CN100466345C

CN100466345C - Fuel cell and gas diffusion electrode for fuel cell

Info

Publication number: CN100466345C
Application number: CNB2005800125580A
Authority: CN
Inventors: 田所健一郎; 饭岛孝; 上代洋; 泽田英明; 松崎洋市
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2004-04-22
Filing date: 2005-04-22
Publication date: 2009-03-04
Anticipated expiration: 2025-04-22
Also published as: CN1947289A

Abstract

Disclosed is a fuel cell comprising a pair of catalyst layers so arranged as to sandwich a proton conductive electrolyte membrane therebetween. The fuel cell is characterized in that at least a catalyst layer of the cathode is composed of a mixture including a catalyst component, an electrolyte material and a carbon material which is composed of a catalyst supporting carbon material carrying the catalyst component and a gas diffusion carbon material not carrying the catalyst component, and the water vapor adsorption of the catalyst supporting carbon material at a relative humidity of 90% at 25 1/2 C is not less than 50 ml/g.

Description

Fuel cell and gas diffusion electrode for fuel cell

Technical field

The present invention relates to fuel cell, relate in particular to and improved the material in the catalyst layer and move, and reduced the electrode of output characteristic excellence of cost and the fuel cell that uses these electrodes by the effective rate of utilization that improves catalyst component.

Background technology

If the structure with the common solid high molecular fuel battery is an example, its electrode structure has following basic structure: one become negative electrode, another catalyst layer that becomes anode clips polyelectrolyte membrane and is bonded together, and then, clip them and be connected with in both sides through carbon paper of water-proofing treatment etc. as gas diffusion layers.

In order from the fuel cell of this basic structure, to take out electric current, supply with oxidizing gas such as oxygen or air from the outside via gaseous diffusion course cathode side respectively, anode side is supplied with reducibility gas such as hydrogen.

For example, when utilizing hydrogen and oxygen, be the H that on the catalyst of anode, takes place by utilizing ₂→ 2H ⁺+ 2e ^-(E ₀=chemical reaction 0V) and the O that on the catalyst of negative electrode, takes place ₂+ 4H ⁺+ 4e ^-→ 2H ₂O (E ₀=1.23V) chemical reaction energy difference and take out electric current.

For this reason, if oxygen or hydrogen can be supplied to catalyst layer inside catalyst gas diffusion path and can then can not take out electric current with proton conduction path and the electrical conductance path of catalyst that be passed to negative electrode at proton that produces on the anode catalyst and electronics respectively not ceded territory to be connected in the catalyst layer at least by branch.

As the catalyst that is suitable for this purpose, use usually the chemical stability height and also with good electrical conductivity body be material with carbon element as carrier, and load thereon the catalyst of structure of catalyst component.

Use this catalyst and proton-conducting material to form catalyst layer, by making the pore that forms in the gap as the material of gas diffusion path, forming separately network, can show function as so-called gas electrode as the electrolyte in proton conduction path with as the material with carbon element of electrical conductance path.

Especially, on the proton conduction path, use perfluorinated sulfonic acid polymer or SDVB sulfonic acid plasma exchanger resin as polymer electrolyte material.These normally used ion exchange resin just show high proton-conducting under moist environment, proton-conducting descends under dry environment.

This is considered to owing in the moving of proton the participation of hydrone must be arranged and follow.Therefore, want to make fuel cell to work expeditiously, usually needing electrolyte is moisture state, and usually needs and supply with steam together to the two poles of the earth gas supplied.

Usually, in order to supply with water to electrolyte, employing will be supplied in the gas humidification of battery, the method that battery is worked below dew point.According to this method, the steam of supplying with in battery is partly condensed, form the drop of cohesion water.

In addition, by above-mentioned cathode reaction, on cathod catalyst, generate water.Although also depend on the operating condition of battery, when reaching supersaturation, the steam of water in catalyst layer that generates just produces cohesion, form the drop of cohesion water.

The drop that the water-setting combinate form that is generated by these reactions becomes, the steam of perhaps supplying with for humidification condenses the drop that forms in catalyst layer can cut off gas diffusion path.This phenomenon is called overflow (flooding), and is obvious at the negative electrode of a large amount of generation water during heavy-current discharge, thereby causes voltage extremely to descend.

So, want to make fuel cell stably to work, need satisfy this limit to carrying out sufficient humidification in the catalyst layer, the limit will be condensed water and promptly will be discharged to the outer this opposite requirement of system.For this reason, all the time, proposed to use PTFE and silane coupling agent etc. catalyst layer inside to be carried out the way of water-proofing treatment.

Proposed by making catalyst layer contain the water proofing property that following material improves catalyst layer inside, cohesion water promptly is discharged to the outer way of system: the spy opens PTFE powder, spy in flat 5-No. 36418 communiques and opens PTFE colloid, spy in flat 4-No. 264367 communiques and open the carbon dust, the spy that have carried out water-proofing treatment with PTFE in flat 7 one No. 183035 communiques and open and carried out the material with carbon element of water-proofing treatment with silane coupling agent in 2000-No. 243404 communiques.

In addition, from the viewpoint of the practicability of fuel cell, important problem is a cutting down cost.Usually in the electrode catalyst of polymer electrolyte fuel cell, anode and negative electrode all use platinum.

In acidic electrolyte baths such as sulfonic acid class proton conductive resin, for the reduction reaction of oxygen and the oxidation reaction of hydrogen, the highest active metal is a platinum, in addition, and from the viewpoint as the stability of metal, the catalyst material that platinum also is best suited for.

Therefore, in order to reduce cost, the use amount that how can cut down platinum is important problem.

As the utilization ratio that improves electrode catalyst, reduce the method for the use amount of platinum, following concrete improvement technology has been proposed.

Open the spy and to have put down in writing following method in flat 9-No. 167622 communiques: with diameter is that the shared volume of pore below the 8nm is 0.5cm ³The following carbon black of/g is as carrier, and carried noble metal, thus the catalyst metals particle is being controlled as the absorption on the carrier pore of the polyelectrolyte that can not distribute of the mobile route of proton.

In addition, in the spy opened 2000-No. 100448 communiques, having put down in writing diameter was that pore below the 6nm accounts for the scheme of the carbon black below 20% of whole pores as carrier.

As improving the diffusible method of reacting gas to the electrode catalyst surface, for example, in the spy opened 2003-No. 201417 communiques, put down in writing following method: with the total measurement (volume) of pore was 0.40～2.3cm ³The carbon black of/g is as catalyst carrier, and the specific area of utilizing the BET method to obtain of described pore is 250～400m ²/ g, particle diameter are that the radius of the opening of 10～17nm, surface formation is 10～30nm.

In the spy opens 2004-No. 82007 communiques, proposed to apply flexibly the concavo-convex catalyst performance that improves of carrier surface.

Promptly, use make the carbon wire side that forms graphene platelet (Graphene sheet) skirt selectivity be exposed to the carbon carrier of pore inwall, average pore diameter is controlled to be 0.5～5.0nm, at pore part supported catalyst particulate, can make the contact area between carrier and the catalyst metals become big thus, its result has not only improved the catalytic activity of catalyst metals itself, and owing to supported catalyst particulate on pore, so can suppress so-called sintering phenomenon.

In addition, preferably to the marginal portion of carbon wire side give-COOH ,-OH etc. contains the oxygen functional group, makes the combination between catalyst metals particulates such as Pt and the carbon carrier become more firm by these oxygen functional groups, and improve catalytic activity.

By effectively utilizing aspect another of countermeasure that above-mentioned platinum reduces cost, just concentrating one's energy to study exploration and can replace catalyst as the platinum of expensive basic essential factor.

Wherein, as catalyst with oxygen reducing ability, all the time, explored the complex compound (H.Jahnke that porphyrin, phthalocyanine, dibenzo four azepine annulenes (Annulene) etc. contain the Macrocyclic compound of metal, M.Schonborn, G.Zimmermann, Topics in CurrentChemistry, Vol.61, p.133～181 (1976)).

Basic idea is the known amboceptors as the oxygen in the organism of these metal complexs, that is, and and by bringing into play (Tang Qianzhen in the reduction reaction that its adsorption capacity to oxygen molecule is applicable to electrochemical oxygen molecule, Japan oiling association will, the 49th volume, No. 4,315～323 pages (2000)).

Research originally, the purpose of discussion be in phosphoric acid type fuel cell as oxygen utmost point Application of Catalyst, but the catalyst degradation that existence is caused by phosphoric acid, catalytic activity be than problems such as platinum are low, the application in phosphoric acid type fuel cell of still being unrealized.

On the other hand, under the situation of polymer solid electrolyte type fuel cell, be considered to avoid the deterioration of the catalyst under the sour environment, the new research of therefore concentrating one's energy again in recent years to have launched.

Want these metal complexs are applicable to as catalyst and catalyst need be fixed on electrode in the practicality on the electrical conductivity body.What use is carbon carrier for this reason.

Specifically, use electronic conductivity height and the big carbon black of surface area.By making up this carbon carrier and metal complex, can be used as electrode catalyst and use continuously.

As the oxygen reduction catalyst that loads on the metal complex on these carbon carriers, its problem has 2 points, any is that overvoltage is also bigger than platinum catalyst, and on the other hand reduzate is not only water (being called 4 electron reaction products), but with the hydrogen peroxide mixture of (being called 2 electron reaction products).

As to superpotential countermeasure, the heat treatment (J.A.R.van Veen, et al., J.Chem.Soc., Faraday Trans.1, Vol.77, p.2827 (1981)) in non-oxidizing atmosphere has been proposed.

But overvoltage and platinum through improving after the heat treatment are in a ratio of more than the 0.1V, still have problem in application facet.

In addition, raising as the yield of 4 electron reaction products, (spy opens flat 11-No. 253811 communiques, F.C.Anson, et al., J.Am.Chem.Soc. to have proposed polynuclear complex, Vol.113, p.9564 (1991)), dimerization materialization (J.P.Collman, et al., the J.Am.Chem.Soc. of porphyrin complex, Vol.102, p.6027 (1980)) etc.But the yield during existence is synthetic etc. is difficult to be applicable to industry, cost height, compares problems such as overvoltage is big with platinum or platinum alloy.

On the other hand, as gas diffusion layers in the configuration of the outside of the catalyst layer at the two poles of the earth, requirement have make gas from the gas passage that forms at barrier film to catalyst layer evenly diffusion function and catalyst layer and barrier film the function of conduction electron, for fuel cell is worked effectively, various technology have been proposed before this.

The technology that wherein makes gas diffusion layers be divided into double-layer structure has successfully shown certain performance.

Usually, this technology is as described below: have because of paying attention to the ground floor that gas diffusibility has larger aperture in the barrier film side, the second layer of catalyst layer side plays the effect as the intermediate layer, electronic conductivity and uniformity between the catalyst layer that is used to guarantee the ground floor of rustic and have microstructure.

For example, in No. 5620807 specification of United States Patent (USP), having proposed with carbon particle or fiber and fluororesin is the water proofing property gas diffusion layers of principal component, has proposed the porosity double-layer structure different with hole diameter as preferred scheme.

In addition, open in flat 10-No. 261421 communiques the spy, as the structure of gas diffusion layers, having proposed to be formed with on the surface of carbon fiber yarn fabric fluororesin and carbon black is the double-layer structure of the layer of principal component.

In addition, in the spy opens 2001-No. 57215 communiques, proposed to have between electrode base material and catalyst layer the intermediate layer of at least two hole diameter distribution center, as preferred scheme, having proposed the carbon particle more than two kinds with different-grain diameter distribution is principal component.

In the catalyst layer that in the past proposes, owing to using PTFE and this compound that blocks the electrical conductance path of catalyst layer of silane coupling agent in order to control water proofing property, so have the problem of the aspect of performance that causes battery performance decline, and because complex proceduresization, use relatively more expensive compound, so have the problem that manufacturing cost increases.

In addition, because the water proofing property of water-repellent material such as these silane coupling agents and PTFE is high, so can not keep the moist environment that is suitable for electrolyte in the catalyst layer inside of having used these compounds, catalyst layer in the past may not necessarily show effective battery performance.

Therefore, in the past,, and, quantitative index was not shown clearly yet about the hydrability of the material that can keep the moist environment that is fit to that helps the catalyst layer design not only not about the motion of the material that can keep the moist environment that is suitable for electrolyte.

Be used for the porous structure that the technology of high performance of the material with carbon element of catalyst carrier lays stress on by control electrode, particularly catalyst layer before this and improve gas diffusibility, thus as concrete method, open the spy that flat 9-No. 167622 communiques, spies open 2000-No. 100448 communiques and the spy opens in the record of 2003-No. 201417 communiques, pore structure to electrode itself stipulates, perhaps the aggregated structure as the carbon black of carrier stipulated.

But, in the process of the gas diffusibility in improving these electrodes, though relate to the high current density zone (0.5A/cm that moves the reason of decision reaction rate (overvoltage) as material ²More than) output voltage improve, but do not relate to the raising of the output characteristic of low current density areas.In order to improve the output voltage of low current density areas, need improve the reactivity of catalyst itself and improve catalyst utilization.

In addition, in the spy opens 2004-No. 82007 communiques, have hollow portion on the carbon carrier of hollow is made of the end face of graphene platelet on the surface, make the catalyst metals long lifetime by supported catalyst metal particle on this hollow, in addition, the diameter of pore is set at the preferable range of 0.5～5.0nm, (wall of pore part is made of the charcoal edge usually but the present inventor is to various active carbons, the diameter of pore is 0.5～5.0nm) to inquire into, its effect is little, need make catalyst long lifetime more for application.

In prior art about the exploitation of platinum alternative catalysts, the reduction reaction of oxygen molecule being carried out modelling and design the molecular structure of the metal complex of catalyst according to quantum chemistry calculation may not be abundant, this result fails successfully to develop such as offering and uses such little metal complex class catalyst of reaction overvoltage.

Therefore, the moist environment that the purpose of this invention is to provide the electrical conductance path in the catalyst layer that can not block fuel cell and keep being fit to, for all very good catalyst layer of proton conduction, electrical conductivity, gaseous diffusion, provide simultaneously by making the output voltage of low current density areas is improved the utilance of catalyst with areas of high current density as the optimization of the material with carbon element of catalyst carrier, use newfound platinum alternative catalysts to reduce the noble metal use amount, the fuel cell that cost is low and output characteristic is excellent.

On the other hand, if the prior art that relates to gas diffusion layers is inquired into, there is following problem in the viewpoint from the characteristic that is guided out high performance catalyst layer to greatest extent particularly.Promptly, in No. 5620807 specification of United States Patent (USP), though stipulated the preferable range of the porosity and hole diameter, but stipulate the carbon particle or the fiber of use, particularly the method for the pore diameter of the minute aperture layer that contacts with catalyst layer of control depends on amount and the molecular weight as the macromolecular material of one of principal component, be difficult to control pore diameter, cannot treat different things as the same.

In addition, open in flat 10-No. 261421 communiques the spy, proposed to relate to the stepped construction of the gas diffusion layers of double-layer structure, and it is identical with No. 5620807 specification of United States Patent (USP), kind or structure for preferred carbon black do not stipulate that it is difficult only will being guided out all catalyst layer performances according to the content that proposes.

Especially, open in flat 10-No. 261421 communiques at No. 5620807 specification of above-mentioned United States Patent (USP) or spy, the method both who guarantees gas diffusion path is the macromolecular material that depends on water proofing property, need the content of the macromolecular material of raising insulating properties for the diffusivity that improves gas, thereby be easy to damage conductivity.

In addition, in the spy opens 2001-No. 57215 communiques, mixing use major diameter carbon particle and the minor diameter carbon particle principal component as the gas diffusion layers that contacts with catalyst layer has been proposed, though mentioned the structure of the material with carbon element that uses itself, but difference according to mechanical fraction, the situation of cutting off gas diffusion path is arranged on the contrary, when the hole that forms in the particle not of the same race gap of using during as gas diffusion path at major diameter carbon particle and minor diameter carbon particle, thereby has the situation that makes the particle movement plugging hole because of the connection pressure of battery, and owing to the configuration change that makes for a long time particle, the situation that the aperture is changed by optimal state is not so claim it is gratifying motion.

Therefore, content only with regard to proposed in the past, when having high performance catalyst layer when being connected with gas diffusion layers, although can show performance to a certain degree, it is difficult being guided out the maximum performance that catalyst layer has.

Thus, the present invention also aims to solve above-mentioned problem, provide a kind of limit to carrying out sufficient humidification in the catalyst layer, the limit will be condensed water and promptly will be discharged to outside the system, even also can not cause overflow when heavy-current discharge, the electrode assembly that catalyst layer and gas diffusion layers is combined to form in order to show stable battery performance is a gas-diffusion electrode.

In order to solve above problem, the inventor studies repeatedly, found that if will be divided into load as the material with carbon element of the principal component of catalyst layer the material with carbon element of catalyst component (below, be called the catalyst carrier material with carbon element) and do not have the supported catalyst composition material with carbon element (below, be called the gaseous diffusion material with carbon element) and contain in catalyst layer, then can prevent to condense the obstruction of the gas diffusion path of water generates, the battery behavior in the time of especially can improving heavy-current discharge significantly; There is optimal scope in the ratio that contains of also finding the gaseous diffusion material with carbon element; In addition, there is suitable scope etc. respectively in the hydrability of also finding catalyst carrier material with carbon element and gas diffused carbon material.

In addition, the relevant material with carbon element that is used for catalyst carrier, carried out wholwe-hearted discussion in order to improve catalyst performance, found that the importantly pore structure of carbon material surface, especially diameter is the structure of the following micropore of 2nm, and the distribution by the chemical functional group that will exist at carbon material surface and as the textural association of the three-dimensional material with carbon elements such as DBP of index in the past can be confirmed tangible performance improvement.

In addition, the metal complex class catalyst that replaces platinum catalyst has been carried out wholwe-hearted research, found that in the metal complex of N4 chelate type, according to quantum chemistry calculation, the O-O bond length of the oxygen molecule that combines with the complex compound central metal in the adsorption structure of metal complex and oxygen molecule is from the catalytic activity of the oxygen reduction reaction that can arrange metal complex, by making the molecular structure optimization of this complex compound, can successfully show the activity identical with platinum, the introducing of above-mentioned gaseous diffusion material with carbon element and the structural optimization of catalyst carrier material with carbon element complement each other, thereby have finished the present invention.

On the other hand, performance for the catalyst layer of bringing into play above-mentioned high performance to greatest extent, with the even diffusion of reacting gas to catalyst layer, the optimization of the moist environment of catalyst layer, promote that the discharge of the water of generation is a purpose, gas diffusion layers has been carried out inquiring into repeatedly, found that gas diffusion layers has double-layer structure, and in the microporous layers adjacent, use the carbon black that glassware for drinking water is had suitable surface characteristic as principal component with catalyst layer, and in order to ensure the mobile route of the mobile route of gas or water material itself to have the structure in the hole that can form suitable size be effective.

In addition, found quantitative index so that selected exactly material with above-mentioned characteristic.That is, discovery will be with carbon black with suitable water vapor adsorption amount the microporous layers of principal component and catalyst layer in abutting connection with setting, and utilizing the specific area of being obtained by DBP oil absorption and nitrogen absorption, selected to have the carbon black of appropriate configuration and be used for microporous layers be effective.

In addition, find by making up aforesaid gas diffusion layers and above-mentioned catalyst layer can carry out significantly high performance, thereby finished the present invention.

Summary of the invention

That is, main idea of the present invention is as follows.

(1) fuel cell, it comprises a pair of catalyst layer that accompanies the proton-conductive electrolyte film, it is characterized in that, at least the catalyst layer of negative electrode is made of the mixture that contains catalyst component, electrolyte and material with carbon element, and above-mentioned material with carbon element by load above-mentioned catalyst component the catalyst carrier material with carbon element and do not have the gaseous diffusion material with carbon element of the above-mentioned catalyst component of load to constitute, the said catalyst carrier material with carbon element is that 90% o'clock water vapor adsorption amount is more than the 50mL/g 25 ℃ and relative humidity.

(2) fuel cell, it comprises a pair of catalyst layer that accompanies the proton-conductive electrolyte film, it is characterized in that, at least the catalyst layer of negative electrode is made of the mixture that contains catalyst component, electrolyte and material with carbon element, and above-mentioned material with carbon element by load above-mentioned catalyst component the catalyst carrier material with carbon element and do not have the gaseous diffusion material with carbon element of the above-mentioned catalyst component of load to constitute, the said catalyst carrier material with carbon element is an active carbon, utilizes BET to estimate the surface area SBET that obtains and satisfies SBET 〉=1500m ²/ g, and diameter is the surface area Smicro (m of the following micropore of 2nm ²/ g) with respect to total pore area Stotal (m ²/ g) ratio satisfies Smicro/Stotal 〉=0.5.

(3) fuel cell of above-mentioned (2) is characterized in that, diameter is that the average diameter of the following micropore of 2nm is 0.7nm～1.5nm in the above-mentioned active carbon.

(4) fuel cell of above-mentioned (2) or (3) is characterized in that, the oxygen content of above-mentioned active carbon is below the 5 quality %.

(5) fuel cell, it comprises a pair of catalyst layer that accompanies the proton-conductive electrolyte film, it is characterized in that, at least the catalyst layer of negative electrode is made of the mixture that contains catalyst component, electrolyte and material with carbon element, and above-mentioned material with carbon element by load above-mentioned catalyst component the catalyst carrier material with carbon element and do not have the gaseous diffusion material with carbon element of the above-mentioned catalyst component of load to constitute, diameter is that the following micropore volume of 2nm is more than the 0.1mL/g in the said catalyst carrier material with carbon element, and the DBP oil absorption of this catalyst carrier material with carbon element is more than the 300mL/100g.

(6) fuel cell of above-mentioned (5) is characterized in that, the specific area SBET that utilizes the BET method to obtain of said catalyst carrier material with carbon element is 500m ²More than/the g.

(7) fuel cell of any one in above-mentioned (1)～(6) is characterized in that, the content of above-mentioned gas diffused carbon material in catalyst layer is 5 quality %～50 quality %.

(8) fuel cell of any one in above-mentioned (1)～(7) is characterized in that, above-mentioned gas diffused carbon material is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity.

(9) fuel cell of any one in above-mentioned (1)～(8) is characterized in that, above-mentioned gas diffused carbon material is that 90% o'clock water vapor adsorption amount is 1mL/g～50mL/g 25 ℃ and relative humidity.

(10) fuel cell of any one in above-mentioned (1)～(9) is characterized in that above-mentioned catalyst component contains the metal complex of N4 chelate type.

(11) fuel cell of above-mentioned (10), wherein, above-mentioned metal complex has the complex structure of N4 chelate type, and the N intratomic of central metal institute combination is the imines type more than at least two.

(12) fuel cell of above-mentioned (10) or (11), it is characterized in that the O-O bond length of the oxygen molecule that combines with the complex compound central metal in the metal complex that above-mentioned metal complex calculates with the B3LYP Density functional method of counting and the adsorption structure of oxygen molecule is from for more than the 0.131nm.

(13) fuel cell of above-mentioned (12), wherein, the metal complex of above-mentioned N4 chelate type is one or both in following general formula 1 or the general formula 2.

General formula 1

(wherein, M is a metallic atom, R ¹～R ¹⁰Be hydrogen or substituting group.)

General formula 2

(wherein, M is a metallic atom, R ¹¹～R ²⁴Be hydrogen or substituting group.)

(14) fuel cell of any one in above-mentioned (10)～(13), wherein, the complex compound central metal of above-mentioned metal complex is more than one the metal that is selected from the transition metal of periodic table V family, VI family, VII family or group VIII.

(15) fuel cell of any one in above-mentioned (10)～(14) is characterized in that, as above-mentioned catalyst component, also contains noble metal.

(16) gas diffusion electrode for fuel cell, it is characterized in that, be made of following part: the catalyst layer of the negative electrode at least of any one fuel cell in above-mentioned (1)～(15), what form at the opposition side of the face that contacts with the proton-conductive electrolyte film of this catalyst layer is the microporous layers of principal component and what form on this microporous layers is the gaseous diffusion fibrage of principal component with the fibrous carbon material with the carbon black, wherein, the carbon black of this microporous layers is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity.

(17) gas diffusion electrode for fuel cell of above-mentioned (16) is characterized in that, as the DBP oil absorption XmL/100g and the nitrogen adsorption specific surface area Ym of the carbon black of the principal component of above-mentioned microporous layers ²The ratio X/Y of/g is more than 1.

Has excellent properties aspect the gaseous diffusion of the fuel cell that the catalyst layer of stipulating among the present invention is used for negative electrode at least in catalyst layer, electrical conductivity, proton conduction, the moisture management, and, can improve the utilance of catalyst component, reduce the noble metal use amounts such as platinum that are used for catalyst, promptly have the fuel cell that cost degradation and output characteristic improve two specific characters concurrently so can provide.

In addition, according to the present invention, because it is suitable to be used for the characteristic of carbon black of gas diffusion layers, so carry out in to catalyst layer in the sufficient humidification, the evolving path of gas is not easy the obstructions such as water droplet that produced, can show higher output characteristic.

Embodiment

The electrode assembly that contains in the fuel cell of the present invention is made of catalyst layer and gas diffusion layers, catalyst layer is characterised in that, by containing catalyst component, the mixture of material with carbon element and electrolyte constitutes, and material with carbon element by load catalyst component the catalyst carrier material with carbon element and do not have the gaseous diffusion material with carbon element of supported catalyst composition to constitute, gas diffusion layers is characterised in that, constitute by the microporous layers that with the carbon black is principal component in the one side that contacts with catalyst layer, constitute by the gaseous diffusion fibrage that with the fibrous carbon material is principal component in the one side opposite of microporous layers with catalyst layer.

Below, be directed to the structure of catalyst layer of the present invention, the gas-diffusion electrode that has made up gas diffusion layers and catalyst layer is described in detail.

The catalyst layer of fuel cell of the present invention is characterised in that, as the synergy of following three kinds of structures, can significantly bring into play the fuel battery performance through improving.

Promptly, (1) as the inscape of catalyst layer, except load the material with carbon element and electrolyte of catalyst, the also new material with carbon element that does not have supported catalyst that adds, helping gaseous diffusion, when materials such as the circulation of water move, water proofing property by material with carbon element is come " controlling moist environment energetically ", (2) by " the surface texture optimizations of catalyst cupport material with carbon element " such as pores being improved the utilance of catalyst, (3) be suitable for the transition metal complex of N4 chelate structure as catalyst component, and, according to quantum chemistry calculation, with the O-O bond length of the oxygen molecule that combines with the complex compound central metal in the adsorption structure of metal complex and oxygen molecule from optimization, successfully the catalytic activity of the oxygen reduction reaction of metal complex is brought up to the level equal with platinum thus, and cut down the platinum use amount significantly.

Below, to above-mentioned three kinds of structures, be described in detail.

The moist environment of＜control catalyst layer 〉

The kind of the material with carbon element that uses in the catalyst layer that contains in the fuel cell of the present invention so long as usually the material with carbon element that exists with electronic conductivity get final product, have no particular limits, chemical reaction beyond the original desired reaction preferably can not take place or constitute the material of material with carbon element can be because the material that wash-out comes out with contacting of water of cohesion, preferred chemically stable material with carbon element.

In addition, the primary particle size of material with carbon element is preferably below the 1 μ m, can pulverize the back greater than the material with carbon element of 1 μ m and use.If primary particle size surpasses 1 μ m, the possibility of then blocking gas diffusion path and proton conduction path increases, and in addition, it is inhomogeneous that the distribution of the material with carbon element in the catalyst layer is easy to become, so not preferred.

As preferred material with carbon element, prevailing is carbon black, can use carbon compounds such as various crystalline material with carbon element that various raw material carbonizations or graphitization are obtained, graphite material, carbon fiber etc. and their crushed material, carbon nano-fiber, carbon nano-tube etc. in addition.In addition, also can use in the above-mentioned material with carbon element more than two kinds.

Material with carbon element as one of principal component of the catalyst layer that contains in the fuel cell of the present invention can be divided into catalyst carrier material with carbon element and gas diffused carbon material.

By in catalyst layer, containing the material with carbon element that do not have the supported catalyst composition, being the gaseous diffusion material with carbon element, can make the path that gas can spread in the catalyst layer become flourishing, and if anode, hydrogen or be easy in catalyst layer, spread then based on the mist of hydrogen, and if negative electrode, then oxygen or air etc. are easy to spread in catalyst layer, thereby can contact with a large amount of catalyst surfaces.

Therefore, the reaction in the catalyst layer is carried out effectively, be obtained high battery performance.

The catalyst carrier material with carbon element that uses in the catalyst layer of the present invention can load for the effective catalyst component of the kind of gas supplied, so long as the good material with carbon element of electronic conductivity, then without limits to the kind of catalyst component and material with carbon element.

As the example of catalyst component, can list noble metals such as platinum, palladium, ruthenium, gold, rhodium, osmium, iridium, with the complex compound of complex compound, transition metal, transition metal and the organic compound of the complex of these noble metals noble metal of compoundization formation more than two kinds and alloy, noble metal and organic compound or inorganic compound or inorganic compound, metal oxide etc.In addition, also can use material that above-mentioned catalyst component is compounded to form more than two kinds etc.

Example as the catalyst carrier material with carbon element, prevailing is carbon black, can use carbon compounds such as various crystalline material with carbon element that various raw material carbonizations or graphitization are obtained, graphite material, carbon fiber etc. and their crushed material, carbon nano-fiber, carbon nano-tube etc. in addition.In addition, also can use in the above-mentioned material with carbon element more than two kinds.

The preferred content of catalyst carrier material with carbon element in catalyst layer is owing to the kind and content, the kind of catalyst component and the influence of load factor that are subjected to catalyst carrier material with carbon element and gaseous diffusion material with carbon element, so can not carry out specific.If the scope of 5 quality %～80 quality % just can play the effect of fuel cell at least, obtain effect of the present invention.

If enumerate preferred scope, then be 10 quality %～60 quality %.If outside this scope, then, can not become the high fuel cell of efficient with the balance variation of other principal component.For example, if be lower than 5 quality %, then the quantitative change of the catalyst component of load gets very few on the catalyst carrier material with carbon element.In addition, if for example surpass 80 quality %, then the quantitative change of electrolyte get very few because the bang path of proton becomes poor, so still can not become the high battery of efficient.

In addition, the catalyst carrier material with carbon element is that 90% o'clock water vapor adsorption amount is that 50mL/g is when above 25 ℃ and relative humidity, then near the electrolyte the catalyst component can keep suitable moisture state, can prevent the decline of proton-conducting, even so on the catalyst component of negative electrode, not too generate low current density when discharge of water, resistance of proton conductivity can not raise yet, and can keep the desirable state of the battery that acts as a fuel.

In addition, on aforesaid catalyst carrier material with carbon element, because the catalyst component of load is easy to miniaturization usually, even a spot of catalyst component, the reaction table area also can become greatly, so be preferred.Therefore, the catalyst carrier material with carbon element is easy more good more by water-wet, thereby can not limit the higher limit of preferable range that 25 ℃ and relative humidity are 90% o'clock water vapor adsorption amount.

But, as long as material with carbon element is used for catalyst carrier, then just should there be boundary as amount that can the adsorbed water steam, if so enumerate 25 ℃ and relative humidity potentially is the limit value in fact of 90% o'clock water vapor adsorption amount, then can list the about 1500mL/g that obtains by active carbon with high specific surface area.

Relative humidity is 90% o'clock water vapor adsorption amount when being lower than 50mL/g, and near the electrolyte the catalyst component is easy to become dry, and proton-conducting is easy to descend, so not preferred.In addition, it is big that the particle diameter of the catalyst component of load also is easy to become usually, thus need a large amount of catalyst components in order to bring into play sufficient battery performance, so not preferred.

As 25 ℃ of index of the present invention and relative humidity is that 90% o'clock water vapor adsorption amount is that the steam volume that the steam vapour amount that adsorbs in the every 1g material with carbon element that will be placed under 25 ℃ of environment is scaled standard state is represented.25 ℃ and relative humidity is that the measurement of 90% o'clock water vapor adsorption amount can use commercially available water vapor adsorption measuring device to measure.Perhaps, also dried gaseous diffusion material with carbon element can be left standstill time enough in 25 ℃, the constant temperature and humidity cabinet of relative humidity 90%, measure by mass change.

The gaseous diffusion material with carbon element that is used for catalyst layer of the present invention is in the content of the catalyst layer scope of 5 quality %～50 quality % more preferably.If be lower than 5 quality %, abundant enlargement gas the evolving path then contains the effect that the gaseous diffusion material with carbon element brought and becomes indeterminate.When surpassing 50 quality %, because the proton conduction path becomes poor, it is big that the IR loss becomes, so battery performance descends.

Although also depend on the kind and the form of the material with carbon element of use, most preferably be 10 quality %～35 quality %.If in this scope, then can not damage proton conduction path and electrical conductance path and make gas diffusion path become flourishing.

Especially, the gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is 100mL/g when following 25 ℃ and relative humidity, and then above-mentioned effect is remarkable.

If the gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity, the water slug gas diffusion path that generates in the time of then can further suppressing because of heavy-current discharge can take out electric current under stable voltage.If surpass 100mL/g, then when current discharge, can in catalyst layer, be detained cohesion water, be easy to cut off gas diffusion path, it is unstable that the voltage behavior becomes easily.

In order to obtain higher effect, use the gaseous diffusion material with carbon element of hydrability in proper range on surface.Specifically, can be chosen in 25 ℃ and relative humidity is that 90% o'clock water vapor adsorption amount is that the material with carbon element of 1mL/g～50mL/g is as the gaseous diffusion material with carbon element.

If in this scope, even then when the few low current density of the inner water that generates of negative electrode discharges, can prevent that also the electrolyte in the negative electrode from becoming dry, keep suitable moisture state, and, when heavy-current discharge, also can be discharged to the inner water that generates of catalyst layer outside the catalyst layer effectively, guarantee the evolving path of gas, so, can in whole zone, obtain the high battery of efficient no matter be by what loading condiction of underload to high load capacity.

In addition, be the material with carbon element of 1mL/g～50mL/g if 25 ℃ and relative humidity are 90% o'clock water vapor adsorption amount, then also material with carbon element more than two kinds can be mixed as the gaseous diffusion material with carbon element.

25 ℃ and relative humidity is that 90% o'clock water vapor adsorption amount is when being lower than 1mL/g, it is strong that water proofing property became, especially the electrolyte that coexists in catalyst layer when low current discharges is difficult to the moisture state that keeps suitable, proton-conducting might descend, so reduce the effect that adds the gaseous diffusion material with carbon element sometimes.

25 ℃ and relative humidity is that 90% o'clock water vapor adsorption amount is when surpassing 50mL/g, might be when continuously taking out big electric current etc., the inner water that generates of catalyst layer has little time to discharge, thereby cuts off gas diffusion path, so reduce the effect that adds the gaseous diffusion material with carbon element sometimes.

The material with carbon element that contains in the fuel cell of the present invention, be that the control of the hydrability of gaseous diffusion material with carbon element and catalyst carrier material with carbon element can be by coming the water vapor adsorption amount to select to be achieved as index from the material with carbon element of common existence.Perhaps, if have under the situation of material with carbon element of the water vapor adsorption amount littler than suitable scope, also can perhaps be exposed under the oxidizing atmosphere environment, make the water vapor adsorption amount increase to suitable scope by material with carbon element is handled carbon material surface with acid or alkali etc.

Though without limits, for example can or impregnated in the aqueous hydrogen peroxide solution, or in ammonia flow, heat-treat, or impregnated in the sodium hydrate aqueous solution of heating by in the red fuming nitric acid (RFNA) of heating, handling, or at dilution oxygen or dilution NO or NO ₂In carry out heat treated, increase the water vapor adsorption amount.

On the contrary, when the water vapor adsorption amount is too much, can make the water vapor adsorption amount be reduced to suitable scope by under inert atmosphere, calcining.Though without limits, can under atmosphere such as argon, nitrogen, helium, vacuum, carry out heat treated, reduce the water vapor adsorption amount thus.

In the catalyst layer that in fuel cell of the present invention, contains,,, then they are had no particular limits as long as can bring into play effect no matter what the kind of employed dielectric film, electrolyte and form be.

The fuel cell that the catalyst layer that contains in the fuel cell of the present invention is brought into play effect most is preferred for the fuel cell of working under the water capacity easily condenses upon condition in the catalyst layer, polymer electrolyte fuel cell etc. for example, but the effect of catalyst layer of the present invention and do not rely on electrolytical kind and form, working temperature etc.

The electrolyte that uses in dielectric film that uses in the fuel cell of the present invention and the catalyst layer can list the macromolecule of having introduced phosphate, sulfonic group etc., perfluorinated sulfonic acid polymer and introduced polymer of benzene sulfonic acid etc. for example, but be not limited to these macromolecules, can be used for using the fuel cell of mineral-type, inorganic-proton-conductive electrolyte films such as organic mixing class.

If enumerate specially suitable operating temperature range, the fuel cell of preferably in the scope of normal temperature～150 ℃, working then.

In addition, catalyst carrier material with carbon element and the electrolyte mass ratio in catalyst layer is preferably 1/5～5/1.The catalyst carrier material with carbon element was less than 1/5 o'clock, catalyst surface is excessively covered by electrolyte, the area that reacting gas can contact with catalyst component diminishes, so it is not preferred, in addition, the catalyst carrier material with carbon element that contains was greater than 5/1 o'clock, and it is poor that the network of electrolyte becomes, proton-conducting descends, so not preferred.

The manufacture method of the catalyst layer that contains in the fuel cell of the present invention has no particular limits.For example,,, add entry and organic solvent as required, make printing ink to wherein adding dissolving or having disperseed electrolytical solution as perfluorinated sulfonic acid polymer with catalyst carrier material with carbon element and gas diffused carbon material mixing.Can be membranaceous with this ink setting, as catalyst layer.

But, to work effectively in order to make the catalyst layer that contains in the fuel cell of the present invention, the preferred selection makes electrolyte not contact the method made from the gaseous diffusion carbon material surface as far as possible.Particularly preferred catalyst layer manufacture method is as described below.

A) with load the catalyst carrier material with carbon element of catalyst and electrolyte pulverize mixing in the good solvent of electrolyte after, the poor solvent that adds electrolyte, make electrolyte and load the catalyst carrier material with carbon element of catalyst mix cohesion and obtain A liquid, to not have the gaseous diffusion material with carbon element of supported catalyst composition in the poor solvent of electrolyte, to pulverize and obtain B liquid, A liquid and the mixing of B liquid are obtained C liquid, C liquid drying is the membranaceous catalyst layer that forms.

In this method, if with load the catalyst carrier material with carbon element of catalyst in the good solvent of electrolyte, pulverize mixing with electrolyte, then the load of big agglomerate the catalyst carrier material with carbon element of catalyst pulverized and be fine agglomerate, at its near surface, electrolyte becomes the state that dissolving exists.

If to the poor solvent that wherein adds electrolyte, make the electrolyte cohesion, then load the catalyst carrier material with carbon element of catalyst and electrolyte particle can produce and mix cohesion, thereby on electrolyte the has been fixed on load catalyst carrier material with carbon element of catalyst.

In addition, if in this solution, add fine gaseous diffusion material with carbon element, then because on the electrolyte catalyst carrier material with carbon element of catalyst that has been fixed on load, so the gaseous diffusion carbon material surface is not easy to be covered by electrolyte, can effectively utilize the surperficial original surface texture that has of gaseous diffusion material with carbon element.

When the gaseous diffusion material with carbon element of surperficial hydrability had been controlled in use, this method was effective especially.

B) with load catalyst the catalyst carrier material with carbon element and the trace electrolyte in the good solvent of electrolyte, pulverize mixing after, make its curing by drying, to the poor solvent that wherein adds electrolyte, after the solid matter pulverizing, splash into the solution that is dissolved with electrolyte again and obtain A liquid, to not have the gaseous diffusion material with carbon element of supported catalyst composition in the poor solvent of electrolyte, to pulverize and obtain B liquid, A liquid and B liquid are mixed the C liquid that obtains, C liquid drying is the membranaceous catalyst layer that forms.

In this method, if with load the catalyst carrier material with carbon element of catalyst pulverize in the good solvent of electrolyte with the electrolyte of trace and carry out drying after mixing, then Wei Liang electrolyte is with on the membranaceous catalyst carrier carbon material surface of catalyst that has been fixed on load.

If it is pulverized, then can under the state on the electrolyte catalyst carrier material with carbon element of catalyst that has been fixed on load, carry out micronize in the poor solvent of electrolyte.

In addition, splash into required enough electrolyte solutions in this solution, electrolyte generates the dispersion liquid that condenses with the catalyst carrier material with carbon element that is fixed with electrolyte seldom.

If to wherein adding fine gaseous diffusion material with carbon element, then with A) method identical, since electrolyte in load fixing or cohesion on the catalyst carrier carbon material surface of catalyst, so the gaseous diffusion carbon material surface is not easy to be covered by electrolyte, can effectively utilize the surperficial original surface texture that has of gaseous diffusion material with carbon element.

This method has been controlled under the situation of gaseous diffusion material with carbon element of surperficial hydrability also effective especially in use.

The good solvent of the electrolyte that uses in above-mentioned catalyst layer manufacture method is meant the solvent of the employed electrolyte of solubilized in fact, owing to depend on the kind and the molecular weight of electrolyte, so can not limit.

If enumerate object lesson, the good solvent of the perfluorinated sulfonic acid polymer that contains in 5%Nafion (the Na Off ィオ Application) solution as commercially available ア Le De リッチ system can list methyl alcohol, ethanol, isopropyl alcohol etc.

In addition, the poor solvent of the electrolyte that in above-mentioned preferred catalyst layer manufacture method, uses, be meant the solvent that does not dissolve employed electrolyte in fact, because solvent different and different according to the kind of electrolyte and molecular weight, so can not carry out specific.

For example, if enumerate the poor solvent of the perfluorinated sulfonic acid polymer that contains in the 5%Nafion solution of commercially available ア Le De リッチ system, can list hexane, toluene, benzene, ethyl acetate, butyl acetate etc.

As at above-mentioned A) or preferred catalyst layer manufacturing method thereof B) in pulverize or pulverize the method for mixing, as long as can will become the catalyst carrier material with carbon element and the gas diffused carbon material of big agglomerate pulverizes, can reach the purpose of pulverizing to the following agglomerate of at least 1 μ m, then this method just without limits.

As general method, if enumerate example, can list and utilize hyperacoustic method, use ball mill and bead etc. to carry out the method etc. of mechanical crushing.

When being membranaceous with ink setting, can be suitable for the method for common proposition, be not particularly limited, for example can list, on as the carbon paper of gas diffusion layers after coating and the drying, on the such dielectric film of perfluorinated sulfonic acid polymer, carry out the method for crimping by hot pressing etc.; After coating on the such dielectric film of perfluorinated sulfonic acid polymer, carry out dry method; On ptfe sheet etc., after the coating one time, carry out drying, it is transferred to method on the such dielectric film of perfluorinated sulfonic acid polymer etc. by hot pressing etc.

＜suitably use active carbon as the catalyst carrier material with carbon element 〉

Present inventors etc. have carried out wholwe-hearted research, found that as the catalyst carrier material with carbon element, have controlled the active carbon of surface texture and can bring into play excellent characteristic, thereby finished the present invention.

The essential effect that active carbon is used for catalyst carrier can be speculated as following 2 points.

1, introduces the effect of the adsorption site of supported catalyst metal particle to high-density at carrier surface.

2, improve the compatibility of carrier surface and polyelectrolyte and increase the effect of the adsorbance of polyelectrolyte.

As follows by the concrete performance improvement expectation that above-mentioned effect produces.That is,, can expect the micronize of catalyst metals of load and the high density load of catalyst metals particulate by increasing above-mentioned adsorption site at the 1st.Can infer that adsorption site is the pore of activated carbon surface.

The precursor compound of input catalyst metals (for example in the water that is being dispersed with carbon carrier, chloroplatinic acid) aqueous solution and reducing agent are (for example, potassium borohydride etc.) aqueous solution and when carrying out the reduction of precursor and the load on carrier simultaneously, the particle size of carrying metal microparticles is by the competitive reaction decision to the absorption probability and the particle growth of carrier.

What determine this absorption probability is the superficial density of the adsorption site of carrier surface, because high superficial density, the catalyst metals particulate that is reduced can be adsorbed with the state of littler particle size.

In addition, if the superficial density height of adsorption site, then when supported catalyst metal particle to high-density, can be on the catalyst particles that has adsorbed, adsorb other catalyst particles again and be integrated, thereby reduce the probability of thickization of particle, result, the catalyst metals particulate that load to high-density is fine.

By catalyst metals is carried out micronize; can increase the area of catalyst metals per unit mass; its result; with regard to the same catalyst metal quality; then because effectively catalyst reaction area increase; so the output voltage of electrode improves, perhaps, can reduce and be used to obtain identical output voltage and essential catalyst metals quality.

In addition, if supported catalyst metal particle to high-density promptly, can improve (quality) load factor of catalyst metals, with regard to identical catalyst metals quality, can make the correspondingly attenuation of thickness of catalyst layer.

The filming of catalyst layer is concerning the short distance ionization of gas diffusion path,, is concerning the minimizing of material moving resistance that is, and its result can reduce the material moving resistance in the electrode reaction.

On the other hand,, then can improve the catalyst metals particulate and the contacted ratio of electrolyte macromolecule of load on the carrier, that is, can increase the effective surface area of catalytic reaction if can improve the above-mentioned carrier surface and the compatibility of polyelectrolyte at the 2nd.

Therefore, with regard to identical catalyst metals quality,,, perhaps, can reduce and be used to obtain identical output voltage and essential catalyst metals quality so the output voltage of electrode improves because effectively the catalyst reaction area increases.

In order to show above-mentioned catalyst carrier effect, as the index of the surface texture that characterizes optimal active carbon, present inventor etc. have carried out wholwe-hearted research, and the result judges that following index is the most suitable.That is, optimal index has specific area (total specific area), is specific area, the average diameter of micropore, oxygen content, the DBP oil absorption of the micropore of the hole definition below the 2nm with the diameter.

Basically, for supported catalyst metal particle to high-density on carbon carrier, require to a certain degree above bigger serface.If it is represented particularly, be SBET 〉=1500m ²/ g.Wherein, SBET is the specific area value of being obtained by the measurement of the absorption isotherm of nitrogen under liquid nitrogen temperature with the BET method.

SBET is lower than 1500m ²During/g, be difficult to meet common high performance catalyst desired " the above diameter of load 50 quality % is the following catalyst metals particulate of 3nm ".Be more preferably SBET 〉=1600m ²/ g.The upper limit of specific area is not particularly limited, and as the specific area of material with carbon element, reality is 4000m ²Below/the g.

It is generally acknowledged that the minimum grain size the when specific activity that can keep catalytic activity that the reguline metal shows and unit mass is maximum is the diameter of 1～3nm, the adsorption site that can infer the catalyst metals of such size is a micropore, so the major part of specific area must come from micropore.

Its concrete manifestation is as follows, and promptly diameter is the long-pending Smicro (m of the following micropore surface of 2nm ²/ g) with respect to total pore area Stotal (m ²/ g) ratio is Smicro/Stotal 〉=0.5.More preferably Smicro/Stotal 〉=0.6, further preferably Smicro/Stotal 〉=0.7.

In addition, because the surface area of micropore can not exceed total surface area, so Smicro/Stotal≤1.Smicro/Stotal＜0.5 o'clock, the density of adsorption site is low, is not suitable for the micronize of catalyst and the high density load of catalyst metals particulate.

The catalyst metals particulate that wants to form load can need the diameter of the pore of regulation active carbon with 1 above-mentioned～3nm by the adsorption site of high-efficient carrier.The result of wholwe-hearted research is that the average diameter of micropore is preferably 0.7nm～1.5nm, more preferably 0.8nm～1.4nm.Because the aperture becomes too small when being lower than 0.7nm, thus the function of conduct can be damaged to the adsorption site of the catalyst metals particulate of 1～3nm, can not the supported catalyst metal particle.

In addition, the micropore with regard to the average diameter that surpasses 1.5nm because the catalyst metals particulate is embedded in the pore, has reduced to reacting effective surface area, so be not suitable for the present invention.

In addition, specific area (total specific area), be that the specific area of the micropore of the hole definition below the 2nm, the average diameter of micropore all are to be calculated in the absorption isotherm under the liquid nitrogen temperature by nitrogen with the diameter.The average diameter of micropore is used the value that is calculated by 2 * Vmicro/Smicro.

This is when the pore of supposition slit-shaped the slit separation distance to be calculated as pore diameter.Smicro, Stotal, Vmicro use by t-curve and resolve the value that (Japanization association compiles, colloid chemistry I, the same people of Co., Ltd.'s Tokyo chemistry, nineteen ninety-five distribution) calculates.

Usually, active carbon is introduced oxygen the pore surface of active carbon according to its manufacture method with various chemical forms.For example carboxyl, hydroxyl, quinoid oxygen, lactonic ring, cyclic ether etc.

Present inventors etc. attentively study, if the result clear and definite excess oxygen content, then because the contact resistance between catalyst particle becomes big, so the Ohmic resistance when forming catalyst layer increases, output voltage descends thus.

Optimal oxygen content scope is below the 5 quality %, more preferably below the 4 quality %.When the oxygen content of active carbon surpasses 5 quality %, because life of catalyst decline, so can not be applicable to the present invention.

The lower limit of oxygen content is not particularly limited, even contain aerobic hardly, also can show good specificity of catalyst.The kind that contains the oxygen functional group is not particularly limited.

The control of the control by making up above-mentioned oxygen content and the micro-pore diameter of activated carbon surface, the so-called catalyst degradation that can suppress to produce along with fuel cell running, this also is the bigger advantage that active carbon of the present invention is used for the catalyst carrier material with carbon element.

Though it is not clear to suppress the mechanism of deterioration, but can infer it is because the interaction of the edge carbon of the pore inwall of formation active carbon and catalyst metals particulate is stronger than the interaction of common carbon carrier and catalyst particles, thereby improved the electronic state of catalyst metals particulate, the result can suppress to go out metal ingredient from the microparticle surfaces wash-out, and it is permanent that catalyst life becomes.

The active carbon of the present invention's regulation is used for carrier, even if obtained the miniaturization of above-mentioned catalyst metals particulate and densification and with the raising of the affinity of polyelectrolyte, but want to make the electrode of the desired characteristic of this catalyst as solid macromolecular electrolyte type fuel cell showed, must make its have gas electrode the characteristic that should possess be gas diffusibility, that is to say, must make porous matter electrode.

As the rerum natura of the powder of above-mentioned purpose, what stipulate among the present invention is the DBP oil absorption.The DBP oil absorption is on one side to carry out the carbon of ormal weight drying mixing, drip dibutyl phthalate (DBP) on one side, the relation of investigating dripping quantity and mixing torque obtains, carbon is moistening by DBP gradually, all touch DBP between all powder, the DBP dripping quantity when mixing torque is risen is defined as the DBP oil absorption.

That is, when the DBP oil absorption is equivalent to the powder particle cohesion, the mean value of the amount of liquid that each powder particle can hold.Under the situation of active carbon, because the pore from particle surface towards inside helps the absorption of liquid, so with respect to the interparticle volume that holds, can be observed the big slightly DBP oil absorption corresponding to pore volume, but, can become the cardinal principle yardstick of inter-particle voids as first approximation.

When with active carbon of the present invention suitably when the carrier, found that of wholwe-hearted research, the DBP oil absorption be 30mL/100g above, be preferably the above active carbon of 50mL/100g and can bring into play excellent electrode characteristic.The DBP oil absorption is 30mL/100g when following, and gas diffusion velocity is unable to catch up with electrode reaction, its result, and output voltage can not be applicable to the present invention owing to gas diffusion resistance descends.

In addition, when the DBP oil absorption surpasses 1000mL/100g,, become blocked up so be used to the thickness of electrode of the catalyst metals amount that obtains to stipulate because the bulk density of electrode becomes too small, its result, the gas diffusion resistance in the electrode increases, and output voltage descends.

Under the situation of secondary aggregate, preferred primary particle satisfies the condition of above-mentioned shape of particle.

(shape of particle of active carbon)

As long as the shape of active carbon of the present invention satisfies These parameters, just be not particularly limited.If enumerate, also can be the fiber shape of fine shape of particle, fine diameter or the secondary aggregate that combines fine particle.

Under the situation of the active carbon of shape of particle, will specify optimal scope as particle size.Present inventors etc. attentively study, and the result judges that specifically, the average grain diameter of 10nm～1 μ m is suitable for the present invention.20nm～800nm more preferably.

With regard to the diameter particle also littler than 10nm, the pore of introducing the following diameter of 2nm in fact is very difficult.In addition, surpass the particle of 1 μ m, because the surface area of carrier per unit mass is too small, so supported catalyst metal particle to high-density with regard to diameter.

At active carbon is under the situation of fibrous form, preferably uses with the powder shape that fiber is pulverized.The diameter of fiber equals the diameter of particle situation, and the average grain diameter of clear and definite 10nm～1 μ m is suitable for the present invention.20nm～500nm more preferably.

In addition, when fiber is pulverized, can be with length-width ratio (fiber length/fibre diameter) below 100, more preferably the powder below 50 is fine is applicable to the present invention.When length-width ratio surpassed 100, the bulk density of electrode became too small, and the thickness that is used to obtain the catalyst layer of necessary platinum amount becomes blocked up, thereby causes electrode reaction inhomogeneous, decreased performance.

(manufacture method of active carbon and carbon raw material)

The active carbon of stipulating among the present invention does not limit its manufacture method, carbon raw material so long as satisfy the just passable of set quota of the present invention.

If enumerate the manufacture method of active carbon, then, can be suitable for the method for in material with carbon element, introducing pore by under 600 ℃～1200 ℃ temperature, handling a few hours in the inert atmosphere that in inert gas, contains steam, carbon dioxide etc. as activating treatment method; Perhaps, alkali-metal hydroxide, carbonate are mixed with the carbon raw material powder end as activating treatment agent, in inert atmosphere, under 500 ℃～1100 ℃ temperature, handle a few hours, in material with carbon element, introduce the method for pore thus.

The carbon raw material of active carbon of the present invention has no particular limits.If enumerate the carbon raw material particularly, then can suit to use petroleum-type coke, coal class coke, phenolic resins, furane resins etc.

The surface texture of＜catalyst carrier material with carbon element and the optimization of stereochemical structure 〉

Present inventors etc. attentively study, and found that as the catalyst carrier material with carbon element, by the control surface structure and control the stereochemical structure of material with carbon element, can make it show excellent catalyst performance.

Specifically, diameter is that the following micropore volume of 2nm is preferably more than the 0.1mL/g, more preferably more than the 0.3mL/g.This is because the atomic thin following pore of 2nm can be used as the adsorption site of fine particle of noble metal and works, and is the necessary condition of enhancement of dispersion of catalyst metals particulate.

If pore volume is lower than 0.1mL/g, then because the decline of the surface density of the adsorption site of the catalyst metals particulate of catalyst carrier carbon material surface, so supported catalyst metal particle to high-density, and, because the catalyst metals particulate is easy to produce cohesion, so that the particle diameter of catalyst metals can become is big.

Do not have the special upper limit for the pore volume below the 2nm, in fact be generally below the 2mL/g, be difficult to obtain to surpass the material with carbon element of 2mL/g.As second function of the micropore below the 2nm, can list the effect of the compatibility of raising and electrolyte.

If can improve the compatibility of carrier surface and polyelectrolyte, just can improve the ratio that contacts between the catalyst metals particulate of load on the carrier and the electrolyte macromolecule, that is, can increase the effective surface area of catalyst reaction.

Thus, with regard to identical catalyst metals quality,,, perhaps, can reduce and be used to obtain identical output voltage and essential catalyst metals quality so the output voltage of electrode improves because effectively the catalyst reaction area increases.

Present inventors etc. attentively study, and found that, as the concrete numerical value of the full contact of electrolyte and catalyst carrier material with carbon element being brought up to the degree that can improve output voltage, are limited to 0.1mL/g under the volume of the micropore that 2nm is following.When the volume of micropore is lower than 0.1mL/g, can't see the substantial improvement of output voltage.

In order to make the catalyst metals particulate carry out even high dispersive with the particle diameter of about 2nm, the surface area of carrier must be just big originally.Present inventors etc. attentively study, and found that, the specific area that the catalyst carrier material with carbon element that contains in catalyst layer utilizes the BET method to obtain is preferably 500m ²More than/the g, 800m more preferably ²More than/the g.The upper limit of contrast table area is not particularly limited, but in fact the upper limit is about 4000m ²/ g, and be difficult to obtain surpass the material with carbon element of this value.

Be used for gaseous diffusion and remove the network that generates water by making structure (structure) become flourishing, can generating, also be not easy to cause overflow when taking out high electric current.Therefore, the DBP oil absorption of catalyst carrier material with carbon element is preferably more than the 300mL/100g, more preferably more than the 400mL/100g.

But, if the DBP oil absorption surpasses 1000mL/100g,, become blocked up so be used to the thickness of electrode of the catalyst metals amount that obtains to stipulate then because the bulk density of electrode becomes too small, its result, the gas diffusion resistance in the electrode increases, and output voltage descends.

(kind of catalyst metals)

The kind of the catalyst component that the present invention is used has no particular limits.

Can list noble metals such as platinum, palladium, ruthenium, gold, rhodium, osmium, iridium for example, with the complex compound of complex compound, transition metal, transition metal and the organic compound of the complex of these noble metals noble metal of compoundization formation more than two kinds and alloy, noble metal and organic compound or inorganic compound or inorganic compound, metal oxide etc.

In addition, also can use material that above-mentioned catalyst component is compounded to form more than two kinds etc.

(load factor)

The load factor of catalyst component on carrier has no particular limits, and is preferably 1 quality %～90 quality %.When being lower than 1 quality %, the thickness that is used to obtain the catalyst layer of practical required output voltage becomes blocked up, so that overvoltage becomes is big.

In addition, just surpass the load factor of 90 quality %, not only being difficult to make catalyst component to carry out differential substantially looses, and the density of the catalyst component in the catalyst layer becomes too high, the a large amount of shipwrecks that generate when the load running of high current density are in being removed by the gaseous diffusion material with carbon element, thereby bring obstacle for stable fuel cell running.

Wherein, so-called load factor is a value of representing to remove with the gross mass of catalyst component and carrier components the quality gained of catalyst component with percentage.

(carrying method of catalyst metals particulate)

The catalyst carrier material with carbon element of stipulating among the present invention is micronize and the high density load that realizes catalyst metals by its highdensity adsorption site, and the carrying method of catalyst metals particulate is had no particular limits.

If enumerate the carrying method of catalyst metals particularly, then can in suitable medium, mix reducing agent and chloroplatinic acid, generate the colloid of platinum particulate.For the stabilisation of colloid, for example, also can in system, add colloid protective agent of macromolecules such as polyvinyl alcohol etc.

In the platinum particulate colloid of making like this, add as the material with carbon element of carrier and stir, the platinum colloid is adsorbed on the carrier.

In addition, also can make platinum particle loaded on active carbon by behind the chloroplatinic acid of load on the material with carbon element, in hydrogen atmosphere, heat-treating as the platinum precursor.

＜metal complex catalyst 〉

Among the present invention, except " moist environment of control catalyst layer ", " structure of control carrier carbon material ", help to reduce the use amount of noble metal catalyst composition, promptly help the technology of cutting down cost to make catalyst component contain the technology of the metal complex of N4 chelate type in addition.

In fuel cell, particularly polymer electrolyte fuel cell, require catalyst under highly acid electrolyte environment, to show catalytic action, so be chemical stability under sour environment as the necessary key element of catalyst.

In the active high various metal complexs of oxygen reduction reaction, the result of wholwe-hearted research such as present inventor is that the metal complex with N4 chelate structure has the highest chemical stability, goes for the present invention.

Under the situation of the cyclic compound complex compound beyond the N4 chelate structure, even initial catalytic activity height, still along with the continuous running of fuel cell, the metal ingredient wash-out at complex compound center comes out, its result, and activity descends as time goes by.

More preferably, have the N4 chelate structure, and the N intratomic that combines with central metal is the metal complex of imines type more than at least two.

When adopting imines type key, the chemical stability of central metal composition improves more, is suitable for the present invention.

In the metal complex that replaces platinum of the present invention, importantly following in essence 3 points:

(a) use the independent high metal complex of catalytic activity,

(b) metal complex and noble metal are coexisted and show catalytic action,

(c), make catalyst cupport on material with carbon element as carrier in order to show above-mentioned catalyst function fully.

The oxygen reduction reaction that uses metal complex to carry out is to be adsorbed on the metallic atom that is positioned at the metal complex center from oxygen molecule to begin.Be to obtain stable adsorbed state under the situation of transition metal when the center metal, be particularly suitable for the present invention.

The reason of preferred transition metal is, because can produce electric charge from the one-tenth key track of oxygen molecule to the empty s track of the transition metal atoms of adsorption site simultaneously moves (donation) and the electric charge from the d track of transition metal atoms to the antibonding track of oxygen molecule and moves (backdonation) (holt is virtue for a long time, the mountain pass gram, the surface, Vol.23, p.311 (1985)).

The result of wholwe-hearted research such as present inventor judges, even in transition metal, and the transition metal of also special preferred cycle table the V family, VI family, VII family or group VIII.

Its reason may not be clear, but from stability as the N4 chelate complex compound of transition metal, need metallic atom to take divalent as stable status, in addition, in the oxygen reduction reaction process, need metallic element to the high oxidation state, promptly, high price number state transition more than 3 valencys from these two conditions, can infer that the transition metal of periodic table V family, VI family, VII family or group VIII can be brought into play excellent characteristic.

Want to make metal complex to have high hydrogen reduction activity, in above-mentioned two kinds of electric charges move, also particularly importantly produce the easy degree of backdonation.That is, this is because if the electron density of oxygen molecule increases, and then the compatibility to proton increases, and, because electronics flows into the antibonding track of oxygen molecule, so the combination between oxygen atom dies down, thereby, also be easy to cause 4 electronic reduction reactions along with the fracture of O-O key.

Therefore, by calculate as the O-O bond length of the oxygen molecule of the index of the degree of the backdonation of expression from the metallic atom to the oxygen molecule from, can infer the activity of oxygen reduction reaction.These calculating can be used the molecular orbital method of non-experience and Density functional to count computational methods such as method to carry out, but from calculating than being easier to, and the viewpoint that can obtain high computational accuracy is set out, effectively Density functional is counted method, count method as this Density functional, can adopt with the B3LYP method is the whole bag of tricks of representative.

Therefore, present inventor waits the result of calculation studied the B3LYP method and actual catalytic activity whether correlation is arranged.All calculate and use the Gaussian98 program to carry out.The basic function that uses is 6-31G basic function for typical element, for metallic element is at " gaussian basis setsfor molecular calculations ", (14s8p5d)/[5s3p2d] of record among the S.Hujinaga (eds.), Elsevier (1984).

At first, calculate cobalt (II) complex compound (being abbreviated as CoDTAA), 5 of dibenzo four azepine annulenes with the B3LYP method, 10,15, cobalt (II) complex compound (being abbreviated as CoTMPP), 5 of 20-four-(4-methoxyphenyl) porphyrins, 10,15, cobalt (II) complex compound (being abbreviated as CoPc) of the cobalt of 20-tetraphenylporphyrin (II) complex compound (being abbreviated as CoTPP), phthalocyanine and the adsorption structure of oxygen molecule.

The result can judge that their O-O bond length is from being respectively 0.1305nm, 0.1288nm, 0.1287nm, 0.1254nm.

In addition, CoTMPP, CoTPP, CoPc are loaded on the carbon black (the system ケッチェ of ライオ Application (strain) society Application Block ラッ Network EC600JD), under the situation of not heat-treating, use rotating disk electrode (r.d.e), measure electric current-voltage characteristic.If the current potential (saturated calomel electrode (SCE) standard) during half current value of comparison saturation current value, then they are respectively 0.119V, 0.083V, 0.075V.

In addition, according to document (H.Jahnke et al., Top.Corr.Chem., Vol.1, p.133 (1976)), reported that CoDTAA is active also higher than CoTMPP.Therefore, according to above research, can judge and calculate the O-O bond length obtain from having correlation with the hydrogen reduction catalytic activity.

Therefore, present inventor etc. also the O-O bond length by calculating the adsorb oxygen molecule from, the structure of the metal complex of hydrogen reduction catalytic activity excellence has been carried out various researchs.Its result, for metal complex with following two chemical formulations, O-O bond length in the oxygen adsorption structure separates and is not calculated as 0.1320nm, 0.1316nm, any all situations than CoDTAA are also long, thereby the Macrocyclic compound complex compound that can judge following two chemical formulas has the above catalytic activity of CoDTAA.

In addition, the central metal atom of metal complex moves to the high oxidation state when hydrogen reduction, recovers the catalyst function of next reaction time in order to make it, central metal atom need be reduced to the suboxides state.This reduction reaction is easy more carrying out when the electrophilic of complex compound dentate is strong more.

On the contrary, the O-O bond length of above-mentioned adsorb oxygen molecule is from existing the backdonation from the metallic atom to the oxygen molecule strong more, that is, dentate give the strong more trend that then becomes long more of electronics.

If consider above viewpoint, then when the O-O of adsorb oxygen molecule bond length when long, reduction reaction that might the central metal difficulty that becomes is so above-mentioned O-O bond length is from being preferably below the 0.136nm.

As the dentate of the metal complex that is suitable among the present invention, can list dentate with general formula 1, general formula 2 expressions.Wherein, the substituting group of representing with R1～R24 is hydrogen or substituting group, as substituting group, can be the same or different, and can list replacement and unsubstituted alkyl, aryl etc.

As alkyl, can list methyl, ethyl, n-pro-pyl, isopropyl, methoxyl group, ethyoxyl etc.Alkyl also can be that two alkyl form ring-types, for example, can list that alkyl substituent with R1 and R2 carries out closed loop and the compound that formed cyclohexyl ring.

As concrete dentate, can list 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclododecane ten four-2,4,6,9,11,13-six alkene, 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclododecane ten four-4,6,11,13-tetraene etc.

As aryl, can list the phenyl of phenyl, alkyl replacement etc.As concrete dentate, can list 6,13-diphenyl-1,4,8,11-tetraazacyclododecane ten four-2,4,6,9,11,13-six alkene etc.

In these dentates, the compound that replaces owing to alkyl is easy to synthesize, so preferred.

In addition, catalytic activity changes because of the difference of transition metal kind.The result that the present inventor attentively studies is, do not depend on the kind of dentate and shows one or both of highly active Co of being or Fe, goes for the present invention.

The load capacity of metal complex of the present invention is preferably below the 2 quality % in the load capacity of metallic element, more preferably below the 1 quality %.If load surpasses 2 quality %, the relative grow of the catalytic action of metal complex then, the increasing degree of the catalytic activity that produces with the coexistence of noble metal diminishes.

In addition, in order to show the effect as catalyst, the load capacity of metal complex is preferably more than the 0.01 quality % in the load capacity of metallic element, more preferably more than the 0.05 quality %.

The composite catalyst that metal complex of the present invention and noble metal coexistence form is the object lesson shown in the embodiment as described later, is based on the catalytic activity experimental fact also higher than each independent catalytic activity of this coexisting state.

Its theoretical explanation is also uncertain, but for example infer, be owing on noble metal, take place in 4 electronic reduction reactions, and then 2 electronic reduction reactions that on metal complex, take place, 2 electronic reduction reactions etc. take place on noble metal again, carry out oxygen reduction reaction by two reduction reaction routes, so compare with independent separately situation, the situation of coexistence can promote catalytic activity.

The noble metal that uses among the present invention is meant ruthenium, rhodium, palladium, osmium, iridium, platinum and with they alloys as principal component.

Consider from the height of catalytic activity, among the present invention, preferably be suitable for ruthenium, rhodium, palladium, osmium, iridium, platinum and they alloys as principal component.

More preferably be suitable for the alloy of platinum as principal component.Specific catalytic activity is low mutually with platinum for other noble metal, improves though can see the catalytic activity that produces with the coexistence of metal complex, and its improvement amplitude is little.

Be preferably below the 50 quality % with the load capacity of the noble metal of metal complex catalyst of the present invention coexistence.If load surpasses 50 quality %, the independent relative grow of catalytic action of noble metal then, the increasing degree of the catalytic activity that produces with the coexistence of metal complex diminishes.

In addition, if also consider the cost of catalyst, then the load capacity of noble metal is more preferably below the 40 quality %.In addition, in order to bring into play the effect as catalyst, the load capacity of noble metal is preferably more than the 1 quality %, more preferably more than the 2 quality %.

In addition, want to bring into play fully the effect of the metal complex catalyst among the present invention, metal complex catalyst is loaded on the material with carbon element.The essence of the catalytic activity of the catalyst of stipulating among the present invention can infer it is the surface of material with carbon element and the interaction that metal complex produces by pi-electron.

Therefore, to make this pi-electron interact to become more to pretend and be target, method of adjustment to catalyst is attentively studied, found that behind area load metal complex that makes carbon dust and noble metal, in non-oxidizing atmosphere, under 500 ℃～1100 ℃ temperature, heat-treat, can prepare highly active catalyst thus.

Wherein, if handle, then produce the oxidation consumption of carbon carrier and metal complex under oxidizing atmosphere, catalyst activity disappears.In addition, when heat-treating under being lower than 700 ℃ temperature, the pi-electron of carbon carrier and metal complex interacts not enough, can not show catalytic activity.On the other hand, when under surpassing 1100 ℃ temperature, heat-treating, because the thermal decomposition of metal complex deposits yields, so catalyst activity disappears.

This method for preparing catalyst only makes metal complex load on situation on the carbon carrier and all effectively same in the complex catalyst system that the coexistence of metal complex and noble metal catalyst forms.

Want to improve the catalytic activity of the coexistence system of metal complex or metal complex and noble metal, preferably the surface area as the material with carbon element of catalyst carrier is bigger.The effect of catalyst carrier can infer and be not only the physical effect that enlarges simple reacting environment, and can come activate is carried out in catalytic action by the interaction to the chemistry of metal complex deposits yields.

As mentioned above, in the catalytic reaction process of metal complex, the recovery of the catalyst function that reduction produced of central metal atom is to move by the electronics that comes from the dentate that combines with the metallic atom chelating to realize.So, make and move to the electronics of metallic atom by dentate that to become easier be the carrier that forms the material with carbon element of huge pi-electron system.

Surface area to the carrier carbon material is attentively studied, specific area (the BET specific area: SBET) be the index that is fit to that the result obtains according to the BET formula evaluation of the adsorption isotherm of nitrogen as can be known.

Its concrete number range is 500m ²More than/the g.Be lower than 500m ²During/g, infer the defective of the carbon wire side concavo-convex, that produce by minute aperture of carbon surface that the catalytic activity make metal complex increases, the quantity not sufficient of marginal portion, can not show the raising of catalytic activity.

On the other hand, if increase surface area to 3000m ²More than/the g, then might form the minute aperture that is deep into carbon inside, because the surface, inside of this minute aperture accounts for the ratio of reacting environment's integral body and uprises, so materials such as oxygen diffusion move the domination full responsiveness, can not form actual catalytic reaction place, catalytic activity is deterioration on the contrary, so not preferred in the present invention.

For the carbon carrier load to high-density of the carrier that makes the coexisting body series catalysts that is used as metal complex or metallic catalyst and noble metal catalyst among the present invention transition metal complex as catalyst, carbon carrier is the fine-particle powder shape preferably.Optimal particle diameter is that average diameter is 10nm～1 μ m.

When having secondary structure as aggregated structure originally as the particle of least unit the carbon black, above-mentioned average diameter is set at the diameter of primary particle.

When average diameter is lower than 10nm, be difficult to the micropore below carrier surface introducing 2nm in fact, if average diameter surpasses 1 μ m, then owing to be used to guarantee the effective surface area ground electrode of catalytic reaction layer thickness is increased, so it is big that the diffusional resistance of gas becomes, the decreased performance of the battery that acts as a fuel.

The structure of＜gas diffusion layers 〉

Among the present invention, important techniques is successfully to draw the performance that catalyst layer had originally to greatest extent by constituting gas-diffusion electrode, and wherein said gas-diffusion electrode has made up the gas diffusion layers of the catalyst layer of suitable high performance.

That is, gas diffusion layers of the present invention is a double-layer structure, and the layer of barrier film side is by constituting with the gaseous diffusion fibrage of fibrous carbon material as principal component, and the layer of catalyst layer side is made of the microporous layers that with the carbon black is principal component.

Selecting with the fibrous carbon material in the barrier film side is because target is to have gas-premeable and electronic conductivity concurrently as the fibrolaminar reason of the gaseous diffusion of principal component.As both forming the large aperture that gas is easy to spread, have the conductive material of good electron again, the fibrous carbon material is the material that is fit to.

Though have no particular limits,, can list the carbon cloth and the carbon paper that constitute by carbon fiber if enumerate preferred example.

Among the present invention, the fibrous carbon material is the fibrolaminar principal component of gaseous diffusion, also can strengthen with adhesives such as macromolecular materials in order to increase mechanical strength, perhaps again can compound second, third composition with using after its carbonization etc.

Moreover, also can be coated on the surface of fibrous carbon material by using fluororesin or surfactant, silane coupling agent etc., use the fibrous carbon material after improving water proofing property.Perhaps, also the fibrous carbon material can be heat-treated under inert atmosphere and improve water proofing property.

As the method for coating, can enumerate and send as an envoy to the fluororesin latex or be dispersed with the liquid of fluororesin of pulverizing or the liquid etc. that contains silane coupling agent contacts with the gaseous diffusion fibrage by coating, dipping, injection etc., and carry out the method etc. of drying.

Under the situation as fluororesin, also can be warming up to after the drying more than the fusing point, by making its fusing or the softening coating homogenizing that makes.

Gaseous diffusion fibrage of the present invention is owing to have the large aperture and rustic, so for as directly with have the catalyst layer contacting structure of fine structure, contact site during with battery combination between gaseous diffusion fibrage and catalyst layer is few, and perhaps the face that catalyst layer is applied extrudes existing disorderly distribution.

These are relevant with the electrical conductivity resistance and the distribution of gas diffusibility and reactivity etc. in the catalyst layer for example, and the result can not bring into play the performance as battery fully.

In order to prevent this problem, between gaseous diffusion fibrage and catalyst layer, microporous layers is set.If both had finer structure, preferably had a physical dimension identical with catalyst layer, be again can not damage the material of gas diffusibility and electronic conductivity and can eliminate the fibrolaminar rustic of gaseous diffusion and be connected with catalyst layer, just can suppress the reaction profile in the catalyst layer, can bring into play battery performance fully.

As microporous layers of the present invention, use carbon black as principal component.First reason of using carbon black is because have identical physical dimension with catalyst layer, has excellent electronic conductivity, possesses suitable surface characteristic according to the difference of kind, thereby can prevent effectively that gas diffusion path is by water slug.

This carbon black can be selected the water vapor adsorption amount as index.Specifically, if carbon black is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity, then for example, the obstruction of the gas diffusion path that the water that generates in the time of can being suppressed at cathode side because of heavy-current discharge causes can be taken out electric current under stable voltage.

If surpass 100mL/g, then cohesion water can be trapped in the microporous layers when current discharge, cuts off gas diffusion path, and it is unstable that the voltage behavior becomes.

In order to obtain higher effect, the water vapor adsorption amount that can be chosen in 25 ℃ and relative humidity and be at 90% o'clock is the carbon black of 1mL/g～50mL/g.

If in this scope, during the low discharging current that then even the water that generates in negative electrode inside is few, can prevent that also the electrolyte in the negative electrode from becoming dry, keep suitable moisture state, and, when heavy-current discharge, also can be discharged to the inner water that generates of catalyst layer outside the electrode efficiently, guarantee the evolving path of gas, thereby no matter what loading condiction from the underload to the high load capacity can obtain the high battery of efficient in whole zone.

In addition, if be that 90% o'clock water vapor adsorption amount is the material with carbon element of 1mL/g～50mL/g, then also can mix material with carbon element more than two kinds as the gaseous diffusion material with carbon element 25 ℃ and relative humidity.

If 25 ℃ and relative humidity is that 90% o'clock water vapor adsorption amount is lower than 1mL/g, then might be difficult to obtain to carry out the effect of humidification from outside batteries, electrolyte is difficult to keep suitable moisture state when starting etc. especially, and proton-conducting descends.

If 25 ℃ and relative humidity is that 90% o'clock water vapor adsorption amount surpasses 50mL/g, then might be when taking out big electric current continuously etc. has little time to discharge, thereby cut off gas diffusion path at the inner water that generates of catalyst layer.

The carbon black that uses in the microporous layers of the present invention can the water vapor adsorption amount be selected from the carbon black of common existence as index.

Perhaps, even have the carbon black of the water vapor adsorption amount that has departed from suitable scope, also can be by handling the suitable scope that is adjusted into.

For example, when the water vapor adsorption amount is too much, might increase the combined amount of fluororesin etc. usually, imparting water repellency makes it satisfy electronic conductivity and gas diffusibility but be difficult to control, so not preferred.Preferably under inert atmosphere, calcine carbon black, make the water vapor adsorption amount be reduced to the method that is fit to scope.For example, can reduce the water vapor adsorption amount by under atmosphere such as argon, nitrogen, helium, vacuum, carrying out heat treated.

In addition, when the water vapor adsorption amount is very few, also can perhaps be exposed under the oxidizing atmosphere environment, make the water vapor adsorption amount increase to suitable scope by material with carbon element is handled carbon material surface with acid or alkali etc.

Though without limits, for example, can or impregnated in the aqueous hydrogen peroxide solution, or in ammonia flow, heat-treat, or impregnated in the sodium hydrate aqueous solution of heating by in the red fuming nitric acid (RFNA) of heating, handling, or at dilution oxygen or dilution NO or NO ₂In carry out heat treated, increase the water vapor adsorption amount.

Second reason of use carbon black is the stereochemical structure of carbon black in microporous layers of the present invention.

A plurality of primary particles of carbon black are melt bonded, form the secondary structure that is called as structure (structure).This structure is according to the difference of kind and prosperity, and the network that becomes primary particle is embraced the structure in space.

In microporous layers, be bonded together by this space, can form the gas diffusion path that is surrounded by the network of primary particle.

Even the gas diffusion path of Xing Chenging is also survivable when connecting battery securely like this, the aperture when being easy to keep microporous layers to form for a long time.In addition, as long as be the kind of index decision carbon black with the structure, then determined the aperture of the gas diffusion path that in microporous layers, forms, so also have the advantage that is easy to control.

In microporous layers of the present invention, as principal component, the preferred carbon black that uses higher structure.This is because if be low structure, then can not expect to form gas diffusion path by structure.Though the degree of structure is observed the method that decides with electron microscope in addition, can judge according to the relation of DBP oil absorption and specific area.

So-called DBP oil absorption, be when instigating dibutyl phthalate to contact with the carbon black of unit mass, the amount of the dibutyl phthalate that is absorbed by carbon black, owing to mainly be absorbed in the gap of primary particle, so as fruit structure is flourishing, then there is the big trend of DBP oil suction quantitative change, not too flourishing as fruit structure, the trend that then exists the DBP oil absorption to diminish.

But, because except the gap of primary particle, DBP also is absorbed in the inner minute aperture that forms of primary particle, so the degree of not necessarily direct representation structure of DBP oil absorption.

This is when becoming big because of the specific area of measuring with the nitrogen adsorbance, and the DBP that is absorbed by minute aperture becomes many, and whole DBP oil absorption also becomes big.

Therefore, in super-normal structure black, come DBP oil suction quantitative change big, on the contrary, in low structure carbon black, come the DBP oil absorption to diminish compared with the nitrogen adsorbance compared with the nitrogen adsorbance.

Preferably, if use DBP oil absorption XmL/100g and nitrogen adsorption specific surface area Ym ²The ratio X/Y of/g is the carbon black more than 1, then can form the microporous layers that possesses desirable gas diffusion path.

This is that structure becomes greatly, can expect to form gas diffusion path by structure because the ratio of X/Y is 1 when above.

The ratio of X/Y is lower than at 1 o'clock, can not expect to form gas diffusion path by structure, gap between the offspring of carbon black mainly forms gas diffusion path, so the hole is easy to damage when connecting in the time can not guaranteeing enough apertures and owing to battery, so bad control is difficult to stably draw the performance of catalyst layer.

More preferably the ratio of X/Y is more than 1.5.If be more than 1.5, then the network of the gas diffusion path that is formed by structure is enough flourishing, even also be difficult for taking place overflow when taking out electric current.

If this structure, then gas is easy to diffusion, and gas diffusion path is difficult for by water slug, thereby is easy to draw the original performance that catalyst layer has.

The carbon black that can be used for micropore of the present invention for example can be by selecting commercially available carbon black to water vapor adsorption amount and DBP oil absorption with ratio research of nitrogen adsorption specific surface area.

Perhaps, when the satisfied scope that is fit to of the ratio of DBP oil absorption and nitrogen adsorption specific surface area, and the water vapor adsorption amount departs from when being fit to scope, can change the water vapor adsorption amount artificially with said method, carries out using after the optimization.

The kind of carbon black so long as usually the carbon black that exists with electronic conductivity get final product, have no particular limits, but preferably can not cause the reaction chemical reaction in addition of original requirement, the material that perhaps constitutes material with carbon element can be because of contacting the material that wash-out goes out with condensing water, and preferred chemically stable material.

In microporous layers, can use aforesaid carbon black as principal component, but also can be compound other material as the accessory ingredient that improves function.

For example, for the surface characteristic of the carbon black that do not damage microporous layers and structure and the mechanical strength that increases also can fix carbon black with macromolecular materials such as a spot of fluororesin.The combined amount of this macromolecular material is below the 40 quality % with respect to the gross mass of microporous layers preferably.

If surpass 40 quality %, the hole that then becomes gas diffusion path can be buried by macromolecular material, and perhaps the hole that is formed by the cohesion of macromolecular material and carbon black can be in the great majority, and is difficult to make the aperture only to rely on structure with carbon black.

More preferably below the 20 quality %.If below 20%, then the influence that is produced by macromolecular material is little, can effectively utilize the formed hole of structure in microporous layers, thereby be easy to control, can form in microporous layers through not labile gas diffusion path for a long time.

The function of gas-diffusion electrode of the present invention is not limited by its manufacture method.

If it is enumerate common manufacture method, then as follows.For example, carbon paper or carbon cloth be impregnated in teflon (テ Off ロ Application) as required, and dispersion liquid (in addition, テ Off ロ Application is a trade mark) in, carry out drying and calcining and carry out the preventing hydration processing, then carbon black and teflon latex are as required mixed and make dispersion liquid, it is applied with sprayer, carry out drying and heat treatment again, form microporous layers, obtain gas diffusion layers of the present invention.

Then, the printing ink that is used to form catalyst layer is applied with sprayer and drying in the microporous layers side, obtain gas-diffusion electrode of the present invention.

When the battery, clip dielectric film with the gas-diffusion electrode of the present invention of two pieces of making, under hot pressing, carry out crimping, the barrier film of packing into formation battery.

In above operation, for example,, can carry out hot pressing in the stage of having finished gas diffusion layers in order to increase the mechanical strength of gas diffusion layers, then, the coating catalyst layer.

In addition, in the coating of microporous layers and catalyst layer,, can utilize powder coating and electrophoresis etc. as long as the method for coating can form microporous layers on the gaseous diffusion fibrage or form catalyst layer on microporous layers.

Perhaps, it is membranaceous to take that also microporous layers and catalyst layer are formed independently of one another, it is the stacked and method of carrying out crimping etc. under hot pressing.

Embodiment

The water vapor adsorption measurement amount of＜material with carbon element 〉

As the material with carbon element that contains in catalyst layer, carbon black A, the B that preparation water vapor adsorption amount is different, C, D, E, F amount to six kinds.B, D and E are commercially available carbon blacks, and A and C carry out heat treated with B and D respectively and obtain in argon.In addition, F after E is handled in the red fuming nitric acid (RFNA) of heating, washes and dry obtaining.

The water vapor adsorption amount of these carbon blacks is used constant volume formula water vapor adsorption device (Japanese ベ Le Co., Ltd. system, BELSORP18) measure, to remain in 25 ℃ the constant temperature at 120 ℃, the sample that carried out degassing pre-treatment in 2 hours below the 1Pa, from between the steam-laden vapour pressure of vacuum state to 25 ℃, supply with steam at leisure and change relative humidity interimly, measure the steam vapour amount of sample absorption.

Describe adsorption isotherm by the measurement result that obtains, from figure, read relative humidity and be 90% o'clock water vapor adsorption amount.It the results are shown in table 1.In addition, the water vapor adsorption amount is that the steam volume that the steam vapour amount of every 1g sample absorption is scaled standard state was represented afterwards.

Table 1

The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm	The designation of Pt catalyst
The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm	The designation of Pt catalyst	A	0.28	32	0.65	0.51	0.01 below	0.12	58	3.9	1
B	3.82	45	0.16	0.58	0.01 below	0.19	85	4.2	2	A	0.28	32	0.65	0.51	0.01 below	0.12	58	3.9	1
B	3.82	45	0.16	0.58	0.01 below	0.19	85	4.2	2	C	35.6	62	0.39	0.62	0.01 below	0.56	96	4.0	3
D	59.8	215	0.35	0.82	0.030	0.85	195	3.6	4	C	35.6	62	0.39	0.62	0.01 below	0.56	96	4.0	3
D	59.8	215	0.35	0.82	0.030	0.85	195	3.6	4	E	82.1	168	0.42	0.61	0.022	1.23	119	3.4	5
F	127	285	0.33	0.64	0.030	1.35	92	3.5	6	E	82.1	168	0.42	0.61	0.022	1.23	119	3.4	5

In addition, in table 1, also show the physics value that the present invention uses simultaneously.Below put down in writing its method of measurement.

They are to be measured by the adsorption isotherm of nitrogen, the elementary analysis value of the area Smicro of the specific area SBET that obtains with the BET method, the micropore (diameter is the pore below the 2nm) obtained with the parsing of t curve and total surface area Stotal, micropore volume Vmicro, oxygen content.

In gas absorption is measured, use the Japanese ベ Le system BELSORP36 of Co., Ltd., the t curve is resolved and is used the analysis program that is attached on the device, calculates above-mentioned physics value.

The DBP oil absorption is following to be determined: use absorption apparatus (Brabender corporate system), 70% o'clock DBP addition of breakdown torque is scaled the DBP oil absorption of every 100g sample.

The particle diameter of Pt particulate (diameter) uses the method for Scherrer by (motor corporate system of science, the half peak breadth at (111) peak of the platinum that RAD-3C) obtains is estimated with the X-ray diffraction device.

(embodiment 1)

In chloroplatinic acid aqueous solution, disperse carbon black A, B, C, D, E, F respectively as the catalyst carrier material with carbon element, under 50 ℃, be incubated, add aquae hydrogenii dioxidi while stir, then add Na ₂S ₂O ₄The aqueous solution obtains catalyst precarsor.

With this catalyst precarsor filtration, washing, drying, then at 100%H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the Pt catalyst 1～6 of 30 quality %Pt that has been modulated on the catalyst carrier material with carbon element load.In table 1, show the Pt particle diameter of Pt catalyst 1～6 simultaneously.The Pt particle diameter of catalyst is 3～4nm.

In container, put into the Pt catalyst 1～6 of modulation, to wherein adding 5%Nafion solution (ア Le De リッチ system) so that the mass ratio of Pt catalyst and Nafion is 1/1.4, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring, so that the solid component concentration that Pt catalyst and Nafion lump together is 6 quality %, thereby modulation catalyst printing ink 1～6.

Then, in another container, put into black B, add butyl acetate, use the ultrasonic-wave crushing carbon black so that the concentration of carbon black is 6 quality % as the gaseous diffusion material with carbon element, thus modulation gas diffused carbon material printing ink 1.

Then, the catalyst ink 1～6 of modulation is respectively got 10g and put into each container, stir after adding 2.5g gaseous diffusion material with carbon element printing ink 1 respectively, thus modulation catalyst layer printing ink 1～6.

Be coated on thin teflon (the テ Off ロ Application) thin slice respectively these catalyst layer printing ink 1～6 and drying, on teflon sheets, form catalyst layer, be cut into the square of 2.5cm * 2.5cm, make catalyst for cathode layer-teflon sheets conjugant 1～6 respectively.

In addition, repeat to be coated on the thin teflon sheets catalyst ink 4 and dry operation, on teflon sheets, form catalyst layer, be cut into the square of 2.5cm * 2.5cm, make anode catalyst layer-teflon sheets conjugant A.

With the catalyst for cathode layer-teflon sheets conjugant 1～6 of these making and anode with catalyst layer-teflon sheets conjugant A respectively each 1 piece clip dielectric film (Nafion112) after making up, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing after 3 minutes, only peel off teflon sheets, make catalyst layer-dielectric film conjugant 1～6.

At this moment, according to the quality that is transferred to the catalyst layer on the dielectric film that decides of poor quality of the catalyst layer-quality of teflon sheets conjugant and the teflon sheets of peeling off, and obtain Pt content according to the composition of itself and printing ink.

At this moment, adjust in advance catalyst layer printing ink is coated in the amount on the teflon sheets so that the Pt content of negative electrode is 0.07mg/cm ², anode Pt content be 0.04mg/cm ²

In addition, the carbon paper that has carried out water-proofing treatment with PTFE in advance is cut into the square of 2.5cm * 2.5cm, uses 2 pieces and clip catalyst layer-dielectric film conjugant, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing 3 minutes again, obtain carbon paper-catalyst layer-dielectric film conjugant 1～6 (MEA1～MEA6).

Below, carbon paper-catalyst layer-dielectric film conjugant brief note is MEA.

Packed in the fuel cell measurement mechanism in MEA1～6 that obtain, carry out battery performance and measure.The battery performance measurement is to make between battery terminal voltage (be generally about 0.9V～1.0V) change to 0.2V interimly, measure the current density that flows through when voltage is for 0.6V between battery terminal from open circuit voltage.

Gas is to supply with pure hydrogen so that utilance is respectively 50% and 80% to negative electrode air supply, anode, uses the counterbalance valve that is arranged on the battery downstream to carry out the pressure adjustment to gas separately, and is set at 0.1MPa.Battery temperature is set at 80 ℃, and the air of supply and pure hydrogen are to carry out bubbling in the distilled water of 80 ℃ and 90 ℃ in insulation respectively, thus humidification.

Table 2

In the table 2, show the battery performance measurement result of MEA1～6 with the composition of catalyst layer.As shown in table 1, the catalyst carrier material with carbon element is that 90% o'clock water vapor adsorption amount is that more excellent battery performance has been brought into play than MEA1～3 of comparative example in MEA4～6 of the embodiment of the invention more than the 50mL/g 25 ℃ and relative humidity.

(embodiment 2)

In chloroplatinic acid aqueous solution, disperse carbon black D as the catalyst carrier material with carbon element, under 50 ℃, be incubated, add aquae hydrogenii dioxidi while stir, then add Na ₂S ₂O ₄The aqueous solution obtains catalyst precarsor.

With this catalyst precarsor filtration, washing, drying, then at 100%H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the Pt catalyst 7 of 20 quality %Pt that has been modulated on the catalyst carrier material with carbon element load.The Pt particle diameter of Pt catalyst 7 is 3～4nm.

In container, put into the Pt catalyst 7 of modulation, to wherein adding 5%Nafion solution (ア Le De リッチ system) so that the mass ratio of Pt catalyst 1 and Nafion is 1/1.6, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring, so that the solid component concentration that Pt catalyst 1 and Nafion lump together is 6 quality %, thereby modulation catalyst printing ink 7.

Then, in another container, put into carbon black C, add butyl acetate,, use the ultrasonic-wave crushing carbon black so that the concentration of carbon black is 6 quality % as the gaseous diffusion material with carbon element, thus modulation gas diffused carbon material printing ink 2.

Then, catalyst ink 7 each 10g of modulation are put into 7 containers, add 0g, 0.204g, 0.870g, 1.111g, 2.500g, 4.286g, 12.222g gaseous diffusion material with carbon element printing ink 2 respectively and stir, thus modulation catalyst layer printing ink 7～13.

Repeat to be coated on the thin teflon sheets respectively these catalyst layer printing ink 7～13 and dry operation, on teflon sheets, form catalyst layer, be cut into the square of 2.5cm * 2.5cm, make catalyst for cathode layer one teflon sheets conjugant 7～13 respectively.

The anode made from the catalyst for cathode layer-teflon sheets conjugant 7～13 of these making with by embodiment 1 with catalyst layer-teflon sheets conjugant A respectively respectively 1 piece clip dielectric film (Nafion112) after making up, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing after 3 minutes, only peel off teflon sheets, make catalyst layer-dielectric film conjugant 7～13.At this moment, according to the quality that is transferred to the catalyst layer on the dielectric film that decides of poor quality of the catalyst layer-quality of teflon sheets conjugant and the teflon sheets of peeling off, and obtain Pt content according to the composition of itself and printing ink.At this moment, adjust in advance catalyst layer printing ink is coated in the amount on the teflon sheets so that the Pt content of negative electrode is 0.07mg/cm ², anode Pt content be 0.04mg/cm ²

In addition, the carbon paper that has carried out water-proofing treatment with PTFE in advance is cut into the square of 2.5cm * 2.5cm, uses 2 pieces and clip catalyst layer-dielectric film conjugant, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing 3 minutes again, obtain MEA7～13.

Battery performance is carried out in MEA7～13 that obtain under the condition identical with embodiment 1 measure.

Table 3

In the table 3, show the battery performance measurement result of MEA7～13 with the composition of catalyst layer.As shown in table 3, more excellent battery performance has been brought into play than the comparative example MEA7 that does not contain the gaseous diffusion material with carbon element in MEA8～13 that negative electrode contains the embodiment of the invention of gaseous diffusion material with carbon element.

In addition, in MEA7～13 as embodiment, excellent especially performance has been brought into play in MEA9～12 of containing 5 quality %～50 quality % gaseous diffusion material with carbon elements.

(embodiment 3)

In chloroplatinic acid aqueous solution, disperse carbon black F, under 50 ℃, be incubated, add aquae hydrogenii dioxidi, then add Na while stir as the catalyst carrier material with carbon element ₂S ₂O ₄The aqueous solution obtains catalyst precarsor.With this catalyst precarsor filtration, washing, drying, then at 100%H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the Pt catalyst 8 of 50 quality %Pt that has been modulated on the catalyst carrier material with carbon element load.The Pt particle diameter of Pt catalyst 8 is 3～4nm.

In container, put into the Pt catalyst 8 of modulation, to wherein adding 5%Nafion solution (ア Le De リッ is in system) so that the mass ratio of Pt catalyst and Nafion is 1/2, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring, so that the solid component concentration that Pt catalyst and Nafion lump together is 6 quality %, thereby modulation catalyst printing ink 8.

Then, in another container, put into carbon black A, B, C, D, E, F respectively, add butyl acetate, use the ultrasonic-wave crushing carbon black so that the concentration of carbon black is 6 quality % as the gaseous diffusion material with carbon element, thus modulation gas diffused carbon material printing ink 3～8.

Then, catalyst ink 8 each 10g of modulation are put into 6 containers, add 3.333g gaseous diffusion material with carbon element printing ink 3～8 respectively and stir, thus modulation catalyst layer printing ink 14～19.

Be coated on the thin teflon sheets respectively these catalyst layer printing ink 14～19 and drying, on teflon sheets, form catalyst layer, be cut into the square of 2.5cm * 2.5cm, make catalyst for cathode layer-teflon sheets conjugant 14～19 respectively.

The anode made from the catalyst for cathode layer-teflon sheets conjugant 14～19 of these making with by embodiment 1 with catalyst layer-teflon sheets conjugant A respectively respectively 1 piece clip dielectric film (Nafionl12) after making up, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing after 3 minutes, only peel off teflon sheets, make catalyst layer one dielectric film conjugant 14～19, adjust similarly to Example 1 so that the Pt content of negative electrode is 0.07mg/cm ², anode Pt content be 0.04mg/cm ²

In addition, the carbon paper that similarly to Example 1 will be have in advance carried out water-proofing treatment with PTFE engages, and obtains MEA14～19.

Battery performance is carried out in MEA14～19 that obtain under the condition identical with embodiment 1 measure.

Table 4

In the table 4, show the battery performance measurement result of MEA14～19 with the composition of catalyst layer.As shown in table 4, more excellent battery performance has been brought into play than the comparative example MEA7 that does not contain the gaseous diffusion material with carbon element in embodiment of the invention MEA14～19 of containing the gaseous diffusion material with carbon element in the negative electrode.

In addition, in MEA14～19, the gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is that excellent especially battery performance has been brought into play in MEA14～18 below the 100mL/g 25 ℃ and relative humidity, in addition, the gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is that the MEA15 and 16 of 1mL/g～50mL/g has brought into play extremely excellent battery performance 25 ℃ and relative humidity

(embodiment 4)

As raw material, in insulation was 800 ℃～1100 ℃ heating furnace, the limit made the nitrogen current that contains a certain amount of steam cross the limit and handled 2～3 hours, carried out so-called steam activation and handled, thereby make active carbon coal class green coke charcoal.

In addition, in order to control oxygen content, under the nitrogen atmosphere that contains 10 volume %～30 volume % hydrogen, under 500 ℃～900 ℃, carry out heat of reduction and handled 1 hour.

In table 5, conclude the various rerum naturas that show a series of active carbons of making of said method.These physics values are measured with above-mentioned method.

Table 5

The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm
The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm	Active carbon 1	195.3	1550	0.55	0.73	0.311	4.93	35	1.9
Active carbon 2	183.3	1640	0.52	0.85	0.362	4.33	45	1.7	Active carbon 1	195.3	1550	0.55	0.73	0.311	4.93	35	1.9
Active carbon 2	183.3	1640	0.52	0.85	0.362	4.33	45	1.7	Active carbon 3	165.1	1890	0.68	1.18	0.758	4.62	75	1.7
Active carbon 4	205.3	2310	0.85	1.32	1.300	3.55	70	1.6	Active carbon 3	165.1	1890	0.68	1.18	0.758	4.62	75	1.7
Active carbon 4	205.3	2310	0.85	1.32	1.300	3.55	70	1.6	Active carbon 5	166.6	1750	0.95	1.05	0.873	3.81	60	1.8
Active carbon 6	45.6	1320	0.41	0.75	0.203	4.51	35	3.8	Active carbon 5	166.6	1750	0.95	1.05	0.873	3.81	60	1.8
Active carbon 6	45.6	1320	0.41	0.75	0.203	4.51	35	3.8	Active carbon 7	31.9	1650	0.31	0.55	0.141	10.5	25	4.5
G	46.6	225	0.12	0.55	0.01 below	1.56	220	5.3	Active carbon 7	31.9	1650	0.31	0.55	0.141	10.5	25	4.5
G	46.6	225	0.12	0.55	0.01 below	1.56	220	5.3	H	29.6	80	0.09	0.45	0.01 below	0.96	170	6.7

For load platinum particulate on these active carbons, carry out following operation.In the flask that has added 150mL distilled water, add the material with carbon element 0.5g be used for carrier and (IV) acid of chlordene platinum so that platinum is 1:1 with respect to the mass ratio of carrier, after fully disperseing with ultrasonic wave, in oil bath, keep fluidized state, to wherein dripping as the formaldehyde of reducing agent 3～10 hours with certain speed.

Drip the end back and carry out isolated by filtration with film filter, regenerant is disperseed in distilled water once more, the operation of triplicate isolated by filtration 100 ℃ of following vacuumizes, forms the catalyst that electrode is used.

The platinum amount that loads on the catalyst is carried out quantitatively with the luminescence of plasma analytic approach after being dissolved in hot chloroazotic acid, and which sample all is 50 quality % as a result.The particle diameter of the platinum catalyst that obtains has been shown in the table 5.

The active carbon of the present invention regulation and other active carbon or carbon black relatively, although load the such high density of 50 quality %, also can obtain the particle diameter below the 2.0nm, thereby obviously find out the Pt particle diameter is diminished, be excellent as carrier.

Use this a series of platinum supported catalyst material with carbon element and as the black B of the embodiment 1 of gaseous diffusion material with carbon element, use the method identical, make catalyst for cathode layer-teflon sheets conjugant with embodiment 1.

The anode made from the catalyst for cathode layer-teflon sheets conjugant of these making with by embodiment 1 with catalyst layer-teflon sheets conjugant A respectively respectively 1 piece clip dielectric film (Nafion112) after making up, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing after 3 minutes, only peel off teflon sheets, make catalyst layer-dielectric film conjugant, adjust so that the Pt content of negative electrode is 0.08mg/cm ², anode Pt content be 0.05mg/cm ²

In addition, the carbon paper that similarly to Example 1 will be have in advance carried out water-proofing treatment with PTFE engages, and obtains MEA.The MEA that obtains is carried out battery performance under the condition identical with embodiment 1 measure.

Table 6

In the table 6, show the battery performance result of the MEA of making.Use active carbon to compare, can confirm obviously to have brought into play excellent output characteristic as the MEA of the platinum catalyst of carrier and the MEA of active carbon that uses as a comparison and carbon black with the present invention's regulation.

(embodiment 5)

In order to improve life of catalyst research, in the material with carbon element that embodiment 4 uses, 5 kinds shown in the table 7 as carrier, are used the method load platinum particulate identical with embodiment 4 to being used for carrier by active carbon with the present invention regulation.

In this research,, must make the particle diameter of the platinum particulate before the deterioration consistent exactly, make catalyst so that the platinum load factor is the diameter of 30 quality % and platinum particulate is 2.3nm for the change of size of catalyst is estimated as deterioration.In the table 7, show the physics value and the catalyst particle size of a series of material with carbon elements.Catalyst particle size uses the value of measuring with X-ray diffraction method.

Use 5 kinds of catalyst of table 7, use the method identical to make MEA with embodiment 4.MEA is so that the Pt content of negative electrode is 0.08mg/cm in modulation ², anode Pt content be 0.05mg/cm ²Use the method identical to pack in the battery MEA that obtains, in evaluation with embodiment 1.

The life of catalyst evaluation be with before the deterioration of the surface area of the platinum that uses at negative electrode with the deterioration running after ratio estimate.That is,, then the deterioration rate is evaluated as 0% when deterioration turns round,, then the deterioration rate is evaluated as 50% if deterioration running back platinum surface area is before the deterioration half if the surface area of platinum does not change fully.

The surface area of the platinum of negative electrode is in order to method evaluation down.Anode is supplied with the hydrogen of humidification, to the argon gas of negative electrode supply humidification, cell voltage is circulated 10 times in the scope of 0.05V～0.9V, measures cyclic voltammogram (cyclic voltamogram).

Humidified condition, battery temperature are set at the condition identical with embodiment 1.Converse the number of hydrogen atoms of disengaging by the area of the so-called hydrogen disengaging ripple on the curve of the 10th circulation, 1 atomic hydrogen is accounted for the average area on platinum surface as known, obtain the surface area of platinum (with reference to the rattan Shima by number of hydrogen atoms, damp mutually, aboveground work, the electrochemical mensuration (on), skill newspaper hall is published (strain), the pre-treatment and the electrode surface area of 4.4 electrodes of the 4th chapter).

In this evaluation, after each MEA grouping, at first measure cyclic voltammogram, then, the gas of negative electrode is become pure oxygen, cell voltage after 0CV (uncharge open circuit voltage) down keeps 15 seconds, is kept 15 seconds so that cell voltage is constant in 0.5V applying under the state of load, repeat this operation 3000 times.

Then, again the gas of negative electrode is become argon, with deterioration before obtain the surface area of platinum under the identical condition.The deterioration rate is to represent the value of the platinum surface area after the deterioration before with deterioration removed the value of gained with percentage.

Table 7

	Material with carbon element	Pt particle diameter nm	Deterioration rate %
	Material with carbon element	Pt particle diameter nm	Deterioration rate %	Embodiment	Active carbon 1 active carbon 2 active carbons 4	2.26 2.29 2.26	41 40 37
Comparative example	Active carbon 6 active carbons 7 G H	2.28 2.30 2.29 2.32	55 59 63 69	Embodiment	Active carbon 1 active carbon 2 active carbons 4	2.26 2.29 2.26	41 40 37

Find out obviously that by table 7 degradation of the active carbon of the present invention regulation is obviously than little with other active carbon or the common carbon black platinum catalyst that is used for carrier.

(embodiment 6)

In the present embodiment,, comprise that comparative example uses pore volume, nitrogen adsorption specific surface area, DBP oil absorption, material with carbon element that the water vapor adsorption amount is different as catalyst carrier.The various physics values of the material with carbon element that uses have been shown in the table 8.

Table 8

The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm
The kind of material with carbon element	Water vapor adsorption amount mL/g	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Micropore volume mL/g	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm	I	25.3	72	0.41	0.68	0.01	1.12	170	6.3
J	78.5	1370	0.39	0.63	0.17	0.78	521	2.0	I	25.3	72	0.41	0.68	0.01	1.12	170	6.3
J	78.5	1370	0.39	0.63	0.17	0.78	521	2.0	K	82.9	796	0.73	0.69	0.2	1.23	360	2.5
L	113.5	1436	0.77	0.71	0.39	0.96	313	2.0	K	82.9	796	0.73	0.69	0.2	1.23	360	2.5
L	113.5	1436	0.77	0.71	0.39	0.96	313	2.0	M	103.5	950	0.35	0.66	0.11	0.86	380	2.4
N	48.3	227	0.48	0.92	0.05	2.1	219	3.5	M	103.5	950	0.35	0.66	0.11	0.86	380	2.4
N	48.3	227	0.48	0.92	0.05	2.1	219	3.5	O	46.1	195	0.25	0.81	0.02	0.98	127	4.5
P	41.6	460	0.40	0.77	0.07	1.63	150	3.0	O	46.1	195	0.25	0.81	0.02	0.98	127	4.5
P	41.6	460	0.40	0.77	0.07	1.63	150	3.0	Q	43.9	265	0.37	0.82	0.04	1.22	119	3.5
R	39.8	583	0.11	0.99	0.03	1.41	95	2.8	Q	43.9	265	0.37	0.82	0.04	1.22	119	3.5
R	39.8	583	0.11	0.99	0.03	1.41	95	2.8	S	37.7	40	0.52	0.97	0.01	0.82	159	7.2
T	68.8	1582	0.69	0.71	0.39	1.26	515	1.8	S	37.7	40	0.52	0.97	0.01	0.82	159	7.2

Above-mentioned physics value is measured with above-mentioned method.The material with carbon element of table 8 as catalyst carrier, is made the platinum supported catalyst with following method.

In water, disperse material with carbon element respectively as the table 8 of catalyst carrier material with carbon element, under 50 ℃, be incubated, add chloroplatinic acid aqueous solution and formalin while stir, obtain catalyst precarsor.

After this catalyst precarsor filtration, washing, drying, at 100%H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the platinum catalyst of 20 quality % platinum that has been produced on the catalyst carrier material with carbon element load.

The Pt particle diameter of the platinum catalyst that obtains has been shown in the table 8.As shown in table 8, the crystallite diameter of material with carbon element I, O, S becomes very big, envisions the battery catalyst that acts as a fuel, and performance can be too not high.

Use above-mentioned 12 kinds of catalyst carrier material with carbon elements and as the black B of the embodiment 1 of gaseous diffusion material with carbon element, use the method identical, make catalyst for cathode layer-teflon sheets conjugant with embodiment 1.

In addition, the carbon paper that similarly to Example 1 will be have in advance carried out water-proofing treatment with PTFE engages, and obtains MEA29～MEA40.

MEA29～MEA40 of obtaining is carried out battery performance under the condition identical with embodiment 1 measure.

Table 9

In the table 9, show the battery performance result of 12 kinds of MEA of making.MEA30 of the present invention～33,40 are compared with other comparative example and have been shown excellent battery performance.

Wherein, use the following pore volume of 2nm as more than the 0.3mL/g and also the nitrogen adsorption specific surface area be 800m ²Above and the DBP oil absorption of/g is that the part throttle characteristics of MEA40 of the above material with carbon element T of 400mL/g is outstanding especially.

(embodiment 7)

The synthetic method of＜transition metal complex 〉

Below show the synthetic method of the N4 chelate type transition metal complex of stipulating among the present invention.

Synthesizing of complex compound 1: with document (R.H.Holm, J.Am.Chem.Soc., Vol.94, p.4529 (1972)) the middle method of putting down in writing, synthetic 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclododecane ten four-2,4,6, the cobalt of 9,11,13-six alkene (II) complex compound (abbreviating complex compound 1 as).Yield 12%.

Synthesizing of complex compound 2: with document ((a) T.Hayashi, Bull.Chem.Soc.Jpn., Vol.54, p.2348 (1981), (b) R.H.Holm, Inorg.Syn., Vol.11, p.72 (1968)) the middle method of putting down in writing, synthetic 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclododecane ten four-4,6,11, the cobalt of 13-tetraene (II) complex compound (abbreviating complex compound 2 as).Yield 8%.

＜catalyst modulation 〉

As the material with carbon element carrier that catalyst is used, use material with carbon element F that in embodiment 1, uses and the active carbon 3 that in embodiment 4, uses and active carbon 4 to amount to three kinds.Quality % according to the rules measures chloroplatinic acid hexahydrate (with the pure medicine of light Co., Ltd. system), and in being diluted with water to the aqueous solution of appropriate amount, adding is used as the material with carbon element of carrier and fully stirs, and disperses with supersonic generator then.

Then, use evaporator, make the dispersion liquid dry solidification, the carrier of precursor of having made load.

With this load the carrier of precursor flowing through electric furnace that the hydrogen/argon mixture gas is arranged (ratio of hydrogen: be heated to 300 ℃ 10～50 volume %), carry out the reduction of chloroplatinic acid and handle.The particle diameter of Pt is 2.0～2.3nm.

Count 1 quality % according to converting and measure above-mentioned transition metal complex with transition metal, to the N that has added appropriate amount, in the solution of N '-dimethyl formamide (the superfine grade of reagent) or pyridine (the superfine grade of reagent), the material with carbon element of platinum (Pt-C) that added above-mentioned load also fully stirs, and disperses with supersonic generator again.

The limit is incubated dispersion liquid in 70 ℃ oil bath, (refluxing) refluxed more than 8 hours in the limit in argon, is injected into while stirring then in the above distilled water of 5 times of amounts of dispersion liquid, carries out transition metal complex fixing on Pt-C.

Then, separate the collection catalyst by filtration under diminished pressure, the distilled water with about 60 ℃ of temperature washs once more, gathers catalyst by filtration under diminished pressure, carries out vacuumize under 100 ℃.

In addition, in argon gas atmosphere, handled 1 hour down, form the catalyst of estimating usefulness at 700 ℃.

The transition metal complex that uses among the embodiment is above-mentioned complex compound 1 and complex compound 2 and 5,10, the cobalt of 15,20-tetraphenylporphyrin (II) complex compound (being abbreviated as CoTPP).

In addition, in load only in the modulation of catalyst of transition metal complex, remove the operation of above-mentioned load platinum, and only carry out the load operation of transition metal complex, in addition, in load only in the modulation of catalyst of platinum, the load operation of removing transition metal complex, and only carry out the operation of load platinum, modulate each catalyst.

The evaluation method of＜catalyst activity 〉

(1) estimates the modulation of using sample

With catalyst fines 15mg and the polymer solid electrolyte solution (EC-NS-05 of U.S. ElectroChem company that obtains with the mortar crushing catalyst in advance; Nafion 5 quality % solution) during 300mg and ethanol 300mg pack sample bottle into, use stirrer to stir 15 minutes with blender, thus the abundant mixing slurry of modulation.

(2) modulation of the test utmost point

On the disk electrode of rotating ring disk electrode, apply above-mentioned slurry and dry, form the test utmost point.Disk electrode is that the diameter made from vitreous carbon (glassy carbon) is the cylinder of 6mm, sample application on its bottom surface.Coating amount is adjusted into 0.03mg.

In addition, ring electrode is that internal diameter is that 7.3mm, external diameter are the cylinder of the platinum system of 9.3mm, in the rotating ring disk electrode, disk electrode and ring electrode are positioned at concentric position, form the structure of between disk electrode and the ring electrode and the outside of ring electrode having been carried out insulation with teflon resin.

(3) evaluation method

Use the rotating ring disk evaluating apparatus (RRDE-1) of (having) day thick instrumentation, catalyst is carried out electrochemical activity rating.In electrochemical evaluation, use the SI1287 of 2 ソ-ラ-トロ Application company, independent control ring electrode and disk electrode carry out bipolar measurement.

As electrolyte, use the aqueous sulfuric acid of 0.1N, and form the battery structure that the benchmark utmost point uses SCE electrode, polarity use Pt plate.Appreciation condition is as follows.

Make bubble oxygen, under oxygen-saturated electrolyte state, to scanning-0.2V from 1.0V (SCE standard) with the current potential of the disk electrode of the electrode of 2500rpm rotation speed with 10mV/sec, at this moment, the current potential of retaining ring electrode is 1.1V (a SCE standard), the timeliness of the electric current that measurement is flow through in disk electrode, ring electrode changes, thereby obtains disk electric current, the circular current curve with respect to the current potential of disk electrode.

(4) overvoltage evaluation assessment

From the curve of above-mentioned disk current potential to the disk electric current, the current potential (E1/2) when reading in half current value of saturation current value.Current potential E1/20 during half current value of the saturation current value of the EC10PTC of U.S. ElectroChem corporate system catalyst (on carbon black load the catalyst of 10 quality % platinum) estimates the Δ E1/2=E1/2-E1/20 of embodiment, each catalyst of comparative example as standard.

That is, then have identical overvoltage during Δ E1/2=0, if Δ E1/2 with EC10PTC〉0, then overvoltage is also littler than EC10PTC, corresponding to the catalytic activity height.

The evaluation assessment of (5) 4 electron reaction rates

With respect to the curve of disk current potential, calculate 4 electron reaction rate η from circular current and disk electric current according to following formula.

η(％)＝[Id-(Ir/n)]/[Id+(Ir/n)]

Wherein, Id represents the disk electric current, and Ir representative ring electric current, n are represented the catch rate by the disk product of ring electrode generation.

The experimental measurement method of catch rate is estimated according to " the rattan Shima is clear etc., electrochemical determination method (descend), skill newspaper hall is published (1991) ", the result in the electrode of embodiment use, n=0.36.

In addition, η changes (current potential is low more, and it is more little that η becomes) according to the disk current potential, but for the difference that makes the η that is produced by catalyst becomes clearly, the η when adopting the disk current potential to be 0V (SCE standard) in this evaluation.

In the table 11, conclude and to show transition metal kind, platinum load capacity, as the overvoltage value Δ E1/2 and the 4 electron reaction rate η of catalytic activity index.

Table 11

By the result of table 11 as can be seen, catalytic activity, the 4 electron reaction rates of transition metal complex in oxygen reduction reaction of the ad hoc structure of the present invention's regulation are all good.

In addition, the composite catalyst that the transition metal complex and the platinum of the present invention regulation is combined to form than independent platinum, transition metal complex shows the catalysis characteristics of obvious excellence separately, has confirmed the synergy of transition metal complex and platinum.

In addition, also can confirm the effect of carrier, be applicable to carrier, can show that common carbon carrier can not be brought into play, excellent catalytic activity by the active carbon that specific area is big.

Then, use catalyst 3, catalyst 4, catalyst 5, catalyst 6,8 five kinds of catalyst of catalyst and, use the method identical, make catalyst for cathode layer-teflon sheets conjugant with embodiment 1 as the black B of the embodiment 1 of gaseous diffusion material with carbon element.

The anode made from the catalyst for cathode layer-teflon sheets conjugant of these making with by embodiment 1 with catalyst layer-teflon sheets conjugant A respectively respectively 1 piece clip dielectric film (Nafion112) after making up, at 140 ℃, 100kg/cm ²Condition under carry out hot pressing after 3 minutes, only peel off teflon sheets, make catalyst layer-dielectric film conjugant, adjust so that the Pt content of anode is 0.03mg/cm ²

The Pt content of negative electrode is according to 0.03mg/cm for catalyst 3, catalyst 4, catalyst 5, catalyst 6 ²Modulating, is according to 0.06mg/cm for catalyst 8 ²Modulate.

In addition, the carbon paper that similarly to Example 1 will be have in advance carried out water-proofing treatment with PTFE engages, and obtains MEA41～MEA45.

MEA41～MEA45 of obtaining is carried out battery performance under the condition identical with embodiment 1 measure.

Table 12

In the table 12, show the battery performance result of 5 kinds of MEA of making.MEA41-44 compares with MEA45, although the platinum amount of negative electrode is half, also can show excellent battery performance.

(embodiment 8)

When representing the embodiment of gas-diffusion electrode of the present invention, prepare three kinds of carbon black U, V, W.In the table 13, show water vapor adsorption amount, DBP oil absorption (XmL/100g), the nitrogen adsorption specific surface area (Ym of various carbon blacks ²/ g) and the ratio X/Y of DBP oil absorption and nitrogen adsorption specific surface area.

Table 13

The kind of carbon black	Water vapor adsorption amount mL/g	DBP oil absorption (X) mL/100g	Nitrogen adsorption specific surface area (Y) m ²/g	X/Y
The kind of carbon black	Water vapor adsorption amount mL/g	DBP oil absorption (X) mL/100g	Nitrogen adsorption specific surface area (Y) m ²/g	X/Y	U	8.96	232	128	1.81
V	59.8	230	225	1.02	U	8.96	232	128	1.81
V	59.8	230	225	1.02	W	127	536	1370	0.39

The making of＜gas diffusion layers 〉

Prepare commercially available carbon cloth (EC-CC1-060 of ElectroChem society system), they be impregnated in be diluted in 5% the teflon dispersion liquid, dry then, in argon gas stream, be warming up to 340 ℃ and make the gaseous diffusion fibrage again.In addition, in 1g carbon black U, add ethanol 99g, pulverize carbon black, make dispersion liquid one time with ball mill.

Then, a dispersion liquid is stirred on the limit, and the limit drips 30% teflon dispersion liquid 0.833g bit by bit, makes the microporous layers slurry.

Use sprayer to be coated on the gaseous diffusion fibrage of above-mentioned making in this slurry, in argon gas stream, after 80 ℃ of following dryings, be warming up to 340 ℃, make the gas diffusion layers CC-U that gaseous diffusion fibrage and microporous layers are laminated.

As a comparison, also prepared the gas diffusion layers CC of the carbon cloth that does not apply microporous layers.

In chloroplatinic acid aqueous solution, disperse carbon black V, W respectively as the table 13 of catalyst carrier material with carbon element, under 50 ℃, be incubated, add aquae hydrogenii dioxidi while stir, then add Na ₂S ₂O ₄The aqueous solution obtains catalyst precarsor.With this catalyst precarsor filtration, washing, drying, then at 100H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the two kinds of Pt catalyst of 20 quality %Pt that have been modulated on the catalyst carrier material with carbon element load.

In container, put into this two kinds of Pt catalyst, in argon gas stream, add 5%Nafion solution (ア Le De リッチ system) so that the quality of Nafion solid constituent is 2 times with respect to the quality of Pt catalyst, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring, so that the solid component concentration that Pt catalyst and Nafion lump together is 6 quality %, thereby modulate two kinds of catalyst pulps.

In another container, put into the carbon black U shown in the table 13, add butyl acetate,, use the ultrasonic-wave crushing carbon black, thereby make the carbon black slurry so that carbon black is 6 quality %.

The two kinds of catalyst pulps respectively and the carbon black slurry of above-mentioned making are mixed with mass ratio 8:2, fully stir, make two kinds of catalyst pulps.

These two kinds of catalyst pulps are coated in respectively on the gas diffusion layers CC-U with sprayer, in 80 ℃ argon gas stream dry 1 hour, thus obtain in catalyst layer, to contain as carbon black V, the W of catalyst carrier material with carbon element and as two kinds of gas-diffusion electrodes of the present invention of the carbon black U of gaseous diffusion material with carbon element.

In addition as a comparison, do not applying on the carbon cloth CC of microporous layers, also obtaining in catalyst layer, to contain as the carbon black W of catalyst carrier material with carbon element and as the gas-diffusion electrode of the carbon black U of gaseous diffusion material with carbon element, as a comparative example.

In addition, be 0.10mg/cm according to the platinum use amount in each electrode ²Set conditions such as injection.The platinum use amount is obtained by its poor calculating by measuring the dry mass of spraying front and back electrode.

In addition, respectively intercept two pieces according to the square size of 2.5cm, clip dielectric film (Nafion112), under 130 ℃, stagnation pressure 0.625t, carried out hot pressing 3 minutes, make MEA46～48 3 kind with two pieces of electrodes of identical type by the gas-diffusion electrode that obtains.

Three kinds of MEA that obtain are respectively charged in the fuel cell measurement mechanism, carry out battery performance and measure.The battery performance measurement is to make between battery terminal voltage (be generally about 0.9V～1.0V) change to 0.2V interimly, measure the current density that flows through when voltage is 0.8V and 0.5V between battery terminal respectively from open circuit voltage.

Gas is to supply with pure hydrogen so that utilance is respectively 50% and 80% to negative electrode air supply, anode, uses the counterbalance valve that is arranged on the battery downstream that pressure is adjusted into 0.1MPa to air pressure separately.Battery temperature is set at 80 ℃, and the air of supply and pure hydrogen are to carry out bubbling in the distilled water of 80 ℃ and 90 ℃ in insulation respectively, thus humidification.

The three kinds of MEA and the battery performance result that obtain have been shown in the table 14.As shown in table 14, MEA of the present invention has brought into play excellent characteristic.

Especially in gas diffusion layers, have with 25 ℃ and relative humidity be 90% water vapor adsorption amount be carbon black below the 100mL/g as the MEA46 and 47 of the microporous layers of principal component, compare with the MEA48 that does not have microporous layers and to have shown excellent characteristic.

Wherein, containing 25 ℃ and relative humidity in catalyst layer is that 90% water vapor adsorption amount is that the MEA47 of the catalyst carrier material with carbon element more than the 100mL/g has brought into play extremely excellent performance.

Table 14

(embodiment 9)

Preparation carbon cloth (EC-CC1-060 of ElectroChem corporate system) impregnated in them and is diluted in 5% the teflon dispersion liquid, and is dry then, is warming up to 320～350 ℃ and make the gaseous diffusion fibrage again in argon gas stream.

In addition, in two kinds of carbon black 1g of table 15, add ethanol 99g respectively, pulverize the raw material of wood-charcoal material, make dispersion liquid one time with ball mill.

Then, the limit is stirred a dispersion liquid limit and is dripped 30% teflon dispersion liquid 0.833g bit by bit, makes the microporous layers slurry.

Use sprayer to be coated on the fibrolaminar face of gaseous diffusion of above-mentioned making in this slurry, in argon gas stream, after 80 ℃ of following dryings, be warming up to 320～350 ℃, make two kinds of gas diffusion layers that gaseous diffusion fibrage and microporous layers are laminated.

In the table 15, conclude the various rerum naturas that show the carbon black that uses in the microporous layers.

Table 15

The carbon black that uses in the microporous layers	Nitrogen adsorption specific surface area (Y) m ²/g	DBP oil absorption (X) mL/100g	X/Y	Water vapor adsorption amount mL/g
The carbon black that uses in the microporous layers	Nitrogen adsorption specific surface area (Y) m ²/g	DBP oil absorption (X) mL/100g	X/Y	Water vapor adsorption amount mL/g	AA	78	160	2.05	4.5
AB	219	221	1.01	62	AA	78	160	2.05	4.5

As catalyst, use having the platinum catalyst of the active carbon of rerum natura shown in the table 16 as carrier.For load platinum particulate on this active carbon, carry out following operation.

In the flask that has added 150mL distilled water, add as the active carbon 0.5g of catalyst carrier and (IV) acid of chlordene platinum so that platinum is 1:1 with respect to the mass ratio of carrier, after fully disperseing with ultrasonic wave, in oil bath, keep fluidized state, to wherein dripping formaldehyde as reducing agent with certain speed.

Drip the end back and carry out isolated by filtration with film filter, regenerant is disperseed in distilled water once more, the operation of triplicate isolated by filtration 100 ℃ of following vacuumizes, forms the catalyst that electrode is used.The platinum amount that loads on the catalyst is carried out quantitatively with the luminescence of plasma analytical method after being dissolved in hot chloroazotic acid, and the result is 50 quality %.

The Pt particle diameter of the platinum catalyst that obtains has been shown in the table 16.The particle diameter of Pt particulate uses the method for Scherrer by (motor system of science, the half peak breadth at (111) peak of the platinum that RAD-3C) obtains is estimated with the X-ray diffraction device.

The active carbon of the present invention regulation and other active carbon or carbon black relatively, although load the such high density of 50 quality %, also can obtain the particle diameter below the 2.0nm, thereby find out that obviously the Pt particle diameter is little, be excellent as carrier.

Table 16

Material with carbon element	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm
Material with carbon element	SBET m ²/g	S _micro/S _total	Micro-pore diameter nm	Oxygen content quality %	DBP oil absorption mL/100g	Pt particle diameter nm	Active carbon	2310	0.85	1.32	3.5	70	1.6

In argon gas stream, in this platinum catalyst, add 5%Nafion solution (ア Le De リッチ system) so that the quality of Nafion solid constituent is 2 times with respect to the quality of platinum catalyst, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring, so that the solid component concentration that platinum catalyst and Nafion lump together is 6 quality %, thereby make catalyst pulp.

In another container, put into the raw material of wood-charcoal material AA shown in the table 15, add butyl acetate, use the ultrasonic-wave crushing material with carbon element, thereby make raw material of wood-charcoal slip material so that the raw material of wood-charcoal material is 6 quality %.After each catalyst pulp of above-mentioned making and raw material of wood-charcoal slip material mixed with mass ratio 8:2, fully stir, make the catalyst layer slurry.

This catalyst layer slurry is coated in the microporous layers side of above-mentioned two kinds of gas diffusion layers respectively with sprayer, in 80 ℃ argon gas stream dry 1 hour, obtains two kinds of use in solid polymer fuel cell electrodes of the present invention.

In addition, be 0.10mg/cm according to the platinum use amount in the electrode ²Set conditions such as injection.The platinum use amount is obtained by its poor calculating by measuring the dry mass of spraying front and back electrode.

In addition, respectively intercept the electrode of the square size of two pieces of 2.5cm from the use in solid polymer fuel cell electrode that obtains, two pieces of electrodes with identical type clip dielectric film (Nafion112) so that catalyst layer contacts with dielectric film, under 130 ℃, stagnation pressure 0.625t, carry out hot pressing 3 minutes, thereby make MEA49,50.

The MEA that obtains is respectively charged in the fuel cell measurement mechanism, carries out battery performance and measure.

The battery performance measurement is to make between battery terminal voltage (be generally about 0.9V～1.0V) change to 0.2V interimly, measure the current density that flows through when voltage is 0.8V and 0.5V between battery terminal respectively from open circuit voltage.

Gas is to supply with pure hydrogen so that utilance is respectively 50% and 80% mode to negative electrode air supply, anode, uses the counterbalance valve that is arranged on the battery downstream that pressure is adjusted into 0.1MPa to air pressure separately.Battery temperature is set at 80 ℃, and the air of supply and pure hydrogen are to carry out bubbling in the distilled water of 80 ℃ and 90 ℃ in insulation respectively, thus humidification.

The MEA49 that obtains, 50 battery performance result have been shown in the table 17.Be provided with the current density excellence of MEA49,50 when the cell voltage of 0.8V, 0.5V of microporous layers.

Especially in the intermediate layer, use the water vapor adsorption amount as below the 100mL/g and also the ratio X/Y of DBP oil absorption X and nitrogen adsorption specific surface area Y be that the MEA49 of the carbon black A more than 1.0 has brought into play extremely excellent battery behavior.

Table 17

(embodiment 10)

Preparation carbon cloth (EC-CC1-060 of ElectroChem corporate system) is impregnated in and is diluted in 5% the teflon dispersion liquid, and is dry then, is warming up to 340 ℃ and make the gaseous diffusion fibrage again in argon gas stream.

In addition, in material with carbon element AC, the AD shown in the table 18, AE1g, add ethanol 99g respectively, pulverize carbon black, make dispersion liquid one time with ball mill.Then, the limit is stirred a dispersion liquid limit and is dripped 30% teflon dispersion liquid 0.833g bit by bit, makes the microporous layers slurry.

Use sprayer to be coated on the fibrolaminar face of gaseous diffusion of above-mentioned making in this slurry, in argon gas stream, after 80 ℃ of following dryings, be warming up to 340 ℃, make three kinds of gas diffusion layers that gaseous diffusion fibrage and microporous layers are laminated.

Table 18

The kind of material with carbon element	The pore volume mL/g that 2nm is following	Nitrogen adsorption specific surface area (Y) m ²/g	DBP oil absorption (X) mL/100g	X/Y	Water vapor adsorption amount mL/g
The kind of material with carbon element	The pore volume mL/g that 2nm is following	Nitrogen adsorption specific surface area (Y) m ²/g	DBP oil absorption (X) mL/100g	X/Y	Water vapor adsorption amount mL/g	AC	0.01	72	170	2.36	3.86
AD	0.05	227	219	0.96	59.8	AC	0.01	72	170	2.36	3.86
AD	0.05	227	219	0.96	59.8	AE	0.01	40	159	3.98	3.56
AF	0.39	1582	515	0.33	158	AE	0.01	40	159	3.98	3.56

In water, disperse under 50 ℃, to be incubated as the material with carbon element AF shown in the table 18 of catalyst carrier, add chloroplatinic acid aqueous solution and formalin while stir, obtain catalyst precarsor.

With this catalyst precarsor filtration, washing, drying, then at 100%H ₂Under 300 ℃, reduce in the air-flow and handled 3 hours, thus the platinum catalyst of 20 quality % platinum that has been modulated on the catalyst carrier material with carbon element load.

The platinum grain of the platinum catalyst that obtains directly is 1.8nm.The crystallite diameter uses the method for Scherrer by (motor system of science, the half peak breadth at (111) peak of the platinum that RAD-3C) obtains is estimated with the X-ray diffraction device.

In argon gas stream, in this catalyst, add 5%Nafion solution (ア Le De リッチ system) so that the quality of Nafion solid constituent is 2 times with respect to the quality of platinum catalyst, after stirring lightly, use the ultrasonic-wave crushing catalyst, add butyl acetate while stirring so that the solid component concentration that Pt catalyst and Nafion lump together is 6 quality %, thus the modulation catalyst slurry.

In another container, put into the raw material of wood-charcoal material AC shown in the table 18, add butyl acetate, use the ultrasonic-wave crushing material with carbon element, thereby make raw material of wood-charcoal slip material so that the raw material of wood-charcoal material is 6 quality %.

After each catalyst pulp of above-mentioned making and raw material of wood-charcoal slip material mixed with mass ratio 8:2, fully stir, make the catalyst layer slurry.

This catalyst layer slurry is coated in the microporous layers side of three kinds of above-mentioned gas diffusion layers respectively with sprayer, drying is 1 hour in 80 ℃ argon gas stream, thereby obtains to contain in catalyst layer the three kinds of use in solid polymer fuel cell electrodes of the present invention as the material with carbon element AC of catalyst carrier material with carbon element.

In addition, be 0.10mg/cm according to the platinum use amount in each electrode ²Set conditions such as injection.

The platinum use amount is obtained by its poor calculating by measuring the dry mass of spraying front and back electrode.

In addition, respectively intercept two pieces of sizes that 2.5cm is square by the use in solid polymer fuel cell electrode that obtains, two pieces of electrodes with identical type clip dielectric film (Nafion112) so that catalyst layer contacts with dielectric film, under 130 ℃, stagnation pressure 0.625t, carry out hot pressing 3 minutes, thereby make three kinds of MEA51～53.

The battery performance result of three kinds of MEA that obtain has been shown in the table 19.MEA consequently of the present invention has demonstrated excellent battery performance.

Wherein, in microporous layers, used the water vapor adsorption amount as below the 50mL/g and also the ratio X/Y of DBP oil absorption X and nitrogen adsorption specific surface area Y be that the MEA51 and 53 of material with carbon element AC, AE more than 1.5 has brought into play extremely excellent battery behavior.

Table 19

As mentioned above, excellence aspect the gaseous diffusion of the fuel cell that the catalyst layer of stipulating among the present invention is used for negative electrode at least in catalyst layer, electrical conductivity, proton conduction, the moisture management, and, can improve the utilance of catalyst component, reduce the noble metal use amounts such as platinum that are used for catalyst, promptly have the fuel cell that cost degradation and output characteristic improve concurrently so can provide.

In addition, according to the present invention, because it is suitable to be used for the characteristic of carbon black of gas diffusion layers, so carry out in to catalyst layer fully in the humidification, the evolving path of gas is difficult for the obstructions such as water droplet that produced, can show higher output characteristic.

Therefore, the present invention is big in industrial utilizability.

Claims

1, fuel cell, it comprises a pair of catalyst layer that accompanies the proton-conductive electrolyte film, it is characterized in that, at least the catalyst layer of negative electrode is by containing catalyst component, the mixture of electrolyte and material with carbon element constitutes, and described material with carbon element by load described catalyst component the catalyst carrier material with carbon element and do not have the gaseous diffusion material with carbon element of the described catalyst component of load to constitute, described catalyst carrier material with carbon element is that 90% o'clock water vapor adsorption amount is 50mL/g～1500mL/g 25 ℃ and relative humidity, and described gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity.

2, according to the fuel cell of claim 1 record, described catalyst carrier material with carbon element is an active carbon, utilizes BET to estimate the surface area SBET that obtains and satisfies SBET 〉=1500m ²/ g, and diameter is the surface area Smicro (m of the following micropore of 2nm ²/ g) with respect to total pore area Stotal (m ²/ g) ratio satisfies Smicro/Stotal 〉=0.5.

According to the fuel cell of claim 2 record, it is characterized in that 3, diameter is that the average diameter of the following micropore of 2nm is 0.7nm～1.5nm in the described active carbon.

4, according to the fuel cell of claim 2 or 3 records, it is characterized in that the oxygen content of described active carbon is below the 5 quality %.

5, according to the fuel cell of claim 1 record, diameter is that the following micropore volume of 2nm is more than the 0.1mL/g in the described catalyst carrier material with carbon element, and the DBP oil absorption of this catalyst carrier material with carbon element is more than the 300mL/100g.

6, according to the fuel cell of claim 5 record, it is characterized in that the specific area SBET that utilizes the BET method to obtain of described catalyst carrier material with carbon element is 500m ²More than/the g.

According to the fuel cell of any one record in the claim 1,2,3,5 and 6, it is characterized in that 7, the content of described gaseous diffusion material with carbon element in catalyst layer is 5 quality %～50 quality %.

According to the fuel cell of any one record in the claim 1,2,3,5 and 6, it is characterized in that 8, described gaseous diffusion material with carbon element is that 90% o'clock water vapor adsorption amount is 1mL/g～50mL/g 25 ℃ and relative humidity.

According to the fuel cell of any one record in the claim 1,2,3,5 and 6, it is characterized in that 9, described catalyst component contains the metal complex of N4 chelate type.

10, according to the fuel cell of claim 9 record, wherein said metal complex has the complex structure of N4 chelate type, and the N intratomic of central metal institute combination is the imines type more than at least two.

11, the fuel cell of putting down in writing according to claim 9, it is characterized in that the O-O bond length of the oxygen molecule that combines with the complex compound central metal in the metal complex that described metal complex calculates with the B3LYP Density functional method of counting and the adsorption structure of oxygen molecule is from for more than the 0.131nm.

12, according to the fuel cell of claim 11 record, the metal complex of wherein said N4 chelate type is one or both in following general formula 1 or the general formula 2,

General formula 1

Wherein, M is a metallic atom, R ¹-R ¹⁰Be hydrogen or substituting group;

General formula 2

Wherein, M is a metallic atom, R ¹¹-R ²⁴Be hydrogen or substituting group.

13, according to the fuel cell of claim 9 record, the complex compound central metal of wherein said metal complex is more than one the metal that is selected from the transition metal of periodic table V family, VI family, VII family or group VIII.

14, according to the fuel cell of claim 9 record, it is characterized in that,, also contain noble metal as described catalyst component.

15, gas diffusion electrode for fuel cell, it is characterized in that, be made of following part: the catalyst layer of the negative electrode at least of the fuel cell of any one record in the claim 1～14, what form at the opposition side of the face that contacts with the proton-conductive electrolyte film of this catalyst layer is the microporous layers of principal component and what form on this microporous layers is the gaseous diffusion fibrage of principal component with the fibrous carbon material with the carbon black, wherein, the carbon black of described microporous layers is that 90% o'clock water vapor adsorption amount is below the 100mL/g 25 ℃ and relative humidity.

16, according to the gas diffusion electrode for fuel cell of claim 15 record, it is characterized in that, as the DBP oil absorption XmL/100g and the nitrogen adsorption specific surface area Ym of the carbon black of the principal component of described microporous layers ²The ratio X/Y of/g is more than 1.