CA2235431C - Solid polymer type fuel cell and method for manufacturing the same - Google Patents
Solid polymer type fuel cell and method for manufacturing the same Download PDFInfo
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- CA2235431C CA2235431C CA002235431A CA2235431A CA2235431C CA 2235431 C CA2235431 C CA 2235431C CA 002235431 A CA002235431 A CA 002235431A CA 2235431 A CA2235431 A CA 2235431A CA 2235431 C CA2235431 C CA 2235431C
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- 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
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
- H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
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- 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
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
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- 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
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- 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
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- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49108—Electric battery cell making
- Y10T29/49115—Electric battery cell making including coating or impregnating
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Abstract
An electrode of solid polymer electrolyte fuel cells is produced by a step of preparing a mixed liquid containing an organic solvent, a noble metal catalyst-supporting carbon powder and a colloid of a solid polymer electrolyte having a particle size of 1 nm or more and less than 400 nm, said colloid being adsorbed to the carbon powder and a step of forming an electrode by coating said mixed liquid on one side of a gas-diffusible layer.
According to the present invention, the solid polymer electrolyte is surely adsorbed to the surface of the catalyst and thus a wide reaction area can be secured.
Furthermore, thickness of the solid polymer electrolyte layer can be controlled to one in which hydrogen and oxygen can be easily diffused.
According to the present invention, the solid polymer electrolyte is surely adsorbed to the surface of the catalyst and thus a wide reaction area can be secured.
Furthermore, thickness of the solid polymer electrolyte layer can be controlled to one in which hydrogen and oxygen can be easily diffused.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a method for manufacturing an assembly of a solid polymer electrolyte membrane and electrodes and to an assembly manufactured by the method, and more particularly to a fuel cell which is made using the assembly and uses as a fuel a reducing agent such as pure hydrogen, modified hydrogen obtained from methanol or fossil fuels or methanol and as an oxi-dizing agent air or o};ygen, especially a fuel cell which uses a solid polymer as an electrolyte.
1. Field of the Invention The present invention relates to a method for manufacturing an assembly of a solid polymer electrolyte membrane and electrodes and to an assembly manufactured by the method, and more particularly to a fuel cell which is made using the assembly and uses as a fuel a reducing agent such as pure hydrogen, modified hydrogen obtained from methanol or fossil fuels or methanol and as an oxi-dizing agent air or o};ygen, especially a fuel cell which uses a solid polymer as an electrolyte.
2. Description of the Related Art One of the most important factors which govern the discharge performance of solid polymer type fuel cells constructed using an assembly of a solid polymer electro-lyte membrane and electrodes is the reaction area at an interface of three phases formed by pores which are pas-sages for feeding reaction gas, a solid polymer electro-lyte having protonic conductivity due to containing of water, and an electrode material of electronic conductor at the interface between a solid polymer electrolyte membrane and an electrode.
Hitherto, in order to increase the three face interface, it has been attempted to apply a layer prepared by mixing and dispersing an electrode material and a solid polymer electrolyte to the interface between the membrane and a porous electrodES. For example, JP-B-62-61118 and JP-B-62-61119 disclose a method which comprises coating a mixture of a solution of solid polymer electrolyte with a catalyst compound on a solid polymer membrane, hot press-ing the coated membrane on an electrode material and then reducing the catalyst compound or carrying out the coating after the reduction and then carrying out the hot pressing.
JP-A-3-1842E>6 uses a powder prepared by coating a solid polymer electrolyte on the surface of a polymer resin, and JP-A-3-295'_72 employs a method which comprises incorporating a powder of a solid polymer electrolyte into an electrode. JP-A-5-36418 discloses a method which com-prises mixing a solid polymer electrolyte, a catalyst, a carbon powder and a f7_uoropolymer and forming the mixture into a film to form an electrode.
All of the above patent publications use alcohol solvents for the solutions of the solid polymer electro-lyte. Furthermore, U.S. Pat. No.5,211,984 reports a method which comprises preparing an inky dispersion comprising a solid polymer electrolyte, a catalyst and a carbon powder using glycerin or tetrabutylammonium salt as a solvent, casting the dispersion on a polytetrafluoroethylene (hereinafter referred to as "PTFE") film, and then trans-ferring it onto the surface of a solid polymer electrolyte membrane or a method which comprises changing the exchang-ing group of a solid polymer electrolyte membrane to Na type, coating the above inky dispersion on the surface of the membrane, and heating and drying the coat at 125°C or higher to again change the group to H type.
However, wh<~n a catalyst-supporting carbon powder and a water repellent material such as fluoropoly-mer or a carbon powder subjected to water repelling treat-ment are simultaneously added to the solid polymer elec-trolyte solution, much solid polymer electrolyte is adsorbed to the water repellent material or the carbon powder subjected to water repelling treatment, and accord-ingly the degree of contact between the solid polymer electrolyte and the catalyst becomes insufficient and non-uniform, and no sufficient reaction area can be ensured at the interface between the electrode and the ion-exchange membrane.
Moreover, in all of the above methods, it is difficult to coat the solid polymer electrolyte at a suit-able thickness on the surface of the catalyst, and in fact the thickness of coat of the polymer electrolyte cannot be controlled. Therefore, there are problems that the cata-lyst cannot be sufficiently coated on the polymer electro-lyte, resulting in a :mall reaction area or thickness of the coat is too large and diffusion route of hydrogen or oxygen becomes longer to cause increase of concentration over voltage.
Furthermore,. when the dispersion with an alco-holic solvent is coated on a porous substrate or when the inky dispersion is coated on a porous substrate, the dis-persion cannot be dirt=_ctly molded on the surface of the substrate as the dispersion penetrates or permeates into the inside of the substrate and thus, complicated process-ing techniques such as transferring are needed.
Moreover, the above-mentioned method of directly coating the inky dispfsrsion on the surface of the membrane requires complicated production technique of replacing the exchange group of the membrane many times.
"Journal of Electroanalytical Chemistry", 417 (1996) 105-111 mentions that the thinner thickness of polymer electrolyte 1<~yer on the catalyst surface gives the more easy occurrence of diffusion of hydrogen and oxy-gen, and according to FIG. 7, when the thickness is 400 nm, the highest characteristics are obtained. However, this is a result of experiment conducted on a smooth Pt surface, and does not concern with the thickness of the polymer electrolyte layer on the catalyst surface in the catalyst layer of porous electode.
The inventors have disclosed a method for manu-facturing electrodes using colloid of solid polymer elec-trolyte in JP-A-7-183035 and JP-A-8-264190. The object of the present invention is to improve these inventions and to provide an assembl~~ of a solid polymer electrolyte membrane and electrodE=s having further higher performances by severely specifying colloid particle size of the solid polymer electrolyte and controlling the thickness of coat, and a solid polymer type fuel cell made using said assembly.
SUMMARY OF THE INVENTION
The present invention relates to a method for producing an assembly ~~omprising a solid polymer electrolyte membrane having electrodes on both sides of the membrane. The method comprises forming at least one of the electrodes by the steps including: (a) preparing a mixed liquid comprising an organic solvent, a noble metal catalyst-supporting carban powder, and a colloid of a solid polymer electrolyte having a particle size distribution range of from 1 nm to less than 400 nm, the colloid being adsorbed to the carbon ~>owder; and (b) coating the mixed liquid on one side of a gas-diffusible layer.
The present invention further relates to an assembly manufactured by the above method and a solid polymer type fuel cell which uses the° assembly.
According to one aespect of the present invention, the solid polymer electrolyte is adsorbed to the catalyst surface, whereby a wide reaction surface area can be secured. Moreover, thickness of the polymer electrolyte layer can be controlled to such a degree that hydrogen and oxygen can easily diffu~~e therethrough, and thus a solid polymer type fuel cell of small concentration polarization and high performance care be obtained.
BRIEF DESCRIPTION OF THE; DRAWINGS
FIG. 1 is a block diagram which shows the steps of manufacture of the assembly of the present invention.
FIG. 2 is a schematic sectional view of the electrode in the example of the present invention.
FIG. 3 is a schematic sectional view of a unit cell of the solid polymer type fuel cell of the present invention.
FIG. 4 is a graph which shows voltage-current characteristics of a fuel cell.
FIG. 5 is a graph which shows voltage-current characteristics of a fuel cell.
FIG. 6 is a graph which shows a particle size distribution of the solid polymer electrolyte of Example 1 of the present invent_~on.
FIG. 7 is a graph which shows a particle size distribution of the solid polymer electrolyte of Example 2 of the present invent_Lon.
FIG. 8 is a graph which shows a particle size distribution of the solid polymer electrolyte of compara-tive example.
FIG. 9 is a graph which shows a pore distribu-tion of carbon black.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a method for manufacturing an assembly comprising a solid polymer elec-trolyte membrane and Electrodes provided on both sides of the membrane, wherein at least one of the electrodes is formed by a step of preparing a mixed liquid containing an organic solvent, a noble metal catalyst-supporting carbon powder and a colloid of a solid polymer electrolyte having a particle size of 1 nm or more and less than 400 nm, said colloid being adsorbed to the carbon powder and a step of forming an electrode :by coating said mixed liquid on one side of a gas-diffusi:ble layer. In more detail, as shown in FIG. l, the steps of manufacture of the assembly may include a first step of preparing a dispersion by dispers-ing a noble metal catalyst-supporting carbon power in an organic solvent, a second step of obtaining a mixed liquid by mixing this dispersion with an alcoholic solution of a solid polymer electrolyte to produce a colloid of the solid electrolyte having a particle size of 1 nm or more and less than 400 nm and simultaneously adsorb the colloid to the carbon powder, a third step of making an electrode by coating the mixed .liquid on one side of a gas-diffusi-ble layer, and a fourth step of pressing the electrode to at least one side of a solid polymer electrolyte membrane to integrally join th~=_m.
Moreover, the steps of manufacture of the assem-bly may include a fir:~t step of preparing a colloidal dis-persion by mixing an organic solvent and an alcoholic solution of a solid polymer electrolyte to produce a col-loid having a particlE=_ size of 1 nm or more and less than 400 nm, a second step of mixing said colloidal dispersion with a noble metal ca1_alyst-supporting carbon powder to prepare a mixed liquid in which the colloid is adsorbed to the carbon powder, and the above third and fourth steps.
According to the above method, the colloid of _ g -solid polymer electrolyte having a severely adjusted par-ticle size can be uniformly adsorbed to carbon powder, and therefore it becomes :possible to disperse catalyst fine particles 3, carbon fine powders 4 and solid polymer elec-trolyte 5 in such a state that they uniformly adhere to each other inside the catalyst layer 2 of electrode 1 as shown in the schematic sectional view of electrode of FIG.
2.
When thickness of the coat of the solid polymer electrolyte is too large, diffusion route of hydrogen and oxygen up to the catalyst surface becomes long to increase concentration polarization of electrode reaction, and when it is too small, transfer route of proton becomes insuffi-cient to cause increase of internal resistance of the electrode. In the present invention, the thickness of the coat can be controlled by adjusting the particle size of colloid of the solid polymer electrolyte.
According to such construction of the catalyst layer 2, the three ch<~nnels of gas channel 7 formed by the void between the carbon powders 4 which is a passage for feeding a fuel gas such as hydrogen or an oxidizing agent gas such as oxygen, proton channel 8 formed by the hydrated solid polymer electrolyte 5, and electron channel 6 formed by mutual connection of the carbon fine powders can be efficiently formed in close to each other inside the same catalyst layer. In FIG. 2, 9 indicates a gas-diffusible layer and .LO indicates a solid polymer electro-lyte.
_ g -According to the present invention, feed of hydrogen and oxygen gas and transfer of proton and elec-tron can be carried out simultaneously and smoothly in a wide range by the following reaction at the hydrogen elec-trode:
H2 ~ 2H+ -~ 2e-and the following rea~~tion at the oxygen electrode:
1/202 + 2H+ + 2e- -i Hz0 Therefore, the reaction rate and the reaction area are increased.
When colloid particle size of the polymer elec-trolyte is less than 400 nm, the colloidal polymer elec-trolyte layer is adsorbed widely and uniformly to the catalyst surface, and thus a polymer electrolyte layer superior in diffusion of hydrogen and oxygen gas can be formed. The critical particle size for the formation of colloid is 1 nm or more. Therefore, the colloid particle size of the polymer e:Lectrolyte is 1 nm or more and less than 400 nm. The carf>on powders used as a carrier for catalyst include thosE~ which are great in pore volume of small pores of less than 10 nm, such as carbon black, and in order to form a three-dimensional electrolyte network in the electrode, the colloid particle size is preferably 10 nm or more. Accora!.ingly, the colloid particle size is more preferably 10 nm or more and less than 400 nm.
The colloid particles may be either monodisperse or polydisperse. Average particle size of primary parti-cles of colloid is preferably 10 nm or more and less than - la -130 nm, more preferably 10 nm or more and less than 70 nm.
Since the electrolyte layer on the surface of catalyst layer is formed with the colloid particles being adsorbed to the catalyst surface, thickness of the elec-trolyte :Layer usu<~lly depends on the size of primary par-ticles o:E colloid.. The colloid particles may be adsorbed in the form of multilayer, and hence the thickness is about 1-3 times the average particle size of primary par-ticles of colloid. Specifically, the thickness of the electrolyte layer is 10 nm or more and less than 400 nm, preferably 10 nm or more and less than 200 nm, more pref-erably 10 nm or more and less than 50 nm.
Size of colloid can be adjusted by changing molecular weight and molecular structure of the polymer electrolyte, and k:.ind and composition of organic solvents at the step of prep~~ration of colloid.
As the organic solvents, there may be suitably used those having a polar group other than hydroxyl group in the molecule and having a carbon chain of 1-8 carbon atoms which bond to the polar group or having a dielectric constant of 3-10 as disclosed in U.S. Pat. No.5,474,875.
Mixing ratio in weight of organic solvent and polymer electrolyte is preferably 10 . 1 - 100 . 1, more preferably 20 . 1 - 70 . 1, and mixing temperature is preferably 30°C or lower, more preferably room temperature.
Furthermore, in order to enhance feeding ability of reaction gases, carbon powders subjected to water repelling treatment;, for example, carbon powders to which 25-70~ in weight ratio of a fluoropolymer is added, may be added to the carbon powders of the present invention.
Amount of the water repelled carbon powders is 10-50~ by weight of the carbon powders supporting the noble metal catalyst.
Examples of the present invention will be explained referring to the accompanying drawings.
Example 1 In the first step, 50 g of carbon fine powders supporting 10-250 by weight of a platinum catalyst were dispersed in n-butyl acetate (CH3COOCH2(CHZ)ZCH3) as an organic solvent.
In the second step, a 9~ ethanolic solution of FlemionrM manufactured by Asahi Glass Co., Ltd. as a solid polymer electrolyte in an amount of 1 g for 60 g of n-butyl acetate was mixed with the above dispersion to produce a white co7_loid. The colloidal solid polymer elec-trolyte was immediately adsorbed to the surface of the carbon fine powdery supporting the catalyst. After a while from completion of addition of all polymer electrolyte solution, stirring was stopped and the supernatant liquid became transparent. When the carbon powders adsorbing the solid polymer electrolyte were allowed to collide with each other by an ultrasonic dispersing device, the adsorbed polymer was also adsorbed to other carbon powders, resulting in bridging agglomeration and the dispersion became pasty.
In the trGird step, the resulting paste was coated on a carbon paper substrate to which 20-60~ by weight of a fluoropolymer was previously added (manufactured by 'roray Industries, Inc.). The bridging agglomeration which occurred in the second step prevented the catalyst fine F>articles from penetrating into the carbon paper and only the solvent was removed and filtered, whereby it became F~ossible to mold the catalyst layer on the surface of the substrate.
In the fourth step, the above electrodes were hot pressed on both. sides of NafioriMmembrane manufactured by DuPont de Nemours, E.,I. Co., by application of a pres-sure of 5-100 kg/cm2 at 120-200°C to make a cell A.
Example :?
Cell B was produced in the same manner as in Example 1, except that "5$ Nafion solution" manufactured by Aldri<:h Chemical Co., Ltd. was used as the solid poly-mer electrolyte in the second step.
Comparative Example Cell X wa:~ produced in the same manner as in Example 1., except that "5~ Nafion solution" manufactured by Aldrich Chemical Co., Ltd. was used as the solid poly-mer electrolyte and the mixing was carried out under heat-ing at 50°C in the ~~econd step.
FIG. 3 shows a schematic sectional view of a unit cell of the manufactured solid polymer type fuel cell.
In FIG. 3, 10 indicate=_s a solid polymer electrolyte mem-brane. In the above Examples and Comparative Example, "Nafion 112 membrane" manufactured by DuPont de Nemours,E.I., Co. was used as the solid polymer electro-lyte membrane 10. In FIG. 3, 11 and 12 indicate a porous negative electrode and a porous positive electrode, respectively. The amc>unt of the solid polymer electrolyte added was 1.0 mg/cm2 per apparent electrode area for both the electrodes, but the same characteristics were obtained with addition of the electrolyte in the range of 0.1-3.0 mg/cm2. The amount of platinum was 0.5 mg/cm2 similarly per apparent electrode area. Discharge test was conducted by feeding hydrogen gas moisturized at 90°C to the negative electrode side and ox5rgen gas moisturized at 80°C to the positive electrode side from the inlet of the cell toward the outlet of the celT_, respectively.
FIG. 4 shown> voltage-current characteristics of the cells made in Examples 1 and 2 and Comparative Example.
Current densities of cells A and B of the present inven-tion and cell X of Comparative Example at 500 mV were 1200, 1150, and 360 mA/cmz, respectively. The cells of the pres-ent invention showed characteristics of more than 3 times that of Comparative E}:ample. FIG. 5 shows characteristics obtained by Tafel plotting the respective characteristics of FIG. 4. Current densities of cells A and B of the pres-ent invention and cell. X of Comparative Example at 850 mV
were 60, 26, and 10 mA/cm2, respectively. The straight line portion of the Tafel plotted characteristics shows activation polarization, namely, characteristics of the region where polarization caused by charge transport de-termines the rate of reaction, and current density of this region at a given voltage can approximate to the reaction area of the electrode. Therefore, it was found that cell A
of Example 1 of the present invention had a reaction area of 6 times that of cell X of Comparative Example, and cell B had a reaction area of 2.6 times that of cell X.
FIGS. 6-8 show particle size distributions of colloids A', B', and :K' prepared by mixing the solid poly-mer electrolyte used :in Examples 1 and 2 and Comparative Example with n-butyl acetate solvent, which were measured by cumulant analysis using a dynamic light scattering photometer DLS-7000 manufactured by Ohtsuka Denshi Co., Ltd. Table 1 shows average particle size, primary particle size, range of particle size distribution and polydisperse index of the colloid particles. A polydisperse index of 0.1 or less means monodisperse, and that of more than 0.1 means polydisperse.
Table 1 A~ B, X, Average particle size 102 154 514 of colloid (nm) Average particle size 16 122 424 of primary particles (nm) Range of particle size 13~-340 73~'351 282~-1200 distribution (nm) Polydisperse index 0.207 0.123 0.073 It was seen that colloid A' of Example 1 had a distribution range of 13-340 nm and an average particle size of 102 nm, and was in polydisperse state, but most of the colloid was occupied by particles of about 16 nm. It was seen that colloid B' of Example 2 had a distribution range of 73-351 nm and an average particle size of 154 nm, was in slightly polyd:isperse state, and had an average particle size of primary particles of about 122 nm. On the other hand, it was seen that colloid X' of Comparative Example comprised particles of monodisperse state having a distribution range of 282-1200 nm and having a primary particle size of aboui~ 424 nm.
Since the e7_ectrolyte layer on the surface of catalyst is formed by the adsorption of primary particles of the above-mentioned colloid to the surface of catalyst, the thickness of the .Layer depends on the primary parti-cles of the colloid, and besides, the primary particles are sometimes adsorbed in the form of multilayer, and therefore, the thickness was 1-3 times the particle size.
As a result, the thic~:ness of the electrolyte layer was 122-366 nm in the case of B' and 16-48 nm in the case of A'. On the other hand., it was 424 nm or more in the case of X'.
It can be seen from the results of particle size distribution of colloid particles of the solid polymer electrolyte that colloids having various particle size can be prepared by changing kind of solid polymer materials, mixing conditions and the like by the method of the pres-ent invention. It can be seen from the results of FIGS. 4 and 5 that state of colloid greatly affects the cell char-acteristics. Cells A and B of Examples 1 and 2 in which the particle size of colloid was distributed in the range of 10 nm or more and less than 400 nm showed high charac-teristics and the comparative cell X in which the colloid particles had an average particle size of 400 nm or more showed low characteristics. It is considered that in cells A and B, the solid polymer electrolyte was adsorbed widely, thinly and uniformly to the surface of catalyst and the polymer electrolyte layer was formed in such a thickness that hydrogen and oxygen gas can satisfactorily diffuse therethrough. On the other hand, cell X had a small reac-tion area and showed low characteristics in the high cur-rent den:>ity region. It is considered that this is because since co7_loid X' wars large, the solid polymer electrolyte layer could not be uniformly adsorbed to the surface of catalyst to reduce 'the reaction area and since thickness of the adsorbed pol,~rmer electrolyte layer was great, dif-fusion route of hydrogen and oxygen was long, resulting in increase of concentration overvoltage to cause deteriora-tion of characteristics in the high current density region.
That is, it is considered that an optimum polymer electro-lyte layer can be formed by the present invention.
FIG. 9 shows results of pore distribution of typical carbon blacks used as a carrier for catalyst which were obtained by nitrogen gas adsorption method. KetjenTM
Black 600D (KB600JD) and Ketjen Black EC (KBEC) manufac-tured by Lion Co., htd. and acetylene blacks (AB, AB1, AB2, AB3, and AB18) manufactured by Denki Kagaku Kogyo Co., Ltd.
were used as the carbon blacks. It can be seen from FIG. 9 that these carbon blacks have a large volume for the pores of 10 nm or less. Since primary particle size of carbon black is 10 nm or more, these pores can be considered to be those formed on the surface of carbon black particles.
Therefore, it is preferred for forming a three-dimensional electrolyte network in the electrode that thickness of the solid polymer electrolyte layer formed on these carbon blacks is 10 nm or more.
The kind and amount of the above-mentioned organic solvents can be experimentally optionally selected so that particle size of the colloid is in the range of 1 nm or more and less than 400 nm. The Examples of the pres-ent invention describes the representative values and do not restrict the present invention.
Moreover, i:n the above Examples, solutions of Flemion and Nafion were used as representative examples of polymers comprising a copolymer of tetrafluoroethylene and perfluorovinyl ether as the solid polymer electrolyte, but the polymers are not limited to these examples as far as they are polymer electrolyte having proton exchange group, and the similar effects were obtained by using polymers of different molecular structures. For example, there may be used perfluorovinyl ethers, polymers of different side chain molecular length, polymers comprising a copolymer of styrene and vinyl benzene, and other hydrocarbon polymer electrolytes.
Furthermore, in the above Examples, a hydrogen-oxygen fuel cell was taken up, but the present invention can also be applied to fuel cells which use modified hydrogen obtained from methanol, natural gases, naphtha, etc., fuel cells which use air as oxidizing agent, and liquid fuel cells which directly use methanol as a fuel.
Moreover, in the above Examples, fuel cells were constructed using an assembly of a solid polymer electro-lyte and an electrode, but the assembly can be effectively applied to generators or purifiers of oxygen, ozone, hydrogen, etc. and various gas sensors such as oxygen sen-sor and alcohol sensor.
As explained above, according to the present invention, contact between the solid polymer electrolyte and the catalyst in the electrode and dispersing state of them in the electrode can be improved, and the three chan-nels of the gas channel formed by the voids between fine carbon powders which is a channel for feeding fuel gases such as hydrogen and oxidizing agent gases such as oxygen, the proton channel fox-med by the hydrous solid polymer electrolyte and the electron channel formed by mutual con-nection of carbon fine powders are formed very close to each other in the same catalyst layer, and the reaction area is increased.
Therefore, feeding of hydrogen and oxygen gas and transfer of proton and electron are carried out smoothly and in a wide range, and thus the present inven-tion can provide solid polymer type fuel cells which ex-hibit higher discharge performance.
Hitherto, in order to increase the three face interface, it has been attempted to apply a layer prepared by mixing and dispersing an electrode material and a solid polymer electrolyte to the interface between the membrane and a porous electrodES. For example, JP-B-62-61118 and JP-B-62-61119 disclose a method which comprises coating a mixture of a solution of solid polymer electrolyte with a catalyst compound on a solid polymer membrane, hot press-ing the coated membrane on an electrode material and then reducing the catalyst compound or carrying out the coating after the reduction and then carrying out the hot pressing.
JP-A-3-1842E>6 uses a powder prepared by coating a solid polymer electrolyte on the surface of a polymer resin, and JP-A-3-295'_72 employs a method which comprises incorporating a powder of a solid polymer electrolyte into an electrode. JP-A-5-36418 discloses a method which com-prises mixing a solid polymer electrolyte, a catalyst, a carbon powder and a f7_uoropolymer and forming the mixture into a film to form an electrode.
All of the above patent publications use alcohol solvents for the solutions of the solid polymer electro-lyte. Furthermore, U.S. Pat. No.5,211,984 reports a method which comprises preparing an inky dispersion comprising a solid polymer electrolyte, a catalyst and a carbon powder using glycerin or tetrabutylammonium salt as a solvent, casting the dispersion on a polytetrafluoroethylene (hereinafter referred to as "PTFE") film, and then trans-ferring it onto the surface of a solid polymer electrolyte membrane or a method which comprises changing the exchang-ing group of a solid polymer electrolyte membrane to Na type, coating the above inky dispersion on the surface of the membrane, and heating and drying the coat at 125°C or higher to again change the group to H type.
However, wh<~n a catalyst-supporting carbon powder and a water repellent material such as fluoropoly-mer or a carbon powder subjected to water repelling treat-ment are simultaneously added to the solid polymer elec-trolyte solution, much solid polymer electrolyte is adsorbed to the water repellent material or the carbon powder subjected to water repelling treatment, and accord-ingly the degree of contact between the solid polymer electrolyte and the catalyst becomes insufficient and non-uniform, and no sufficient reaction area can be ensured at the interface between the electrode and the ion-exchange membrane.
Moreover, in all of the above methods, it is difficult to coat the solid polymer electrolyte at a suit-able thickness on the surface of the catalyst, and in fact the thickness of coat of the polymer electrolyte cannot be controlled. Therefore, there are problems that the cata-lyst cannot be sufficiently coated on the polymer electro-lyte, resulting in a :mall reaction area or thickness of the coat is too large and diffusion route of hydrogen or oxygen becomes longer to cause increase of concentration over voltage.
Furthermore,. when the dispersion with an alco-holic solvent is coated on a porous substrate or when the inky dispersion is coated on a porous substrate, the dis-persion cannot be dirt=_ctly molded on the surface of the substrate as the dispersion penetrates or permeates into the inside of the substrate and thus, complicated process-ing techniques such as transferring are needed.
Moreover, the above-mentioned method of directly coating the inky dispfsrsion on the surface of the membrane requires complicated production technique of replacing the exchange group of the membrane many times.
"Journal of Electroanalytical Chemistry", 417 (1996) 105-111 mentions that the thinner thickness of polymer electrolyte 1<~yer on the catalyst surface gives the more easy occurrence of diffusion of hydrogen and oxy-gen, and according to FIG. 7, when the thickness is 400 nm, the highest characteristics are obtained. However, this is a result of experiment conducted on a smooth Pt surface, and does not concern with the thickness of the polymer electrolyte layer on the catalyst surface in the catalyst layer of porous electode.
The inventors have disclosed a method for manu-facturing electrodes using colloid of solid polymer elec-trolyte in JP-A-7-183035 and JP-A-8-264190. The object of the present invention is to improve these inventions and to provide an assembl~~ of a solid polymer electrolyte membrane and electrodE=s having further higher performances by severely specifying colloid particle size of the solid polymer electrolyte and controlling the thickness of coat, and a solid polymer type fuel cell made using said assembly.
SUMMARY OF THE INVENTION
The present invention relates to a method for producing an assembly ~~omprising a solid polymer electrolyte membrane having electrodes on both sides of the membrane. The method comprises forming at least one of the electrodes by the steps including: (a) preparing a mixed liquid comprising an organic solvent, a noble metal catalyst-supporting carban powder, and a colloid of a solid polymer electrolyte having a particle size distribution range of from 1 nm to less than 400 nm, the colloid being adsorbed to the carbon ~>owder; and (b) coating the mixed liquid on one side of a gas-diffusible layer.
The present invention further relates to an assembly manufactured by the above method and a solid polymer type fuel cell which uses the° assembly.
According to one aespect of the present invention, the solid polymer electrolyte is adsorbed to the catalyst surface, whereby a wide reaction surface area can be secured. Moreover, thickness of the polymer electrolyte layer can be controlled to such a degree that hydrogen and oxygen can easily diffu~~e therethrough, and thus a solid polymer type fuel cell of small concentration polarization and high performance care be obtained.
BRIEF DESCRIPTION OF THE; DRAWINGS
FIG. 1 is a block diagram which shows the steps of manufacture of the assembly of the present invention.
FIG. 2 is a schematic sectional view of the electrode in the example of the present invention.
FIG. 3 is a schematic sectional view of a unit cell of the solid polymer type fuel cell of the present invention.
FIG. 4 is a graph which shows voltage-current characteristics of a fuel cell.
FIG. 5 is a graph which shows voltage-current characteristics of a fuel cell.
FIG. 6 is a graph which shows a particle size distribution of the solid polymer electrolyte of Example 1 of the present invent_~on.
FIG. 7 is a graph which shows a particle size distribution of the solid polymer electrolyte of Example 2 of the present invent_Lon.
FIG. 8 is a graph which shows a particle size distribution of the solid polymer electrolyte of compara-tive example.
FIG. 9 is a graph which shows a pore distribu-tion of carbon black.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a method for manufacturing an assembly comprising a solid polymer elec-trolyte membrane and Electrodes provided on both sides of the membrane, wherein at least one of the electrodes is formed by a step of preparing a mixed liquid containing an organic solvent, a noble metal catalyst-supporting carbon powder and a colloid of a solid polymer electrolyte having a particle size of 1 nm or more and less than 400 nm, said colloid being adsorbed to the carbon powder and a step of forming an electrode :by coating said mixed liquid on one side of a gas-diffusi:ble layer. In more detail, as shown in FIG. l, the steps of manufacture of the assembly may include a first step of preparing a dispersion by dispers-ing a noble metal catalyst-supporting carbon power in an organic solvent, a second step of obtaining a mixed liquid by mixing this dispersion with an alcoholic solution of a solid polymer electrolyte to produce a colloid of the solid electrolyte having a particle size of 1 nm or more and less than 400 nm and simultaneously adsorb the colloid to the carbon powder, a third step of making an electrode by coating the mixed .liquid on one side of a gas-diffusi-ble layer, and a fourth step of pressing the electrode to at least one side of a solid polymer electrolyte membrane to integrally join th~=_m.
Moreover, the steps of manufacture of the assem-bly may include a fir:~t step of preparing a colloidal dis-persion by mixing an organic solvent and an alcoholic solution of a solid polymer electrolyte to produce a col-loid having a particlE=_ size of 1 nm or more and less than 400 nm, a second step of mixing said colloidal dispersion with a noble metal ca1_alyst-supporting carbon powder to prepare a mixed liquid in which the colloid is adsorbed to the carbon powder, and the above third and fourth steps.
According to the above method, the colloid of _ g -solid polymer electrolyte having a severely adjusted par-ticle size can be uniformly adsorbed to carbon powder, and therefore it becomes :possible to disperse catalyst fine particles 3, carbon fine powders 4 and solid polymer elec-trolyte 5 in such a state that they uniformly adhere to each other inside the catalyst layer 2 of electrode 1 as shown in the schematic sectional view of electrode of FIG.
2.
When thickness of the coat of the solid polymer electrolyte is too large, diffusion route of hydrogen and oxygen up to the catalyst surface becomes long to increase concentration polarization of electrode reaction, and when it is too small, transfer route of proton becomes insuffi-cient to cause increase of internal resistance of the electrode. In the present invention, the thickness of the coat can be controlled by adjusting the particle size of colloid of the solid polymer electrolyte.
According to such construction of the catalyst layer 2, the three ch<~nnels of gas channel 7 formed by the void between the carbon powders 4 which is a passage for feeding a fuel gas such as hydrogen or an oxidizing agent gas such as oxygen, proton channel 8 formed by the hydrated solid polymer electrolyte 5, and electron channel 6 formed by mutual connection of the carbon fine powders can be efficiently formed in close to each other inside the same catalyst layer. In FIG. 2, 9 indicates a gas-diffusible layer and .LO indicates a solid polymer electro-lyte.
_ g -According to the present invention, feed of hydrogen and oxygen gas and transfer of proton and elec-tron can be carried out simultaneously and smoothly in a wide range by the following reaction at the hydrogen elec-trode:
H2 ~ 2H+ -~ 2e-and the following rea~~tion at the oxygen electrode:
1/202 + 2H+ + 2e- -i Hz0 Therefore, the reaction rate and the reaction area are increased.
When colloid particle size of the polymer elec-trolyte is less than 400 nm, the colloidal polymer elec-trolyte layer is adsorbed widely and uniformly to the catalyst surface, and thus a polymer electrolyte layer superior in diffusion of hydrogen and oxygen gas can be formed. The critical particle size for the formation of colloid is 1 nm or more. Therefore, the colloid particle size of the polymer e:Lectrolyte is 1 nm or more and less than 400 nm. The carf>on powders used as a carrier for catalyst include thosE~ which are great in pore volume of small pores of less than 10 nm, such as carbon black, and in order to form a three-dimensional electrolyte network in the electrode, the colloid particle size is preferably 10 nm or more. Accora!.ingly, the colloid particle size is more preferably 10 nm or more and less than 400 nm.
The colloid particles may be either monodisperse or polydisperse. Average particle size of primary parti-cles of colloid is preferably 10 nm or more and less than - la -130 nm, more preferably 10 nm or more and less than 70 nm.
Since the electrolyte layer on the surface of catalyst layer is formed with the colloid particles being adsorbed to the catalyst surface, thickness of the elec-trolyte :Layer usu<~lly depends on the size of primary par-ticles o:E colloid.. The colloid particles may be adsorbed in the form of multilayer, and hence the thickness is about 1-3 times the average particle size of primary par-ticles of colloid. Specifically, the thickness of the electrolyte layer is 10 nm or more and less than 400 nm, preferably 10 nm or more and less than 200 nm, more pref-erably 10 nm or more and less than 50 nm.
Size of colloid can be adjusted by changing molecular weight and molecular structure of the polymer electrolyte, and k:.ind and composition of organic solvents at the step of prep~~ration of colloid.
As the organic solvents, there may be suitably used those having a polar group other than hydroxyl group in the molecule and having a carbon chain of 1-8 carbon atoms which bond to the polar group or having a dielectric constant of 3-10 as disclosed in U.S. Pat. No.5,474,875.
Mixing ratio in weight of organic solvent and polymer electrolyte is preferably 10 . 1 - 100 . 1, more preferably 20 . 1 - 70 . 1, and mixing temperature is preferably 30°C or lower, more preferably room temperature.
Furthermore, in order to enhance feeding ability of reaction gases, carbon powders subjected to water repelling treatment;, for example, carbon powders to which 25-70~ in weight ratio of a fluoropolymer is added, may be added to the carbon powders of the present invention.
Amount of the water repelled carbon powders is 10-50~ by weight of the carbon powders supporting the noble metal catalyst.
Examples of the present invention will be explained referring to the accompanying drawings.
Example 1 In the first step, 50 g of carbon fine powders supporting 10-250 by weight of a platinum catalyst were dispersed in n-butyl acetate (CH3COOCH2(CHZ)ZCH3) as an organic solvent.
In the second step, a 9~ ethanolic solution of FlemionrM manufactured by Asahi Glass Co., Ltd. as a solid polymer electrolyte in an amount of 1 g for 60 g of n-butyl acetate was mixed with the above dispersion to produce a white co7_loid. The colloidal solid polymer elec-trolyte was immediately adsorbed to the surface of the carbon fine powdery supporting the catalyst. After a while from completion of addition of all polymer electrolyte solution, stirring was stopped and the supernatant liquid became transparent. When the carbon powders adsorbing the solid polymer electrolyte were allowed to collide with each other by an ultrasonic dispersing device, the adsorbed polymer was also adsorbed to other carbon powders, resulting in bridging agglomeration and the dispersion became pasty.
In the trGird step, the resulting paste was coated on a carbon paper substrate to which 20-60~ by weight of a fluoropolymer was previously added (manufactured by 'roray Industries, Inc.). The bridging agglomeration which occurred in the second step prevented the catalyst fine F>articles from penetrating into the carbon paper and only the solvent was removed and filtered, whereby it became F~ossible to mold the catalyst layer on the surface of the substrate.
In the fourth step, the above electrodes were hot pressed on both. sides of NafioriMmembrane manufactured by DuPont de Nemours, E.,I. Co., by application of a pres-sure of 5-100 kg/cm2 at 120-200°C to make a cell A.
Example :?
Cell B was produced in the same manner as in Example 1, except that "5$ Nafion solution" manufactured by Aldri<:h Chemical Co., Ltd. was used as the solid poly-mer electrolyte in the second step.
Comparative Example Cell X wa:~ produced in the same manner as in Example 1., except that "5~ Nafion solution" manufactured by Aldrich Chemical Co., Ltd. was used as the solid poly-mer electrolyte and the mixing was carried out under heat-ing at 50°C in the ~~econd step.
FIG. 3 shows a schematic sectional view of a unit cell of the manufactured solid polymer type fuel cell.
In FIG. 3, 10 indicate=_s a solid polymer electrolyte mem-brane. In the above Examples and Comparative Example, "Nafion 112 membrane" manufactured by DuPont de Nemours,E.I., Co. was used as the solid polymer electro-lyte membrane 10. In FIG. 3, 11 and 12 indicate a porous negative electrode and a porous positive electrode, respectively. The amc>unt of the solid polymer electrolyte added was 1.0 mg/cm2 per apparent electrode area for both the electrodes, but the same characteristics were obtained with addition of the electrolyte in the range of 0.1-3.0 mg/cm2. The amount of platinum was 0.5 mg/cm2 similarly per apparent electrode area. Discharge test was conducted by feeding hydrogen gas moisturized at 90°C to the negative electrode side and ox5rgen gas moisturized at 80°C to the positive electrode side from the inlet of the cell toward the outlet of the celT_, respectively.
FIG. 4 shown> voltage-current characteristics of the cells made in Examples 1 and 2 and Comparative Example.
Current densities of cells A and B of the present inven-tion and cell X of Comparative Example at 500 mV were 1200, 1150, and 360 mA/cmz, respectively. The cells of the pres-ent invention showed characteristics of more than 3 times that of Comparative E}:ample. FIG. 5 shows characteristics obtained by Tafel plotting the respective characteristics of FIG. 4. Current densities of cells A and B of the pres-ent invention and cell. X of Comparative Example at 850 mV
were 60, 26, and 10 mA/cm2, respectively. The straight line portion of the Tafel plotted characteristics shows activation polarization, namely, characteristics of the region where polarization caused by charge transport de-termines the rate of reaction, and current density of this region at a given voltage can approximate to the reaction area of the electrode. Therefore, it was found that cell A
of Example 1 of the present invention had a reaction area of 6 times that of cell X of Comparative Example, and cell B had a reaction area of 2.6 times that of cell X.
FIGS. 6-8 show particle size distributions of colloids A', B', and :K' prepared by mixing the solid poly-mer electrolyte used :in Examples 1 and 2 and Comparative Example with n-butyl acetate solvent, which were measured by cumulant analysis using a dynamic light scattering photometer DLS-7000 manufactured by Ohtsuka Denshi Co., Ltd. Table 1 shows average particle size, primary particle size, range of particle size distribution and polydisperse index of the colloid particles. A polydisperse index of 0.1 or less means monodisperse, and that of more than 0.1 means polydisperse.
Table 1 A~ B, X, Average particle size 102 154 514 of colloid (nm) Average particle size 16 122 424 of primary particles (nm) Range of particle size 13~-340 73~'351 282~-1200 distribution (nm) Polydisperse index 0.207 0.123 0.073 It was seen that colloid A' of Example 1 had a distribution range of 13-340 nm and an average particle size of 102 nm, and was in polydisperse state, but most of the colloid was occupied by particles of about 16 nm. It was seen that colloid B' of Example 2 had a distribution range of 73-351 nm and an average particle size of 154 nm, was in slightly polyd:isperse state, and had an average particle size of primary particles of about 122 nm. On the other hand, it was seen that colloid X' of Comparative Example comprised particles of monodisperse state having a distribution range of 282-1200 nm and having a primary particle size of aboui~ 424 nm.
Since the e7_ectrolyte layer on the surface of catalyst is formed by the adsorption of primary particles of the above-mentioned colloid to the surface of catalyst, the thickness of the .Layer depends on the primary parti-cles of the colloid, and besides, the primary particles are sometimes adsorbed in the form of multilayer, and therefore, the thickness was 1-3 times the particle size.
As a result, the thic~:ness of the electrolyte layer was 122-366 nm in the case of B' and 16-48 nm in the case of A'. On the other hand., it was 424 nm or more in the case of X'.
It can be seen from the results of particle size distribution of colloid particles of the solid polymer electrolyte that colloids having various particle size can be prepared by changing kind of solid polymer materials, mixing conditions and the like by the method of the pres-ent invention. It can be seen from the results of FIGS. 4 and 5 that state of colloid greatly affects the cell char-acteristics. Cells A and B of Examples 1 and 2 in which the particle size of colloid was distributed in the range of 10 nm or more and less than 400 nm showed high charac-teristics and the comparative cell X in which the colloid particles had an average particle size of 400 nm or more showed low characteristics. It is considered that in cells A and B, the solid polymer electrolyte was adsorbed widely, thinly and uniformly to the surface of catalyst and the polymer electrolyte layer was formed in such a thickness that hydrogen and oxygen gas can satisfactorily diffuse therethrough. On the other hand, cell X had a small reac-tion area and showed low characteristics in the high cur-rent den:>ity region. It is considered that this is because since co7_loid X' wars large, the solid polymer electrolyte layer could not be uniformly adsorbed to the surface of catalyst to reduce 'the reaction area and since thickness of the adsorbed pol,~rmer electrolyte layer was great, dif-fusion route of hydrogen and oxygen was long, resulting in increase of concentration overvoltage to cause deteriora-tion of characteristics in the high current density region.
That is, it is considered that an optimum polymer electro-lyte layer can be formed by the present invention.
FIG. 9 shows results of pore distribution of typical carbon blacks used as a carrier for catalyst which were obtained by nitrogen gas adsorption method. KetjenTM
Black 600D (KB600JD) and Ketjen Black EC (KBEC) manufac-tured by Lion Co., htd. and acetylene blacks (AB, AB1, AB2, AB3, and AB18) manufactured by Denki Kagaku Kogyo Co., Ltd.
were used as the carbon blacks. It can be seen from FIG. 9 that these carbon blacks have a large volume for the pores of 10 nm or less. Since primary particle size of carbon black is 10 nm or more, these pores can be considered to be those formed on the surface of carbon black particles.
Therefore, it is preferred for forming a three-dimensional electrolyte network in the electrode that thickness of the solid polymer electrolyte layer formed on these carbon blacks is 10 nm or more.
The kind and amount of the above-mentioned organic solvents can be experimentally optionally selected so that particle size of the colloid is in the range of 1 nm or more and less than 400 nm. The Examples of the pres-ent invention describes the representative values and do not restrict the present invention.
Moreover, i:n the above Examples, solutions of Flemion and Nafion were used as representative examples of polymers comprising a copolymer of tetrafluoroethylene and perfluorovinyl ether as the solid polymer electrolyte, but the polymers are not limited to these examples as far as they are polymer electrolyte having proton exchange group, and the similar effects were obtained by using polymers of different molecular structures. For example, there may be used perfluorovinyl ethers, polymers of different side chain molecular length, polymers comprising a copolymer of styrene and vinyl benzene, and other hydrocarbon polymer electrolytes.
Furthermore, in the above Examples, a hydrogen-oxygen fuel cell was taken up, but the present invention can also be applied to fuel cells which use modified hydrogen obtained from methanol, natural gases, naphtha, etc., fuel cells which use air as oxidizing agent, and liquid fuel cells which directly use methanol as a fuel.
Moreover, in the above Examples, fuel cells were constructed using an assembly of a solid polymer electro-lyte and an electrode, but the assembly can be effectively applied to generators or purifiers of oxygen, ozone, hydrogen, etc. and various gas sensors such as oxygen sen-sor and alcohol sensor.
As explained above, according to the present invention, contact between the solid polymer electrolyte and the catalyst in the electrode and dispersing state of them in the electrode can be improved, and the three chan-nels of the gas channel formed by the voids between fine carbon powders which is a channel for feeding fuel gases such as hydrogen and oxidizing agent gases such as oxygen, the proton channel fox-med by the hydrous solid polymer electrolyte and the electron channel formed by mutual con-nection of carbon fine powders are formed very close to each other in the same catalyst layer, and the reaction area is increased.
Therefore, feeding of hydrogen and oxygen gas and transfer of proton and electron are carried out smoothly and in a wide range, and thus the present inven-tion can provide solid polymer type fuel cells which ex-hibit higher discharge performance.
Claims (9)
1. A method for producing an assembly comprising a solid polymer electrolyte membrane having electrodes on both sides of the membrane, said method comprising:
forming at least one of the electrodes by steps including:
(a) preparing a mixed liquid comprising an organic solvent, a noble metal catalyst-supporting carbon powder, and a colloid of a solid polymer electrolyte having a particle size distribution range of from 1 nm to less than 400 nm, said colloid being adsorbed to the carbon powder;
and (b) coating said mixed liquid on one side of a gas-diffusible layer.
forming at least one of the electrodes by steps including:
(a) preparing a mixed liquid comprising an organic solvent, a noble metal catalyst-supporting carbon powder, and a colloid of a solid polymer electrolyte having a particle size distribution range of from 1 nm to less than 400 nm, said colloid being adsorbed to the carbon powder;
and (b) coating said mixed liquid on one side of a gas-diffusible layer.
2. A method according to claim 1, wherein step (a) comprises:
preparing a dispersion by dispersing the noble metal catalyst-supporting carbon powder in the organic solvent;
and mixing said dispersion and an alcoholic solution of a solid polymer electrolyte to produce the colloid of the solid polymer electrolyte and to simultaneously adsorb the colloid to the carbon powder.
preparing a dispersion by dispersing the noble metal catalyst-supporting carbon powder in the organic solvent;
and mixing said dispersion and an alcoholic solution of a solid polymer electrolyte to produce the colloid of the solid polymer electrolyte and to simultaneously adsorb the colloid to the carbon powder.
3. A method according to claim 1, wherein step (a) comprises:
preparing a colloid dispersion by mixing the organic solvent and an alcoholic solution of a solid polymer electrolyte; and mixing the colloid dispersion and the noble metal catalyst-supporting carbon powder to adsorb the colloid to the carbon powder.
preparing a colloid dispersion by mixing the organic solvent and an alcoholic solution of a solid polymer electrolyte; and mixing the colloid dispersion and the noble metal catalyst-supporting carbon powder to adsorb the colloid to the carbon powder.
4. A method according to claim 1, 2, or 3, wherein the particle size of the colloid is from 10 nm to less than 400 nm.
5. A method according to claim 1, 2, or 3, wherein an average particle size of primary particles of the colloid is from 10 nm to less than 130 nm.
6. A method according to any one of claims 1 to 5, wherein the carbon powder contains water repelling carbon powder.
7. An assembly produced by the method according to any one of claims 1 to 6.
8. An assembly produced by the method according to any one of claims 1 to 6, wherein an electrolyte layer formed with particles of the colloid has a thickness of from 10 nm to less than 400 nm.
9. A solid polymer electrolyte fuel cell made using the assembly according to claim 7 or 8.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09-104470 | 1997-04-22 | ||
| JP9104470A JPH10302805A (en) | 1997-04-22 | 1997-04-22 | Assembly of solid polymer electrolyte membrane and electrode, method for producing the same, and fuel cell using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2235431A1 CA2235431A1 (en) | 1998-10-22 |
| CA2235431C true CA2235431C (en) | 2003-04-15 |
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Country Status (4)
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| US (1) | US6060187A (en) |
| EP (1) | EP0874413A3 (en) |
| JP (1) | JPH10302805A (en) |
| CA (1) | CA2235431C (en) |
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| US6403245B1 (en) | 1999-05-21 | 2002-06-11 | Microcoating Technologies, Inc. | Materials and processes for providing fuel cells and active membranes |
| JP2001015122A (en) * | 1999-06-30 | 2001-01-19 | Tanaka Kikinzoku Kogyo Kk | Catalyst for polymer electrolyte fuel cell and polymer electrolyte fuel cell |
| JP4433518B2 (en) * | 1999-07-30 | 2010-03-17 | アイシン精機株式会社 | Solid polymer electrolyte fuel cell |
| JP4734688B2 (en) * | 2000-02-01 | 2011-07-27 | 東レ株式会社 | ELECTRODE AND MANUFACTURING METHOD THEREOF, MEMBRANE-ELECTRODE COMPOSITION AND MANUFACTURING METHOD THEREOF, AND ELECTROCHEMICAL DEVICE, WATER ELECTROLYTIC DEVICE, FUEL CELL, MOBILE BODY USING THE SAME, AND AUTOMOBILE |
| EP2124275B1 (en) | 2000-06-22 | 2011-08-24 | Panasonic Corporation | Apparatus for manufacturing electrode for polymer electrolyte fuel cell, and method of manufacturing the same |
| US7201993B2 (en) * | 2000-08-04 | 2007-04-10 | Matsushita Electric Industrial Co., Ltd. | Polymer electrolyte fuel cell |
| US20040053111A1 (en) | 2000-10-31 | 2004-03-18 | Koichi Matsumoto | Electrode for solid polymer type fuel cell |
| EP1244165A3 (en) * | 2001-03-19 | 2006-03-29 | Ube Industries, Ltd. | Electrode base material for fuel cell |
| US20030206710A1 (en) * | 2001-09-14 | 2003-11-06 | Ferman Ahmet Mufit | Audiovisual management system |
| JP2003317729A (en) * | 2002-04-26 | 2003-11-07 | Ube Ind Ltd | Fuel cell electrode using porous graphite film, membrane-electrode assembly, and fuel cell |
| KR100480782B1 (en) * | 2002-10-26 | 2005-04-07 | 삼성에스디아이 주식회사 | Membrane and electrode assembly of full cell, production method of the same and fuel cell employing the same |
| US7569302B2 (en) | 2002-11-05 | 2009-08-04 | Panasonic Corporation | Fuel cell for generating electric power |
| US20040107869A1 (en) * | 2002-12-10 | 2004-06-10 | 3M Innovative Properties Company | Catalyst ink |
| US7364813B2 (en) * | 2003-09-12 | 2008-04-29 | Matsushita Electric Industrial Co., Ltd. | Ink for forming catalyst layer, and electrode and membrane-electrode assembly using the same |
| JP4817622B2 (en) * | 2004-07-12 | 2011-11-16 | 株式会社巴川製紙所 | Method for producing gas diffusion electrode for polymer electrolyte fuel cell |
| JP2006310216A (en) * | 2005-05-02 | 2006-11-09 | Toyota Motor Corp | Method for producing coating solution for forming catalyst electrode layer |
| WO2008004645A1 (en) * | 2006-07-04 | 2008-01-10 | Sumitomo Chemical Company, Limited | Polymer electrolyte emulsion and use thereof |
| WO2008004644A1 (en) | 2006-07-04 | 2008-01-10 | Sumitomo Chemical Company, Limited | Polymer electrolyte emulsion and use thereof |
| JP4506740B2 (en) | 2006-09-14 | 2010-07-21 | トヨタ自動車株式会社 | Catalyst structure for fuel cell, membrane electrode assembly, fuel cell, and method for producing catalyst structure for fuel cell |
| JP2008140719A (en) * | 2006-12-05 | 2008-06-19 | Toyota Motor Corp | Method for producing electrode for fuel cell |
| JP2009245932A (en) * | 2008-03-13 | 2009-10-22 | Toppan Printing Co Ltd | Electrode catalyst ink for fuel cell, electrode catalyst layer, membrane-electrode assembly, and polymer electrolyte fuel cell |
| JP5465840B2 (en) * | 2008-05-13 | 2014-04-09 | 旭化成イーマテリアルズ株式会社 | Method for producing polymer electrolyte fuel cell |
| JP2011008940A (en) * | 2009-06-23 | 2011-01-13 | Toyota Motor Corp | Membrane-electrode assembly, and fuel battery |
| KR101093703B1 (en) * | 2009-06-25 | 2011-12-15 | 삼성에스디아이 주식회사 | Polymer electrolyte membrane for fuel cell and manufacturing method thereof |
| US20130004884A1 (en) * | 2010-03-15 | 2013-01-03 | Katsuyuki Kishi | Slurry for fuel cell electrode catalyst layer, electrode catalyst layer, membrane electrode assembly, and fuel cell |
| JP2025069643A (en) * | 2023-10-18 | 2025-05-01 | 株式会社Ｓｃｒｅｅｎホールディングス | Electrode structure, gas diffusion layer, and water electrolysis device |
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|---|---|---|---|---|
| CA1088149A (en) * | 1976-06-15 | 1980-10-21 | Gerda M. Kohlmayr | Method of fabricating a fuel cell electrode |
| US4959162A (en) * | 1989-02-03 | 1990-09-25 | The United States Of America As Represented By The United States Department Of Energy | Colloidal polypyrrole |
| JPH03184266A (en) * | 1989-12-13 | 1991-08-12 | Toshiba Corp | Fuel cell with solid electrolyte |
| JPH03295172A (en) * | 1990-04-13 | 1991-12-26 | Mitsubishi Heavy Ind Ltd | Junction body of solid polymer electrolyte film and electrode |
| US5211984A (en) * | 1991-02-19 | 1993-05-18 | The Regents Of The University Of California | Membrane catalyst layer for fuel cells |
| JPH0536418A (en) * | 1991-03-13 | 1993-02-12 | Fuji Electric Co Ltd | Solid polymer electrolyte fuel cell and method of manufacturing the same |
| JPH06261119A (en) * | 1993-03-04 | 1994-09-16 | Toshiba Corp | Private branch exchange |
| JP3112214B2 (en) * | 1993-03-08 | 2000-11-27 | 日本電信電話株式会社 | Noise audible immunity evaluation tester |
| JP3422377B2 (en) * | 1993-08-06 | 2003-06-30 | 松下電器産業株式会社 | Method for manufacturing polymer electrolyte fuel cell and polymer electrolyte fuel cell obtained by the method |
| JP3712768B2 (en) * | 1995-01-26 | 2005-11-02 | 松下電器産業株式会社 | Production method of polymer electrolyte fuel cell |
-
1997
- 1997-04-22 JP JP9104470A patent/JPH10302805A/en active Pending
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1998
- 1998-04-08 US US09/056,686 patent/US6060187A/en not_active Expired - Fee Related
- 1998-04-21 CA CA002235431A patent/CA2235431C/en not_active Expired - Fee Related
- 1998-04-22 EP EP98107352A patent/EP0874413A3/en not_active Withdrawn
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| Publication number | Publication date |
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| US6060187A (en) | 2000-05-09 |
| JPH10302805A (en) | 1998-11-13 |
| CA2235431A1 (en) | 1998-10-22 |
| EP0874413A2 (en) | 1998-10-28 |
| EP0874413A3 (en) | 2000-04-12 |
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