oxygen gas through the substrate, resulting in the uneven distribution of gas at the surface of the electrode. When the gas permeability is more than 1000 ml/cm .hr.mm.Aq., the substrate has large pores, resulting in the decrease of mechanical strength and the uneven distribution of gas supply at the surface of the electrode.
The electrode substrate of the invention has a bulk resistance in the range of 5 x 10 2Q.Cm or less. If the bulk resistance in the direction of th;ckness is more than 5 x 10 2Q.cm the electric resistance of the substrate is high and generating efficiency is reduced.
The pore radii are required to be in the range of 10 to 30 ~ for a fuel cell electrode substrate. According to the invention, about 70 % or more pores of the electrode substrate obtained by the process of the invention have a radius in the range of 5 to 30 ~.
The invention is described in more detail while referring to the following non-limiting example.
~ 7 EXAMPLE
Carbon fiber obtained from pitch having diameter of 12 to 16 ~ and lengch of 0.1 to 0.6 mm, a granular binder having granule diameters of at most 100 ~and organic granules of which at least 70 % by wei~ht have diameter of 30 to 100 ~ were uniformly blended at room temperature in a blender provided with blades~ The compositions of three components are shown in Table 1. In Table 1 are also shown the shrinkage of the carbon fiber and the kinds of binder and organic granules used.
Table 1 Carbon Fiber Binder Organic Granule No. Wt % Shrinkag~% Wt % Kind Wt % Xind 1 40 1.7 30Phenol Resin1) 30 PVA3) 2 30 1.7 30Phenol Resin 40 PVA
3 40 1.7 35Phenol Resin 25 PVA
4 40 1.2 30Phenol Resin 30 PVA
1.7 30Mixture2) 30 PVA
6 40 1.7 30Phenol Resin 30 PVC
course of diffusion of gas through the substrate, and accordingly, the distribution of gases reached at ~he surface of the electrode becomes uneven resulting in a decrease oE
generating efficiency. A substrate having a porosity of more than 85 ~ is too weak in mechanical strength to be used as an electrode substrate.
The electrode substrate of the invention has a bending strength in the range of 30 kg/cm2 or more. An electrode substrate having a bending strength of less than 80 kg/cm2 is fragile and is apt to be broken while being processed into an electrode. The typical procedure for this is surface-impregnating with a catalyst, coating with a polytetrafluoro-ethylene layer and constructing the fuel cell, as taught in U. S. Patent No. 3,960,601.
The electrode substrate of the invention has a perme-ability to gas, hydrogen or oxygen, in the range of 100 to 1000 ml/cm~.hr.mm.Aq. If the gas permeability is less than 100 ml/cm2Ohr.mm.Aq., the pressure loss is high in the course of difusion of hydrogen or oxygen gas through the substrate, resulting in the uneven distribution of gas at the surface of the electrode. When the gas permeability is more than 1000 ml/cm .hr.mm.Aq., the substrate has large pores, resulting in the decrease of mechanical strength and the uneven distribution of gas supply at the surface of the electrode.
The electrode substrate of the invention has a bulk resistance in the range of 5 x 10 2Q.Cm or less. If the bulk resistance in the direction of th;ckness is more than 5 x 10 2Q.cm the electric resistance of the substrate is high and generating efficiency is reduced.
The pore radii are required to be in the range of 10 to 30 ~ for a fuel cell electrode substrate. According to the invention, about 70 % or more pores of the electrode substrate obtained by the process of the invention have a radius in the range of 5 to 30 ~.
The invention is described in more detail while referring to the following non-limiting example.
~ 7 EXAMPLE
Carbon fiber obtained from pitch having diameter of 12 to 16 ~ and lengch of 0.1 to 0.6 mm, a granular binder having granule diameters of at most 100 ~and organic granules of which at least 70 % by wei~ht have diameter of 30 to 100 ~ were uniformly blended at room temperature in a blender provided with blades~ The compositions of three components are shown in Table 1. In Table 1 are also shown the shrinkage of the carbon fiber and the kinds of binder and organic granules used.
Table 1 Carbon Fiber Binder Organic Granule No. Wt % Shrinkag~% Wt % Kind Wt % Xind 1 40 1.7 30Phenol Resin1) 30 PVA3) 2 30 1.7 30Phenol Resin 40 PVA
3 40 1.7 35Phenol Resin 25 PVA
4 40 1.2 30Phenol Resin 30 PVA
1.7 30Mixture2) 30 PVA
6 40 1.7 30Phenol Resin 30 PVC
7 40 1.7 30Phenol Resin 30 P~
Note 1). Manufactured by Cashew Chem. Ind. Co., Japan, No. 5.
2). Composed by 35 % by weight of pitch and 65 % by weight of phenol resin (Note 1).
3). Manufactured by The Nippon Synthetic Chemical Industry Co., Ltd. Japan, P~250.
Note 1). Manufactured by Cashew Chem. Ind. Co., Japan, No. 5.
2). Composed by 35 % by weight of pitch and 65 % by weight of phenol resin (Note 1).
3). Manufactured by The Nippon Synthetic Chemical Industry Co., Ltd. Japan, P~250.
- 8 ~ 27 The linear shrinkage (%) of the carbon fiber was cal-culated by elevating the temperature of the fiher bundle up to 2000C at the rate of 750C per hour, maintaining the temperature for 30 minutes, allowing to cool and then measuring the length of the fiber bundle.
The carbonizing yield of the binder or the organic granule was measured by the method according to JIS-M-8802 and each carbonizing yield are as follows:
(1) Binder:
Phenol resin (Note 1 of Table 1); 48 %
Mixture ~Note 2 of Table 1); 59 %
(2) Organic Granule:
Polyvinyl alcohol (PVA~ Note 3 of Table 1); 0.9 %
Polypropylene, 0.8 PolyYinyl chloride (PVC); 5.6 Polyethylene (PE); 0.1 %
Polystyrene; 1.0 %
After blending the three components, the resulting mixture was introduced into a plate mold provided with a rib of dimensions lQ00 mm x 1000 mm and pressed at 130C, 75 kg/cm2 for 5 minutes. The shaped product of 3 mm in thickness was then cured at 0.5 kg/cm2 in an oven of 150C for 6 hours to harden completely the binder. The resulting product was placed between graphite sheets and calcinated at 2000C under inert atmosphere for 1 hour.
The physical properties of the obtained electrode substrate with rib are shown in Table 2.
As seen from T~ble 2, the electrode substrates of the invention show excellent physical properties as a fuel cell electrode substrate. Furthermore, no cracks occurred in the substrate even on calcining at 2000C.
The carbonizing yield of the binder or the organic granule was measured by the method according to JIS-M-8802 and each carbonizing yield are as follows:
(1) Binder:
Phenol resin (Note 1 of Table 1); 48 %
Mixture ~Note 2 of Table 1); 59 %
(2) Organic Granule:
Polyvinyl alcohol (PVA~ Note 3 of Table 1); 0.9 %
Polypropylene, 0.8 PolyYinyl chloride (PVC); 5.6 Polyethylene (PE); 0.1 %
Polystyrene; 1.0 %
After blending the three components, the resulting mixture was introduced into a plate mold provided with a rib of dimensions lQ00 mm x 1000 mm and pressed at 130C, 75 kg/cm2 for 5 minutes. The shaped product of 3 mm in thickness was then cured at 0.5 kg/cm2 in an oven of 150C for 6 hours to harden completely the binder. The resulting product was placed between graphite sheets and calcinated at 2000C under inert atmosphere for 1 hour.
The physical properties of the obtained electrode substrate with rib are shown in Table 2.
As seen from T~ble 2, the electrode substrates of the invention show excellent physical properties as a fuel cell electrode substrate. Furthermore, no cracks occurred in the substrate even on calcining at 2000C.
- 9 Table 2 Porosity Bending Gas Permeability Bulk Strenath Resistance _o~ Vol. % kg/cm ml/cm2 hr.mm.Aq. Q .cm 1 ~7 165 130 2.~ x 10 2 2 70 130 240 3.~ x 10 3 60 180 105 2.1 x 10 2 4 68 150 145 3.3 x 10 58 195 101 2.5 x 10 2 ~6 176 398 2.3 x 10 7 6~ 15~ 980 2,~ ~ 10 2 In Table 2, the physical properties were measured as follows:
(a) Porosity (Vol. %):
The porosities were measured in accordance with the 3apanese Industrial Standard JIS-Z-2056 (1976).
(~) Ber.ding Strength (kg/cm2):
The bendinq strengths were measured on samples of size 100 mm in length and width and 2.5 mm in thicknPss in accordance with JIS-K-6911.
~c~ Gas Permeability ~ml/cm2.hr.mmAq.):
Both ends of each cylindrical sample substrate were put between two hollow cylindrical tubes, and a predeter-mined amount of air flow was supplied from one end of the sample to the another end which was open to the atmosphere to meAsure the pressure loss between two ends of the sample. The gas permeabilities Qs were determined from the following equation:
(a) Porosity (Vol. %):
The porosities were measured in accordance with the 3apanese Industrial Standard JIS-Z-2056 (1976).
(~) Ber.ding Strength (kg/cm2):
The bendinq strengths were measured on samples of size 100 mm in length and width and 2.5 mm in thicknPss in accordance with JIS-K-6911.
~c~ Gas Permeability ~ml/cm2.hr.mmAq.):
Both ends of each cylindrical sample substrate were put between two hollow cylindrical tubes, and a predeter-mined amount of air flow was supplied from one end of the sample to the another end which was open to the atmosphere to meAsure the pressure loss between two ends of the sample. The gas permeabilities Qs were determined from the following equation:
10 x 60 x 103 ~ 50.24 x ~p (ml/cm2.hr.mmAq) wherein ~p is the measured pressure loss ~mmA~.), 50.24 represents the measured area, i.e. a circle of 80 mm in - 9a -diameter, and 10 (l/min.) is the predetermined amoun~ of air flow.
(d) Bulk Resistance (Q.cm):
In accordance with SRIS ~Standards of the Japan Rubber Association) 2301-1969, both ends of each sample subs~rate were ooated with an electroconductive coating material to measure the electrical resistance between two ends of the sample. The bulk resistances Pv (Q.cm) were calculated from the measured electrical resistances R (~) by the following equation:
Pv = R . w . t/Q
wherein Q is the lonyitudinal length (cm~ between two ends of the sample (in the measured direction~ and w and t are the length and width, both in cm, respectively, defining the cross section of the sample.
(d) Bulk Resistance (Q.cm):
In accordance with SRIS ~Standards of the Japan Rubber Association) 2301-1969, both ends of each sample subs~rate were ooated with an electroconductive coating material to measure the electrical resistance between two ends of the sample. The bulk resistances Pv (Q.cm) were calculated from the measured electrical resistances R (~) by the following equation:
Pv = R . w . t/Q
wherein Q is the lonyitudinal length (cm~ between two ends of the sample (in the measured direction~ and w and t are the length and width, both in cm, respectively, defining the cross section of the sample.
Claims (13)
1. A process for preparing a fuel cell electrode substrate, comprising mixing 30 to 50 % by weight of carbon fiber which has a diameter of 5 to 30 µ, a length of 0.05 to 2 mm and a linear carbonizing shrinkage on calcining at 2000°C of 0.1 to 3.0 %, 20 to 50 % by weight of a binder and 20 to 50 % by weight of organic granules, press-shaping the resultant mixture, curing the shaped product and calcining the cured product.
2. The process of claim 1, wherein the binder has a carbonizing yield of 30 to 75 % by weight.
3. The process of claim 2, wherein the binder is selected from the group consisting of a phenol resin, pitch, a furfuryl alcohol resin and a mixture thereof.
4. The process of claim 3, wherein the binder is a phenol resin or a mixture of a phenol resin and pitch.
5. The process of claim 1, wherein the organic granule has a carbonizing yield of at most 30 % by weight and a diameter of 30 to 300 µ.
6. The process of claim 5, wherein the organic granule does not evaporate nor melt nor flow at 100°C.
7. The process of claim 5 or 6, wherein the organic granule is selected from the group consisting of polyvinyl alcohol, polyvinyl chloride, polyethylene, polypropylene, polystyrene and a mixture thereof.
8. The process of claim 1 or 2 wherein the weight ratio of the total amount of the carbon fiber and the organic granules to the amount of the binder is 1.5 to 4Ø
9. The process of claim 1 or 2 wherein the mixture of carbon fiber, the binder and the organic granules is press-shaped at a temperature of 100 to 200°C under a pressure of 5 to 100 kg/cm2 for 2 to 60 minutes.
10. The process of claim 1 or 2 wherein the shaped product is cured at about 150°C under about 0.5 kg/cm2 for 0.5 to 10 hours per 1 mm in thickness of the shaped product.
11. The process of claim 1 or 2, wherein the cured product is calcinated at a temperature of 1000 to 3000°C
under an inert atmosphere for 0.5 to 5 hours.
under an inert atmosphere for 0.5 to 5 hours.
12. A fuel cell electrode substrate based on carbon fiber having a porosity of 40 to 85 %, a bending strength of at least 80 kg/cm2, a gas permeability of 100 to 1000 ml/
cm2.hr.mm.Aq. and a bulk resistance of at most 5 x 10-2 .OMEGA..cm.
cm2.hr.mm.Aq. and a bulk resistance of at most 5 x 10-2 .OMEGA..cm.
13. The substrate of claim 12, of which at least 70 % of pores have a radius of 5 to 30µ.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP214258/81 | 1981-12-29 | ||
| JP56214258A JPS58117649A (en) | 1981-12-29 | 1981-12-29 | Manufacture of electrode substrate of fuel cell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1181127A true CA1181127A (en) | 1985-01-15 |
Family
ID=16652767
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000418494A Expired CA1181127A (en) | 1981-12-29 | 1982-12-23 | Process for preparing a fuel cell electrode substrate |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4506028A (en) |
| JP (1) | JPS58117649A (en) |
| CA (1) | CA1181127A (en) |
| DE (1) | DE3247799C2 (en) |
| FR (1) | FR2519192B1 (en) |
| GB (1) | GB2117746B (en) |
Families Citing this family (55)
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|---|---|---|---|---|
| JPS5937662A (en) * | 1982-08-24 | 1984-03-01 | Kureha Chem Ind Co Ltd | Electrode substrate for monopolar type fuel cell with two-layer structure |
| JPS5946763A (en) * | 1982-09-10 | 1984-03-16 | Kureha Chem Ind Co Ltd | Two-layered electrode base plate for monopolar fuel cell |
| GB2128395B (en) * | 1982-10-01 | 1986-01-08 | Kureha Chemical Ind Co Ltd | Fuel cell electrode substrate having elongated holes for feeding reactant gases |
| JPS6059663A (en) * | 1983-09-12 | 1985-04-06 | Hitachi Ltd | Electrode plate for fuel cell and its manufacture |
| GR81142B (en) * | 1983-12-05 | 1985-04-04 | Dow Chemical Co | Secondary electrical energy storage device and electrode therefor |
| JPS60150559A (en) * | 1984-01-18 | 1985-08-08 | Showa Denko Kk | Carbon thin plate for fuel battery and method for manufacturing the same |
| JPS60236461A (en) * | 1984-04-04 | 1985-11-25 | Kureha Chem Ind Co Ltd | Electrode substrate for fuel cell and its manufacture |
| CA1259101A (en) * | 1984-04-09 | 1989-09-05 | Hiroyuki Fukuda | Carbonaceous fuel cell electrode substrate incorporating three-layer separator, and process for preparation thereof |
| US4794043A (en) * | 1985-04-30 | 1988-12-27 | Kureha Kagaku Kogyo Kabushiki Kaisha | Carbon product comprising carbonaceous materials joined together, said carbon product for electrode substrate of fuel cells and process for production thereof |
| JPS6246909A (en) * | 1985-08-23 | 1987-02-28 | Kureha Chem Ind Co Ltd | Production of carbonaceous sheet |
| US4818640A (en) * | 1985-09-25 | 1989-04-04 | Kureha Kagaku Kogyo Kabushiki Kaisha | Carbonaceous composite product produced by joining carbonaceous materials together by tetrafluoroethylene resin, and process for producing the same |
| JPS6282663A (en) * | 1985-10-04 | 1987-04-16 | Kureha Chem Ind Co Ltd | Electrode substrate for manifold mounted fuel cell and its manufacture |
| JPS62110262A (en) * | 1985-10-25 | 1987-05-21 | Kureha Chem Ind Co Ltd | Electrode substrate for fuel cell with end sealing member and its manufacture |
| JPS62123662A (en) * | 1985-11-25 | 1987-06-04 | Kureha Chem Ind Co Ltd | Electrode substrate for fuel cell |
| JPS62295926A (en) * | 1986-06-16 | 1987-12-23 | Nitto Boseki Co Ltd | Preparation of chopped carbon fiber strand |
| JPH07118323B2 (en) * | 1986-07-14 | 1995-12-18 | 呉羽化学工業株式会社 | Method for manufacturing electrode substrate |
| US4818741A (en) * | 1986-11-20 | 1989-04-04 | Electric Power Research Institute, Inc. | Porous and porous-nonporous composites for battery electrodes |
| US4920017A (en) * | 1986-11-20 | 1990-04-24 | Electric Power Research Institute, Inc. | Porous and porous-nonporous composites for battery electrodes |
| JPS63254669A (en) * | 1987-04-10 | 1988-10-21 | Toray Ind Inc | Electrode substrate for fuel cell |
| US4810594A (en) * | 1987-05-14 | 1989-03-07 | International Fuel Cells Corporation | Fuel cell electrode and method of making and using same |
| US4898631A (en) * | 1988-01-15 | 1990-02-06 | California Institute Of Technology | Method for fabricating ceramic filaments and high density tape casting method |
| US5057362A (en) * | 1988-02-01 | 1991-10-15 | California Institute Of Technology | Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells |
| US4957673A (en) * | 1988-02-01 | 1990-09-18 | California Institute Of Technology | Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells and method for fabrication thereof |
| US4913706A (en) * | 1988-09-19 | 1990-04-03 | International Fuel Cells Corporation | Method for making a seal structure for an electrochemical cell assembly |
| JPH02106876A (en) * | 1988-10-14 | 1990-04-18 | Kureha Chem Ind Co Ltd | Manufacture of porous carbon electrode base for fuel cell |
| US5080963A (en) * | 1989-05-24 | 1992-01-14 | Auburn University | Mixed fiber composite structures high surface area-high conductivity mixtures |
| US5096560A (en) * | 1989-05-30 | 1992-03-17 | Mitsubishi Petrochemical Co., Ltd. | Electrode for electrochemical detectors |
| US5238672A (en) * | 1989-06-20 | 1993-08-24 | Ashland Oil, Inc. | Mesophase pitches, carbon fiber precursors, and carbonized fibers |
| WO1991006131A1 (en) * | 1989-10-17 | 1991-05-02 | Kureha Kagaku Kogyo Kabushiki Kaisha | Porous carbon material equipped with flat sheet-like ribs and production method thereof |
| EP0651452A1 (en) * | 1993-11-01 | 1995-05-03 | Osaka Gas Co., Ltd. | Porous carbonaceous material and a method for producing the same |
| US5525423A (en) * | 1994-06-06 | 1996-06-11 | Memtec America Corporation | Method of making multiple diameter metallic tow material |
| US5584109A (en) * | 1994-06-22 | 1996-12-17 | Memtec America Corp. | Method of making a battery plate |
| WO1996012313A1 (en) * | 1994-10-12 | 1996-04-25 | Bipolar Technologies Corporation | Bipolar battery cells, batteries, and methods |
| US5582937A (en) * | 1994-10-12 | 1996-12-10 | Bipolar Technologies, Inc. | Bipolar battery cells, batteries and methods |
| US5556627A (en) * | 1994-10-12 | 1996-09-17 | Bipolar Technologies, Inc. | Bipolar battery cells, batteries and methods |
| US5582622A (en) * | 1994-10-12 | 1996-12-10 | Bipolar Technologies, Inc. | Methods of making bipolar battery plates comprising carbon and a fluoroelastomer |
| US5726105A (en) * | 1995-04-20 | 1998-03-10 | International Fuel Cells | Composite article |
| US5776633A (en) * | 1995-06-22 | 1998-07-07 | Johnson Controls Technology Company | Carbon/carbon composite materials and use thereof in electrochemical cells |
| US5863673A (en) * | 1995-12-18 | 1999-01-26 | Ballard Power Systems Inc. | Porous electrode substrate for an electrochemical fuel cell |
| US6090477A (en) * | 1998-09-11 | 2000-07-18 | Ut-Battelle, Llc | Gas storage carbon with enhanced thermal conductivity |
| US20020180088A1 (en) * | 2001-04-03 | 2002-12-05 | Mitsubishi Chemical Corporation | Process for producing separator for fuel cell |
| US6916574B2 (en) * | 2002-07-09 | 2005-07-12 | Plastics Engineering Company | Method for forming a fuel cell electrode using a resole binder |
| DE10232129A1 (en) * | 2002-07-11 | 2004-02-05 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Fluid distribution device and method for manufacturing a fluid distribution device |
| JP5168451B2 (en) * | 2007-03-13 | 2013-03-21 | 独立行政法人 宇宙航空研究開発機構 | Method for producing porous molded body and method for producing porous filled molded body |
| DE102008004005A1 (en) * | 2008-01-11 | 2009-07-16 | CeTech Co., Ltd., Tanzih | Process to make fuel cell gas diffusion cell by hydro-interlacing carbon fiber matrix followed by further treatment stages |
| JP6181308B2 (en) * | 2013-12-09 | 2017-08-16 | アウディ アクチェンゲゼルシャフトＡｕｄｉ Ａｇ | Dry fuel cell precursor substrate and substrate manufacturing method |
| US10332693B2 (en) | 2016-07-15 | 2019-06-25 | Nanotek Instruments, Inc. | Humic acid-based supercapacitors |
| EP3490042B1 (en) * | 2016-07-22 | 2021-06-09 | Mitsubishi Chemical Corporation | Porous base material, porous electrode, carbon fiber paper, method for manufacturing carbon fiber paper, and method for manufacturing porous base material |
| US11254616B2 (en) | 2016-08-04 | 2022-02-22 | Global Graphene Group, Inc. | Method of producing integral 3D humic acid-carbon hybrid foam |
| US10731931B2 (en) | 2016-08-18 | 2020-08-04 | Global Graphene Group, Inc. | Highly oriented humic acid films and highly conducting graphitic films derived therefrom and devices containing same |
| US10597389B2 (en) | 2016-08-22 | 2020-03-24 | Global Graphene Group, Inc. | Humic acid-bonded metal foil film current collector and battery and supercapacitor containing same |
| US10014519B2 (en) | 2016-08-22 | 2018-07-03 | Nanotek Instruments, Inc. | Process for producing humic acid-bonded metal foil film current collector |
| US10593932B2 (en) | 2016-09-20 | 2020-03-17 | Global Graphene Group, Inc. | Process for metal-sulfur battery cathode containing humic acid-derived conductive foam |
| US10647595B2 (en) | 2016-08-30 | 2020-05-12 | Global Graphene Group, Inc. | Humic acid-derived conductive foams and devices |
| US20180061517A1 (en) * | 2016-08-30 | 2018-03-01 | Nanotek Instruments, Inc. | Highly Conductive Graphitic Films and Production Process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3407038A (en) * | 1962-07-09 | 1968-10-22 | Union Carbide Corp | Shredded carbonaceous fiber compactions and method of making the same |
| US3395049A (en) * | 1963-07-15 | 1968-07-30 | Exxon Research Engineering Co | Method of making a porous electrode |
| JPS4815150B1 (en) * | 1970-08-03 | 1973-05-12 | ||
| US3829327A (en) * | 1972-07-03 | 1974-08-13 | Kreha Corp | Carbon paper |
| JPS5318603B2 (en) * | 1973-07-10 | 1978-06-16 | ||
| JPS5817319B2 (en) * | 1974-03-13 | 1983-04-06 | 呉羽化学工業株式会社 | TAKOSHITSU CARBON SEAT NO SEIZOU HOU |
| US3960601A (en) * | 1974-09-27 | 1976-06-01 | Union Carbide Corporation | Fuel cell electrode |
| US4165349A (en) * | 1977-08-15 | 1979-08-21 | United Technologies Corporation | Method for fabricating a ribbed electrode substrate |
| US4269642A (en) * | 1979-10-29 | 1981-05-26 | United Technologies Corporation | Method of forming densified edge seals for fuel cell components |
| JPS57166354A (en) * | 1981-04-01 | 1982-10-13 | Kureha Chemical Ind Co Ltd | Porous carbon formed body and manufacture |
| US4426340A (en) * | 1981-09-29 | 1984-01-17 | United Technologies Corporation | Process for fabricating ribbed electrode substrates and other articles |
| US4374906A (en) * | 1981-09-29 | 1983-02-22 | United Technologies Corporation | Ribbed electrode substrates |
-
1981
- 1981-12-29 JP JP56214258A patent/JPS58117649A/en active Granted
-
1982
- 1982-12-17 US US06/450,802 patent/US4506028A/en not_active Expired - Lifetime
- 1982-12-23 CA CA000418494A patent/CA1181127A/en not_active Expired
- 1982-12-23 DE DE3247799A patent/DE3247799C2/en not_active Expired
- 1982-12-23 GB GB08236629A patent/GB2117746B/en not_active Expired
- 1982-12-28 FR FR8221891A patent/FR2519192B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2519192A1 (en) | 1983-07-01 |
| GB2117746B (en) | 1985-10-02 |
| GB2117746A (en) | 1983-10-19 |
| DE3247799C2 (en) | 1986-11-13 |
| JPH0136670B2 (en) | 1989-08-01 |
| FR2519192B1 (en) | 1987-02-27 |
| JPS58117649A (en) | 1983-07-13 |
| US4506028A (en) | 1985-03-19 |
| DE3247799A1 (en) | 1983-07-14 |
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