CN1550050A - Micro-structural flow field - Google Patents
Micro-structural flow field Download PDFInfo
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- CN1550050A CN1550050A CNA998151661A CN99815166A CN1550050A CN 1550050 A CN1550050 A CN 1550050A CN A998151661 A CNA998151661 A CN A998151661A CN 99815166 A CN99815166 A CN 99815166A CN 1550050 A CN1550050 A CN 1550050A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
A flow field for an electrochemical cell such as a fuel cell is provided, having micro-flow channels having a width or depth of less than 800 mu m, a pitch of less than 800 mu m, or a proportion of inter-channel land area of less than 25 %. The channels may further comprise micro-features within the channels. A flow field plate comprising the subject flow field is provided.
Description
Invention field
The present invention relates to the flow field of membrane electrode assembly in such as electro-chemical cells such as fuel cells.Flow field of the present invention comprises a large amount of microchannels, and these microchannels are preferably separated by the piston ring land characteristic body of same size and preferably have a micro structured feature.In fuel cell, flow field of the present invention has strengthened fuel distribution, has improved the moisture content manipulation, and has improved electricity and thermal diffusion.
Background of invention
United States Patent (USP) 5,108,849 relate to a kind of serpentine flow design of 7 passages, and in this design, 7 serpentine channels are arranged in parallel.This serpentine design make passage be the flow field movable part physical length 5-15 doubly.But this has but increased the pressure drop on the plate.Known serpentine flow is also tended to produce reactant consumption along passage, because of passage length and relatively short reactant residence time are restrained (spent gas of stagnating when one deck plays diffusion barrier and does the time spent), and swell (when the expansion of DCC material enters in the flow-field plate passage).In present theoretical research, Yi and Nguyen (Y.S.Yi and T.Nguyen, paper is referring to nineteen ninety-five, Proc.lst Internat.Symp.PEM fuel cell, the 66-75 page or leaf, the editor is S.Gottesfeld, G.Halpert and A.Landgrebe) also disclose, for the serpentine flow of classics, making reactant spread the degree of difficulty that runs under land area can greatly influence the maximum current density that can obtain from a given fuel cell.
McElroy (United States Patent (USP) 4,855,193), (paper is referring to nineteen ninety-five for C.Zawodzinski, M.S.Wilson and S.Gottesfeld for people such as Wilson (United States Patent (USP) 5798187) and Zawodzinski, Proc.lst Internat.Symp.PEM fuel cell, the 57-65 page or leaf, the editor is S.Gottesfeld, G.Halpert and A.Landgrebe) estimated the square situation of organizing the fluidic distributor of metallic sieve type of traditional serpentine flow design increase.These flow fields can comprise metallic steel silk fabrics or screen cloth, and wherein the metallic steel silk forms a series of coiling, tissue, curls or other contoured.The method has some shortcomings, comprises that reactant distribution is inhomogeneous, moisture content is handled problem and corrosion.
Equally, United States Patent (USP) 5,641,586 relate to a kind of double-layer structure, in this structure, be a porous layer cover one deck have the interdigitated fluid passage the layer on.
The invention summary
The invention provides a kind of improved flow field that is used for electro-chemical cell, this flow field comprises one or more microchannel, the degree of depth of passage or width (perhaps preferably both) be all less than 800 μ m, should be less than 650 μ m, be more preferably less than 250 μ m, be preferably between the 125 and 250 μ m.The spacing of these microchannels should be more preferably less than 250 μ m less than 650 μ m less than 800 μ m, is preferably between the 125 and 250 μ m.Microchannel of the present invention also can comprise many little characteristic bodies in passage, degree of depth of characteristic body and width dimensions should be more preferably less than 20% less than 50% less than 80% of channel depth and width dimensions slightly for these.The size of little characteristic body should be more preferably less than 100 μ m less than 160 μ m.Can have the degree of depth or width reaches the passage of 3mm with the flow field of little characteristic body, and still keep advantage of the present invention.In a preferred embodiment, what these microchannels were used is the parallel pattern of a kind of height, can be surrounded by many interconnecting parts or branching-point in this pattern.
In yet another aspect, the invention provides the flow-field plate that comprises flow field, microchannel of the present invention.
In yet another aspect, the invention provides the diffuser-current-collector (DCC) that comprises flow field, microchannel of the present invention.
In yet another aspect, the invention provides the fuel cell that comprises flow field, microchannel of the present invention, perhaps comprise the DCC in flow field, microchannel of the present invention.
Flow field of the present invention can obtain more uniform reactant distribution, more uniform pressure distribution by using additional littler characteristic body and the highly parallel microfluid passage of band, has improved the moisture content in the fuel cell stack and has handled, and has improved performance.In addition, flow field of the present invention can reduce the thickness of flow-field plate and/or DCC, the weight that can reduce to pile up, volume, cost and interior resistance.
As used in this article,
" diffuser-current-collector " or " DCC " is meant adjacent with catalyst active sites in an electro-chemical cell layer, can be for reactant and product and current delivery to these active sites with leave these active sites, described layer is preferably the electric conducting material of porous;
" highly parallel " is meant and comprises many elements with identical function, specifically be meant to have the passage that many and same inlet links to each other with same outlet.
" no branch aspect ratio " is the ratio of length with its hydraulic radius of no branch channel section;
" hydraulic radius " be channel cross-sectional area divided by perimeter of section, for example the hydraulic radius of circular channel is 1/4 of its diameter;
" flow field " is meant parts of electro-chemical cell, and it allows such as fluids such as reactant gas and waste gas and liquid discrepancy conversion zone.
An advantage of the invention is provides a kind of flow field, it by improve water and reaction gas object distribution improve fuel cell performance.
Summary of drawings
Fig. 1 is the voltage of three kinds of fuel cell polarization curves of the present invention and the curve chart of current density.
Fig. 2 is two kinds of fuel cells of the present invention and a kind of voltage and current density curve chart of relatively using the fuel cell polarization curve.
Fig. 3 is a kind of fuel cell of the present invention and a kind of voltage and current density curve chart of relatively using the fuel cell polarization curve.
Fig. 4 is the voltage of three kinds of fuel cell polarization curves of the present invention and the curve chart of current density.
Fig. 5 is two kinds of fuel cells of the present invention and a kind of voltage of the polarization curve of relatively using fuel cell and the curve chart of current density.
The detailed description of preferred embodiment
The present invention is for providing a kind of improved flow field such as electro-chemical cells such as fuel cells.Fuel cell is to utilize fuel and oxidant to produce the electro-chemical cell of electric current.These two kinds of chemical reactants, i.e. fuel and oxidant react containing on two electrodes that separate of catalyst respectively.Ion exchange element is placed between the electrode, is used to prevent that two kinds of reactants from directly reacting, and conducting ion.The combination of ion exchange element and electrode is commonly called " membrane electrode assembly " or MEA.In traditional fuel cell, MEA is between the conductivity demarcation strip of two rigidity, every demarcation strip has engraving, a milling at least on the surface of MEA or the fluid passage that is molded into is a groove 3 at it, and these demarcation strips also are called flow-field plate, are generally made by graphite.Fluid passage in these two demarcation strips is with fuel and oxidant lead respectively separately electrode, the i.e. negative electrode of the anode of fuel-side and oxidant side.In a cell stacks, demarcation strip in series is electrically connected, and provides conductive path between the electrode of adjacent cell.
The advantage of MEA is to work under approximately big air pressure condition.But, the flow field that the design of lower work pressure request is better, so as to eliminate in reactant distribution under the low pressure drop situation inhomogeneous and under the low pressure drop condition water problem such as from passage, remove.
The Field Characteristics thing that flow field, microchannel of the present invention uses size to dwindle, the moisture content of interpolation is handled the surface, and highly parallel flow field pattern.The inventor finds, can make the horizontal fluid passage of reduced size basically, keeps low-down pressure drop simultaneously.The degree of depth of passage is less than 800 μ m, should be less than 650 μ m, and better less than 250 μ m, but be preferably between the 125 and 250 μ m.Width of channel is less than 800 μ m, should be less than 650 μ m, and better less than 250 μ m, but be preferably between the 125 and 250 μ m.If implement, be 500cm for active area by the flow field, microchannel
2MEA, the parallel channels of width between 125-250 μ m will still have the pressure drop of tens kPa.Bigger battery can be divided into a plurality of subdivisions, to keep lower pressure drop.
In a preferable embodiment, these microchannels are height pattern parallel.These patterns can comprise interconnecting parts or scolus.This class pattern comprises parallel lines, oblique fracture upper thread and the grid line of passage.Microchannel can have any cross sectional shape that required fluid transmission can be provided, and preferably its shape is duplicated easily.Best, conduit wall tilts, and feasible channel width from the teeth outwards is greater than the width of channel bottom.Wall is tilted shape can make arrangement of passages tight, and can make interchannel land area narrow down to zero the limit theoretically, and for example, at this moment passage only is that the position of piston ring land is adjacent at the peak.
In a preferable embodiment, these microchannels lean on very closely, and spacing is less than 800 μ m, should be less than 650 μ m, and better less than 250 μ m, but be preferably between the 125 and 250 μ m.The spacing here is the minimum range between the directly corresponding position of adjacency channel, the distance on for example distance at peak and peak, or limit and limit.
Find also that in addition adding littler characteristic body (little characteristic body) in channel bottom can provide new mechanism for removing of water, and can improve and the electrically contacting and thermo-contact of diffuser.This slightly the degree of depth of characteristic body and width dimensions less than 80% of the degree of depth of passage and width, should less than its 50%, better less than 20%.The size of little characteristic body should be less than 160 μ m, better less than 100 μ m.The degree of depth and the width that have been found that the passage in little characterization flow field can reach 3mm, still can keep advantage of the present invention.
Flow field of the present invention can form with any suitable method, and described method comprises the United States Patent (USP) 5,728,446 of authorizing people such as Johnston, and the U.S. Patent application 09/099,269 that awaits the reply, and their full content is with reference to being incorporated into this.These two patent documentation imaginations are used a kind of liquid management film, and film comprises many parallel channels, has embedded in each channel bottom to have the more accurate thin groove of yardstick in fact.Can think that these accessory channels can make water preferential condensation in the extremely thin film of channel bottom.The intersection on two surfaces of little groove is to be used for adsorbing the active site that becomes liquid film from steam, and it is starting, and liquid film is along the growth of little groove length continuously, and liquid is subjected to the promotion (this barometric gradient depends on thickness gradient and capillary pressure gradient) of the non-intersect barometric gradient of ambient pressure gesture on the liquid film.Then, the capillary pressure gradient moves to channel end with this film, is very effective path of the generation of distribution again of water.In addition, undersized passage impels and form drop on passage, and this helps to remove effectively moisture content from passage.On the contrary, bigger passage does not utilize this moisture content to remove behavior, because this behavior requires to produce momentum transfer by friction between mobile gas stream and liquid layer.This efficient that has just caused liquid to be removed is lower, and catalyst utilization is relatively poor.The inventor has been found that the method for the application of the invention, can water be moved through to have the passage of the narrower degree of depth or width, and these passages almost do not have hydraulic pressure to fall, thereby make reactant can arrive the active region of entire cell.
Another advantage of the present invention is to distribute mechanical support better, and reduces " protuberance ", and wherein " protuberance " is that the DCC material expands to the result in the flow field.When the span of every fluid passage reduces, the compression stress that acts on the DCC will be distributed on the uniform more area.When the size of each no Support is dwindled, the protuberance degree will reduce equally.For softer DCC material, reduce protuberance trend and be even more important.
When the lateral dimension of piston ring land characteristic body dwindles, just dwindled reacting gas for arrive all useful catalysts playgrounds must land area below by lateral separation.In addition, dwindle channel size and can dwindle the lateral separation that electronics must pass through from the active region to the land area.Less piston ring land size can be improved distribution of gas, perhaps has an opportunity to reduce the gross thickness of DCC, because reduced the needs (referring to the example 5 of back) that gas transverse diffuses through DCC.Because the overall transmission rate by DCC is relevant with its thickness, so the diffusion rate of reactant and product water has all improved.This has further reduced weight, volume, cost and the resistance of DCC layer.
An advantage of flow-field plate of the present invention is that it allows to use thinner DCC layer.(referring to the example 5 of back).This may be that part is because can obtain less land area size and less spacing according to the present invention.This just may reduce the thickness of DCC, keeps the best land width and the ratio of DCC thickness simultaneously.Use flow-field plate of the present invention effective MEA can with thickness less than 50 μ m or even thickness make less than the DCC layer of 25 μ m.
The diffusion property that improves can be useful on the two the diffusion path length of transmission of the transmission of electricity and gas and express.Must arrive the land area of flow-field plate by the electric current of DCC conduction, just can be transmitted in the circuit of fuel cell.Therefore, narrower channel width can shorten circuit length, and therefore improves conductivity.Similarly, must arrive a passage of flow-field plate by the gas of DCC conduction, therefore narrower land area can shorten the length of the gas transmission path that leads to this passage, thus transport gas better, although may have bigger resistance.Can optimize land width and channel width, so that obtain best mass distribution and CURRENT DISTRIBUTION.
Preferred embodiment of the present invention is reduced to the ratio that resistance will rise to unacceptable degree with the ratio of land area.The land area in flow field of the present invention should be less than 50% of fuel cell active region.Better less than 25%, better less than 20%, 15% and even 10%, preferably less than 5%.The passage that these embodiments with less land area ratio can adopt wall to tilt according to the present invention is realized.If use than major path, so above-mentioned situation is impossible, the protuberance problem will inevitably occur.
Therefore, preferable embodiment of the present invention distribution, the electricity that can improve mechanical force simultaneously led and distribution of gas.
The minimum of passage does not have branch aspect ratio (length/hydraulic radius) and is preferably 5: 1, better surpasses about 10: 1, even surpasses 100: 1, preferably at least about 1000: 1.On the top, no branch aspect ratio can be infinitely great, but be generally less than about 1,000,000: 1.
Flow field of the present invention is preferably in the flow-field plate and implements.Flow-field plate use make such as electric conducting materials such as metals comparatively favourable.Another kind method is to use the material with carbon element of conduction.In addition, can electroplate material, sputter or with damp process, vacuum method or any suitable method coated with conductive layer.
As a kind of possible alternative, also can be on diffuser-current-collector (DCC) layer of MEA, cutting forms or otherwise forms flow field of the present invention.Like this a slice monolayer material just can play a part DCC and flow field the two.The present invention can be used for structure such as electro-chemical cells such as fuel cells.
Below some examples further illustrate many purposes of the present invention and advantage, but concrete material and the quantity thereof used in these examples also have other condition and details should not be interpreted into inadequately the present invention are provided constraints.
Example
Flow field and end plate
In following examples, the flow field insert is installed in the end plate that stainless steel 316 makes.The machining accuracy of end plate is very high, and it has many rectangular enclosures, is used to hold flow field insert and fluid passage, and these fluid passages are that directing reaction gas commutes the flow field insert.Flow field itself is according to United States Patent (USP) 5,728, and the method for 446 described examples 1 as building material, forms Ni from corresponding negative electroforming, and the content of described patent is with reference to being incorporated into this.For anode and negative electrode, below the flow field structure that uses in all examples all be parallel, and corresponding to the pattern 2 of table 1 in ' 446 patents.This pattern comprises many parallel wire grooves, groove depth 635 μ m, and spacing is 330 μ m, each cell wall tilts 5 ° with respect to vertical direction.The flow field insert is to cut into square (22.36mm * 22.36mm), be 5cm so that cooperate active region used in the following example from bigger electroforming sheet material
2MEA.
Comparative example uses the active region that can buy on the market to be 5cm
2Battery, it has identical anode and negative electrode parallel flow field, this flow field is formed by graphite end plate (the fuel cell technology company in New Mexico Albuquerque city) milling.The flow field comprises 13 square kerves, and 790 μ m are wide, and 790 μ m are dark, and 2.10mm is long.Land area is that 790 μ m are wide.These flow fields link to each other by parallel square kerve at its openend, the wide 1.57mm of these kerves, dark 1.57 μ m, long 2.10mm.
Catalyst and membrane electrode assembly (MEA)
Below the explanation of some examples with pack into several distinct methods of membrane electrode assembly of catalyst, as described below, used catalyst is called dispersed catalyst, nano-structured calalyst and gradient catalyst.
In following each example, the ion-conductive membranes (ICM) that is used to make MEA is Nafion
TMFilm (DE can buy to the Aldrich in the electrochemical company in Woburn city, MA state and Milwaukee city, WI state chemistry limited company for Du Pont's chemical products, Wilmington), the polymer of this (perfluorinated) sulfonic acid functional that is fluoridized.Unless otherwise noted, ICM is Nafion 112 films, and this film is a uniaxial tension, and thickness is reduced to 25 microns from 50 microns.
In following each example, electrode pad layer or diffuser-current-collector (DCC) are the thick DS of 0.45mm or 0.42mm (two-sided) ELAT
TMThe electrode pad material.
Be prepared as follows the MEA that two sides (D-D) all has dispersed catalyst: with a kind of ink coats ELAT
TMElectrode pad material (400 microns), described printing ink comprises 0.67g Pt/C and 0.7g glycerine, and they are suspended in the 5wt%Nafion that contains that weight is 6.7g
TMIn 1000 the iso-propanol/water mixture solution, then in vacuum furnace, with 93 ℃ of dryings of gasket material 10 minutes, on DCC, form one deck catalyst.The 5cm of catalyst will be covered with
2The DCC square plate is placed on the Nafion of drawn
TMThe two sides of film.Then, the center of this assembly of gained is placed applied 566 micron thickness (altogether) Teflon
TMGlass fibre packing ring (the Furon Co., Ltd in CT state New Haven city, CHR department) 5cm
2Square opening in, this square opening is cut and is matched with catalyst area.The polyimides of a slice 50 micron thickness, 7.6cm * 7.6cm is placed on its each face.The gained assembly is placed between two billets, and (the Carver limited company in Wabash city, IN state) suppresses under 135 ℃ of temperature and 10Mpa pressure with the Carver laboratory press.Divest polyimide piece, stay the MEA of 5 layers of head, have dispersed catalyst to be positioned on two surface.With 30.5% degree of compression above-mentioned MEA is contained in the fuel cell test frame.Use the original, uncompressed material as reference.
Be prepared as follows the MEA of nano-structured calalyst: according to United States Patent (USP) 5,338,430 described prepared are as the microstructured bodies of catalyst support member, and the content of described patent is with reference to being incorporated into this.With United States Patent (USP) 4,812,352 and 5,039,561 described technology by thermal evaporation and vacuum annealing, are made and are positioned on the polyimide substrate the red film of nanostructure De perylene, be C.I. pigment red 149 or N, N '-two (3,5-xylyl) perylene-3,4:9, the film of two (dicarboximide) (PR149, the American Hoechst Co., Ltds in Somerset city, NJ state) of 10-.After its deposition and annealing, form the bigger crystal structure of high directed aspect ratio, its controlled length is about the 0.5-2 micron, width is about the 0.03-0.05 micron, overtoping whisker number density (aerial number density) is approximately 30 whiskers on every square micron, and these whisker orientations are substantially perpendicular to polyimide substrate.Metallic catalyst with nano particle applies these micro-structural catalyst support members, and it is added is pressed into ion-conductive membranes (ICM), divests polyimide substrate afterwards, stays the nano-structured calalyst strutting piece and is embedded among the ICM.
Then, be prepared as follows the MEA that has nanostructured elements on two electrode surfaces: making the active region area with the nip roiler rolling is 5cm
2Three layers of MEA.Two vapour are positioned at the microtexture catalyst transmit 5cm on the polyimide substrate (MCTS)
2Square nanostructured elements (one is used for anode, and another is used for negative electrode) is placed on the as above 7.6cm * 7.6cm Nafion of preparation respectively
TMIt is to prepare as the method that the application 09/369,619 of awaiting the reply is jointly described that polyimide substrate is transmitted on the two sides at the center of film, this microtexture catalyst, and the content of this patent is with reference to being incorporated into this.Anode catalyst is made up of Pt and Pu, and they press 0.22mg/cm
2Sputter on the MCTS whisker.Cathod catalyst is made up of Pt, and it is with 0.28mg/cm
2Sputter on the MCTS whisker.With the polyimide piece of 50 micron thickness, 7.6cm * 7.6cm and the coating scraps of paper of 20cm * 28cm (high-quality ink-jet glossy paper, Item#HP C3836A, the Hewlett-Packard limited company in Palo Alto city, California) be placed on respectively by the substrate/Nafion that has applied catalyst
TMOn the two sides of the sandwich structure that this three of substrate of/coated catalysts is constituted, paper glossiness that towards the substrate that scribbles catalyst.The assembly of gained under the condition of 135 ℃ and 6.9Mpa, with 0.33m/ minute speed, is rolled between two steel rolls.Divest paper and original 5cm
2Polyimide substrate stays the Nafion that is fixed with catalyst on the surface
TMFilm.In order to prepare the MEA of 5 layers of head, with thick DS (two-sided) ELAT of 0.45mm
TMThe electrode pad material covers on the ICM of above-mentioned three layers of head.Before fixing, sputter at DS ELAT with the thick Pt of 200
TMElectrode pad material and 3 layers of ICM are on the two.The center of this assembly of gained is placed the Teflon that has applied 200 micron thickness
TMGlass fibre packing ring (the CHR department of Furon company in CT state New Haven city) on 5cm
2Square opening in, this square opening is cut and is matched with catalyst area.Polyimide piece 50 micron thickness, 7.6cm * 7.6cm is placed on its each face.The gained assembly is placed between two billets, under 135 ℃ and 10Mpa condition, suppresses with Carver laboratory press (the Carver limited company in Wabash city, IN state).Divest polyimide piece, on two electrode surfaces, stay 5 layers of MEA with nanostructured elements.With 38.5% degree of compression above-mentioned MEA is contained in the fuel cell test frame, uses the original, uncompressed material as reference.
On an electrode surface, have nanostructured elements, gradient catalyst (N-G) is arranged and the MEA that has nano-structured calalyst and dispersed catalyst on another surface is called as it.These MEA are the U.S. Patent applications 09/312 that await the reply jointly, 6 layers of structure described in 514 (the content reference of this patent is in conjunction with these), described 6 layers of structure comprise an anode DCC layer, an anode catalyst layer, a film electrolyte, two cathode catalyst layers and a negative electrode DCC layer.
Be prepared as follows gradient MEA (N-G): with two 5cm that nanostructured elements is arranged
2Square, MCTS polyimide substrate (is used for anode, and is used for negative electrode) is placed on the as above 7.6cm * 7.6cmNafion of preparation respectively
TMOn the two sides at the center of film.Anode catalyst is made up of Pt and Pu, and they press 0.22mg/cm
2Amount sputter on the MCTS whisker.Cathod catalyst is made up of Pt, and it is with 0.28mg/cm
2Amount sputter on the MCTS whisker.The polyimide piece of 50 micron thickness, 7.6cm * 7.6cm is placed on by the substrate/Nafion/ that has applied catalyst applied on two faces of the sandwich structure that this three of substrate of catalyst constituted.The assembly of this gained under 135 ℃ of temperature and 6.9Mpa pressure, with 0.33 meter/minute speed, is rolled between two steel rolls.Then, divest 5cm
2Original polyimide substrate, stay the Nafion that is fixed with catalyst on the surface
TMFilm.Then, the target face adds one deck dispersed catalyst.With a kind of ink coats DS ELAT
TMElectrode pad material (420 microns), described printing ink comprises 0.67g Pt/C and 0.7g glycerine, and they are dispersed in the 5wt%Nafion that contains that weight is 6.7g
TMIn 1000 the iso-propanol/water mixture solution, then in vacuum furnace,, on DCC, form one deck catalyst with 93 ℃ of dryings of gasket material 10 minutes.
With the thick DS ELAT that is covered with catalyst of 0.42mm
TMThe electrode pad material covers on the cathode plane of film of three layers of head of catalyst, with the DS ELAT of the thick catalyst-free of 0.51mm
TMCover on the anode surface of this film.Before covering, at anode (catalyst-free) face, with the glycerite that contains 4%Nafion 1100E.W., with wetting this ELAT of the amount of every square centimeter of 0.03mg Nafion
TMThe electrode pad material.Then, the center of assembly is placed this of gained and applied 200 micron thickness Teflon
TMGlass fibre packing ring (the CHR department of Furon company in CT state New Haven city) on 5cm
2Square opening in, this square opening is cut and is matched with catalyst area.Polyimide piece 50 micron thickness, 7.6cm * 7.6cm is placed on its each face.This assembly is placed between two billets, and (the Carver limited company in Wabash city, IN state) suppresses under 135 ℃ of temperature and 10Mpa pressure with the Carver laboratory press.Then, divest polyimide piece, on an electrode surface, stay 6 layer MEAs, on another surface, stay nano-structured calalyst and dispersed catalyst with nanostructured elements.
Thin DCC MEA
As described below, with the thick DCC material of 23 μ m and on two surface the way of dispersed catalyst make the thin DCC MEA (tD-Dt) that uses in the example 5: the suspension in the isopropyl alcohol aqueous solution of 6.7g applies ELAT with 0.67g Pd/C catalyst and 0.7g glycerine
TMElectrode pad material (approximately 0.4mm thick), then in vacuum drying oven with 93 ℃ of dryings of this gasket material 10 minutes, on DCC, form one deck catalyst.With the glycerite that contains 4%Nafion 1100E.W., with the wetting above-mentioned ELAT that catalyst is arranged of the amount of every square centimeter of 0.03mg Nafion
TMThe cathode plane of electrode pad material and anode surface.With 5cm
2The square DCC that catalyst is arranged and handle through Nafion is placed on each face of the Nafion that is stretched 112 films.Then, the center of this assembly of gained is placed applied the thick Teflon of 0.5mm
TMGlass fibre packing ring (the CHR department of Furon company in CT state New Haven city) on 5cm
2Square opening in, this square opening is cut and is matched with catalyst area, and polyimide piece 50 micron thickness, 7.6cm * 7.6cm is placed on its each face upside.This assembly is placed between two billets, uses Carver laboratory press (the Carver limited company in Wabash city, IN state) in 5Mpa pressure and 105 ℃ of temperatures systems.Divest polyimide piece.Then, also divest carbon cloth, the Teflon coating that stays internal layer carbon/ELAT is as the DCC thin layer.Discovery is necessary this thin layer of highly extruding, so that obtain gratifying the contact between the flow field of DCC and micro-structural.With the packing ring of 23 μ m, promptly allowing DCC thickness is the packing ring of 23 μ m, and above-mentioned MEA (tD-Dt) is contained in the test battery.
The test battery process
With the 360A testboard of buying from Alguquerque city, NM state fuel cell technology limited company, with the flow field end plate of above-mentioned micro-structural or relatively the end plate of usefulness test MEA.Each bolt to testing jig applies a torque to 13.8Nm.Testboard comprises a variable electronic load, and anode that separates and cathode gas treatment system are used to control air-flow, pressure and humidity.Electronic load and air-flow are by computer control.By gas stream is injected water vapour, come the gas stream of humidification anode and negative electrode.Enter the current of steaming plant by measurement, measure add the amount of water vapour.Under the following test parameter that provides, the polarization curve of record fuel cell.
Example 1
Compare two D-D type MEA, one of them uses the flow field end plate of micro-structural of the present invention, and another uses the relatively end plate of usefulness.
Obtain the fuel cell polarization curve under following test parameter: anodic gas is a hydrogen, and cathode gas is an air, and electrode area is 5cm
2Battery compression about 30%; Battery temperature is 65 ℃ or 70 ℃; Anodic gas pressure is 0.1MPa; The anodic gas flow is 100 standard cc/min; The anode humidification is equivalent to 2 * or 4 * in the saturation of this temperature; Cathode gas pressure is 0.1MPa; The negative electrode flow is 300 standard cc/min; The negative electrode humidification is equivalent to 0.75 *, 1 *, or 2 * in the saturation of this temperature.Each fuel cell is reached under 65 ℃ of conditions of work under the condition at hydrogen and air stream.At first night battery is adjusted, begin test procedure then.Measure following variable: anode pressure, anode gas flow, cathode pressure, cathode flame and battery temperature.
Table I has been provided by the maximum that obtains under these results' the optimum condition at 0.3V and providing (being transmitted restriction) electric current:
Table I
| The flow field type | Imax | The anode humidification | The negative electrode humidification | Battery temperature |
| Micro-structural | 1.289A/cm 2 | 4 * saturation | 2 * saturation | 65℃ |
| Usefulness relatively | 0.661A/cm 2 | 4 * |
1 * saturation | 70℃ |
Observe the maximum current that lower working temperature and higher humidity can reduce battery.Therefore, show that micro-structural of the present invention flow field can provide outstanding moisture content to handle under the situation that fluid water seriously surpasses in battery.
Example II
Carried out three experiments under different pressure, D-D type MEA and micro-structural flow field end plate of the present invention are all used in all experiments.
Experiment condition: MEA type: D-D; Reactant: H
2/ air; Battery compression is approximately 30%; Flow is 0.1/0.3SLM; Pressure: 0.1MPa (curve A), 0.15MPa (curve B), 0.2MPa (curve C); Battery temperature is 70 ℃; Anode is 4 * saturation; Negative electrode is 1 * saturation; The parallel flow field of micro-structural.Fig. 1 shows the polarization curve of these three experiments.Use the MEA of flow field end plate of the present invention in the certain pressure scope, to show good performance.
Example III
Under different pressures, experimentize, compare two kinds of D-D type MEA, a kind of flow field end plate of using micro-structural of the present invention, the another kind of use relatively used end plate.
Experiment condition: MEA type: D-D; Reactant: H
2/ air; Flow is 0.1/0.3SLM; Pressure: 0.1MPa (Fig. 2), 0.15MPa (Fig. 3); Battery temperature is 70 ℃; Anode is 4 * saturation; Negative electrode is 1 * saturation.The battery compression of all experiments all is 30.55%, but the battery compression of curve C is 33.8% among Fig. 2.
Fig. 2 and Fig. 3 show, the performance (curve B and C) with the D-D MEA in micro-structural flow field is better than having the performance (curve A) of the identical MEA in standard flow field.
In addition, observe also that to be used for standard parallel flow field and best battery compression size based on the MEA of ELAT be not the optimal compression that is used to have the identical MEA in micro-structural flow field.As a result, the increase (Fig. 2, curve C) of finding battery compression will further improve battery performance.
Therefore, show under this routine condition, and relatively compare micro-structural of the present invention flow field more performance can be provided with the flow field.
Example IV
Experimentize with micro-structural flow field end plate of the present invention, relatively the performance of three types MEA (D-D, N-N, and N-G).
Three kinds of dissimilar MEA that Fig. 4 explanation has the micro-structural flow field have good performance.Listed the condition of work of these MEA and condition of work separately: D-D (curve A) thereof below: battery compression is approximately 30%; H
2/ air, 0.1MPa, 0.1/0.3SLM, battery temperature are 65 ℃, humidification is 4 */1 *.The condition of work of N-N (curve B): H
2/ air, 0.1MPa, 0.1/0.3SLM, battery temperature are 70 ℃, humidification is 2 */0.75 *.The condition of work of N-G (curve C): H
2/ air, 0.1MPa, 0.1/0.3SLM, battery temperature are 70 ℃, humidification is 2 */1 *.Select condition of work, so that every kind of MEA obtains optimum performance under ambient pressure.Next all shows good performance to the MEA of use flow-field plate of the present invention in various types of catalyst situations.
Example V
Experimentize with tD-Dt type MEA, use the flow field end plate of micro-structural of the present invention earlier, use the relatively end plate of usefulness then, and then use the flow field end plate of micro-structural with DCC thin layer.
At first MEA is adjusted with the parallel flow field of micro-structural.Experiment condition is as follows: battery compression is approximately 30%; MEA type: D-D, the thick DCC of 23 μ m, reactant: H
2/ air, flow are 0.1/0.3SLM, and pressure is 0.1MPa, and battery temperature is 65 ℃, and anode is 2 * saturation, and negative electrode is 2 * saturation.After the phase of adjusting finishes, recording curve A.Then, open battery, flow-field plate is changed into the concurrent flow field plate of standard.Test battery under identical condition of work and compression degree (curve B).Then, battery is turned back to the state of micro-structural parallel flow field, and test again, confirm that MEA does not damage (curve C) between the commutation period of flow field.
Therefore, shown under this routine condition, and relatively compared micro-structural of the present invention flow field more performance can be provided, and can produce thinner MEA with the flow field.
For those skilled in the art, do not depart from the scope of the present invention and spirit is carried out various variations and change is conspicuous to the present invention, and should be appreciated that the present invention is not limited to above-mentioned illustrative embodiment.All publications and patent all reference are combined in this paper invention, just as if each publication or patent in this article all will be with reference to being incorporated at this by concrete also pointing out individually.
Claims (30)
1. a flow field is characterized in that, comprises one or more passages, and the degree of depth of described passage is less than 800 μ m, and width is less than 800 μ m.
2. a flow field is characterized in that, comprises a plurality of passages, and channel pitch is less than 800 μ m.
3. a flow field is characterized in that, it has an active region, and this active region comprises one or more passages, and described passage is separated by land area, and land area is less than 20% of active region in the flow field.
4. flow field as claimed in claim 2 is characterized in that, the degree of depth of described passage is less than 800 μ m, and width is less than 800 μ m.
5. flow field as claimed in claim 3 is characterized in that, the degree of depth of described passage is less than 800 μ m, and width is less than 800 μ m.
6. flow field as claimed in claim 2 is characterized in that, described flow field has an active region, and described active region comprises a plurality of passages that separated by land area, and land area is less than 25% of active region in the flow field.
7. flow field as claimed in claim 1 is characterized in that described flow field comprises one or more passages, and described channel depth is less than 650 μ m, and channel width is less than 650 μ m.
8. flow field as claimed in claim 1 is characterized in that described flow field comprises one or more passages, and described channel depth is less than 250 μ m, and channel width is less than 250 μ m.
9. flow field as claimed in claim 2 is characterized in that, comprises a plurality of passages, and the spacing of described passage is less than 650 μ m.
10. flow field as claimed in claim 2 is characterized in that, comprises a plurality of passages, and the spacing of described passage is less than 250 μ m.
11. flow field as claimed in claim 3 is characterized in that, land area is less than 15% of active region in the flow field.
12. flow field as claimed in claim 3 is characterized in that, land area is less than 5% of active region in the flow field.
13. a flow-field plate is characterized in that, comprises flow field as claimed in claim 1.
14. flow-field plate as claimed in claim 13 is characterized in that, its thickness is 1mm or littler.
15. a flow-field plate is characterized in that, comprises flow field as claimed in claim 6.
16. flow-field plate as claimed in claim 15 is characterized in that, its thickness is 1mm or littler.
17. a flow field is characterized in that it comprises one or more passages, the degree of depth of described passage is less than 3mm, and width is less than 3mm, and described passage also comprises a characteristic body slightly, the degree of depth of described little characteristic body is less than 80% of described channel depth, and width is less than 80% of described channel width.
18. flow field as claimed in claim 17 is characterized in that, the degree of depth of described little characteristic body is less than 50% of described channel depth, and width is less than 50% of described channel width.
19. flow field as claimed in claim 18 is characterized in that, the degree of depth of described little characteristic body is less than 20% of described channel depth, and width is less than 20% of described channel width.
20. flow-field plate that comprises the described flow field of claim 17.
21. flow-field plate as claimed in claim 20 is characterized in that, its thickness is 1mm or littler.
22. a fuel cell is characterized in that, comprises flow-field plate as claimed in claim 13.
23. a fuel cell is characterized in that, comprises flow-field plate as claimed in claim 15.
24. a fuel cell is characterized in that, comprises flow-field plate as claimed in claim 20.
25. fuel cell as claimed in claim 22 is characterized in that, described fuel cell comprises the DCC layer of thickness less than 25 μ m.
26. fuel cell as claimed in claim 23 is characterized in that, described fuel cell comprises the DCC layer of thickness less than 25 μ m.
27. fuel cell as claimed in claim 24 is characterized in that, described fuel cell comprises the DCC layer of thickness less than 25 μ m.
28. a diffuser-current-collector (DCC) is characterized in that, comprises flow field as claimed in claim 1.
29. a diffuser-current-collector (DCC) is characterized in that, comprises flow field as claimed in claim 6.
30. a diffuser-current-collector (DCC) is characterized in that, comprises flow field as claimed in claim 17.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1999/025401 WO2000026981A2 (en) | 1998-10-29 | 1999-10-29 | Microstructured flow fields |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1550050A true CN1550050A (en) | 2004-11-24 |
Family
ID=34374791
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA998151661A Pending CN1550050A (en) | 1999-10-29 | 1999-10-29 | Micro-structural flow field |
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| Country | Link |
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| CN (1) | CN1550050A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8277986B2 (en) | 2007-07-02 | 2012-10-02 | GM Global Technology Operations LLC | Bipolar plate with microgrooves for improved water transport |
| CN112829486A (en) * | 2021-01-22 | 2021-05-25 | 中汽创智科技有限公司 | Printing slurry, bipolar plate flow field using same and processing method thereof |
-
1999
- 1999-10-29 CN CNA998151661A patent/CN1550050A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8277986B2 (en) | 2007-07-02 | 2012-10-02 | GM Global Technology Operations LLC | Bipolar plate with microgrooves for improved water transport |
| CN112829486A (en) * | 2021-01-22 | 2021-05-25 | 中汽创智科技有限公司 | Printing slurry, bipolar plate flow field using same and processing method thereof |
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