Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
  • H01M8/0263—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant having meandering or serpentine paths
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
  • H01M8/0265—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant the reactant or coolant channels having varying cross sections
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
  • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
  • H01M8/04156—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal
  • H01M8/04179—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal by purging or increasing flow or pressure of reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2457—Grouping of fuel cells, e.g. stacking of fuel cells with both reactants being gaseous or vaporised
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2465—Details of groupings of fuel cells
  • H01M8/2484—Details of groupings of fuel cells characterised by external manifolds
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
  • H01M8/026—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant characterised by grooves, e.g. their pitch or depth
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the following invention relates to a fuel cell where the fuel is hydrogen and the oxidant is oxygen . It is essentially characterised by comprehending : one hydrogen diffusion plate who forms , together with the MEA - Membrane Electrode Assembly - a tight chamber allowing the operation under a dead-ended, fixed pressure configuration; an air diffusion plate with diffusion channels drawn perpendicularly as to form an intertwined grid allowing a natural air feeding ; the axial application and use of a small fan over the cell or stack allowing the reinforcement of the air flow according to operational requisites .
• Hydrogen- fuel cells' basic principles Hydrogen-fuel cells ' basic principles are widely spread today .
• a fuel cell is an electrochemical device where a reductive reagent reacts with an oxidant one forming electricity, heat and water .
• the typical fuel supplied to a PEM (Proton Exchange Membrane , or Polymer Electrolyte Membrane) fuel cell is hydrogen, and usually the oxidant is oxygen from the air .
• PEM Proton Exchange Membrane
• fuels for use on fuel cells , such as methanol , methane or propane , depending on operational conditions and on the fuel cells ' technology and components .
• this gas is introduced into the anode , where it reacts electrochemically by means of a catalyst forming ions H + (protons) and electrons .
• H + protons
• electrons move from the anode onto the cathode through an outer electrical circuit .
• the protons when surrounded by water molecules , move through the electrolyte onto the cathode side where they recombine with electrons , from the outer circuit , and oxygen molecules , from the air, also by means of a catalyst , forming water molecules .
• Electrical Work is produced by the movement of the electrons through the outer circuit if a load is applied .
• a hydrogen-fuel cell stack comprises a stack of several fuel cells , which usually means the component which makes the separation between each cell is a bipolar plate which, besides doing the electricity collection, also has hydrogen diffusion channels on one side and oxygen, or air, diffusion channels on the other .
• These channels can have a number of configurations possible : with parallel channels on one side relative to the other, with perpendicular channels on one side relative to the other, or with a combination of these two designs .
• these channels have a width between lmm and 2mm, and their depth can vary between 0 , 2mm and 3mm, and they may have different dimensions throughout the gases ' pathways .
• the thickness of the plates depends on the channels ' depths on both faces , of the sealing applied and of the plate ' s material .
• bipolar plates are usually rectangular envisaging the square , as this last shape allows for the optimization of the electrode ' s usable area, maximizing electricity collection . They can also present other useful shapes as , among others , hexagonal , octagonal , circular, etc .
• Bipolar plates must be made from a material which allows for the stressful operation conditions ; this material must be good electrical conductor, chemically inert , hydrogen impermeable and mechanically sound .
• the materials normally used as bipolar plates are : graphite , or graphite compounds, titanium, titanium oxide , niobium, stainless steel and other metals with the electrodepositing of noble metals (usually gold) .
• the sealings usually used in hydrogen-fuel cells are from an elastic nature (rubber, silicon, PTFE , resins and glues) , they must have fair thermal and chemical stability and they must be impermeable to hydrogen .
• the bipolar plate has in its core (between the hydrogen channels and the air channels , at its surface) special channels for the circulation of a cooling fluid, normally water or air, which makes easier to manufacture these plates as the junction of two separate plates , one with the hydrogen channels and the cooling channels and other with the oxidant channels and the cooling channels ;
• a cooling fluid normally water or air
• an outer system is needed for the water to cool (radiator) , and the water travels between the radiator and the plate ;
• air is used as a cooling fluid, it travels through the plate removing its heat and it is usually vented outside the device .
• the heart of the fuel cell is the Membrane- Electrode Assemblies - MEAs ; the way these assemblies are made have a decisive influence on any fuel cell ' s performance .
• the assembly of the electrodes with the membrane depends on the initial deposition of the catalyst : if the catalyst is applied directly upon the membrane, the electrodes are usually applied upon the membrane on the manufacturing stage , so we deal with a pre-arranged set of electrodes - catalyst - membrane ; if the catalyst is applied on the electrodes , the MEA is usually done at the final stage of the cell assembly, and they can be done by merely compressing the components together between the bipolar plates .
• Almost all kinds of MEAs include the proton exchange membrane with a platinum film deposited on both sides and two hydrophobic electrodes , usually carbon paper or carbon cloth, on each side of the membrane .
• the maj or technology issues yet to be solved relate to : 1) how to manage the water formation and disposal ; 2 ) how to stack the cells as to ensure all receive the proper amounts of reagents , to ensure the temperature is balanced and to ensure each membrane has a stable and adequate water content .
• One other requisite for a high performance fuel cell is the use of a membrane which must have a high ionic conductibility, an elevated lifespan and fair mechanic stability.
• U. S . Patent N° . 6.770.394 concerns an electrochemical fuel cell containing a first and a second monolithic electrically conducting flow field-bipolar plate assemblies arranged essentially parallel to each other such that an inside surface of the first bipolar separator plate is facing an inside surface of the second bipolar separator plate, wherein the bipolar separator plates are electrically and mechanically connected by intervening layers that are directly bonded to each other .
• the fuel cells can be stacked between endplates and supplied with hydrogen and oxygen to generate electric power .
• An air cooled condenser for use with a fuel cell stack is composed of a porous foam condensing element and a porous foam cooling element . The condenser can be placed by a fuel cell stack for cooling purposes .
• US Patent N° . 6 , 677 , 071 concerns an invention related to a bipolar plate for a fuel cell , the bipolar plate comprising a central area and a surrounding area, wherein the central area has a first side surface and a second side surface opposed to the first side surface , the central area is in a form of continuous corrugation which defines a plurality of grooves that are substantially parallel with and complementary to each other on each of the first side surface and the second side surface .
• the thickness of the bipolar plate of this invention can be very thin so as to decrease the dimension and weight of the fuel cell .
• the grooves are connected to elongated holes in the surrounding area by channels which are formed in a longitudinal direction on a first side and in a direction transverse to a longitudinal direction on a second side .
• US Patent N° . 6 , 786 , 937 concerns a fuel cell stack including a stack of flow plates , a first gasket that is compatible with a coolant and a second gasket that is incompatible with the coolant .
• the stack of flow plates includes openings to form a coolant passageway that communicates the coolant and a reactant manifold passageway.
• the second gasket forms a seal around the reactant manifold passageway between an adj acent pair of the plates .
• the first gasket forms a seal around the coolant manifold passageway between the adj acent pair of plates .
• At least one region of a particular plate may be associated with a reactant flow, and this plate may include internal passageways that extend between manifold passageways to communicate a coolant .
• US Patent N° . 6 , 699 , 613 concerns a fuel cell comprising : a membrane electrode assembly having a solid polymer electrolyte membrane , an anode side diffusion electrode (an anode electrode , and a second diffusion layer) disposed at one side of the solid polymer electrolyte membrane , and a cathode side diffusion electrode (a cathode electrode , and a first diffusion layer) disposed at the other side of the solid polymer electrolyte membrane ; a pair of separators which hold the membrane electrode assembly; a proj ecting portion which extends from the solid polymer electrolyte membrane and which proj ects from the peripheries of the anode side diffusion electrode and the cathode side diffusion electrode ; and a seal , provided on the separators , which was liquid sealant at the time of application . The seal makes contact with the proj ecting portion while the membrane electrode assembly is disposed between the separators .
• US Patent N° . 6 , 689 , 500 concerns a fuel cell system including a first reactant intake manifold, a first reactant output manifold, a second reactant intake manifold, a second reactant output manifold, a cooling gas intake manifold, a cooling gas output manifold, a liquid intake manifold, fuel cells and a cooling elements distributed among the fuel cells .
• Each cooling element defines a coolant passage .
• a cooling gas flows from the cooling gas intake manifold into the cooling gas output manifold through the coolant passage .
• Each cooling element also includes a water inj ection path . During operation water from the liquid intake manifold is inj ected into the coolant passage to mix with the cooling gas passing there through .
• US Patent N° . 6 , 817 , 097 concerns a heat pipe assembly including a base plate and a corrugated lid j oined to the base plate to form a plurality of tubes between the base plate and the corrugated lid .
• Each of the plurality of tubes forms an envelope of a respective heat pipe within the heat pipe assembly.
• the heat pipe assembly may be included in a fuel cell stack. As one may infer from what is going to be presented, the following invention has many and substantial differences to the actual state of the art .
• - 2 represents a view from the bottom of a bipolar diffusion plate , with the air flowfields clearly visible ;
• - 4 represents a view of a fuel cell stack by the integration, or stacking, of five individual fuel cells .
• Figure 1 represents the hydrogen flowfield side of a bipolar diffusion plate 1 , with 17mm x 42mm, where highlighted channels 3 are for hydrogen diffusion.
• references 2 and 4 represent the hydrogen' s circuit connections to the following Individual Cell . This portion' s depth/ and of the surrounding area, is 1 mm, as to facilitate the flow between the plates .
• the channel 3 from the hydrogen circuit whose depth is less than lmm ( 0 , 6mm at the Figure) , and its width is lmm, for an optimized proportion between contact area and the active area .
• Figure 3 presents all the components of an Individual Cell :
• Figure 4 presents a hydrogen- fuel cell with five integrated Individual Cells , where the following specifications are to be noticed :
• the present fuel cell is characterized by : Gas diffusion plate 1 , with the hydrogen side making, together with the Membrane electrode assembly 8 , a tight chamber who allows the operation under a dead-ended configuration;
• the air supply system performs simultaneously three functions all crucial to the stacks fine performance :
• Oxygen supply oxygen being a primary reagent of the electrochemical reaction
• the system being presented allows for a permanent humidification of the membranes 8 , dispensing with the usual previous humidification of the hydrogen, all because of the pronounced osmosis effect on said membranes .
• An excess water formation can sometimes happen, easily manageable by a periodic purge to the outside of the stack .
• the drawing of the hydrogen diffusion channels 3 follows a principle of maximization of the reactional area relative to the plates ' total area ( 65%) , maximization accomplished by the perpendicular communication between channels (because the supply is dead-ended, the hydrogen flow within the plate is made into all directions) and by determining the distance between channels at 1 millimetre . This maximization was accomplished without interfering with the current collection .
• the depth of the hydrogen channels which seems to provide the best results is between 0 , 5 and 1 , 5 millimetres , perfectly in tune with the cells ' operation pressures . However, it is possible to draw hydrogen distribution channels with other depths .
• the width of plate 1 which corresponds to the length 'of the air diffusion channel 5 , is determined depending on the power and of the static pressure of the blower used . The goal is to limit the pressure fall through the channel 5 to values under the blower' s static pressure .
• bipolar diffusion plates 1 are used where on one side hydrogen supply channels 3 are drawn and on the other side axial air channels 5 are drawn .
• the polymeric membrane MEA 8 forms a j oined set with the bipolar plate on the hydrogen side by the use of adhesive materials 9 , while the materials used on the air side are non-adhesive .
• This concept allows for the stack' s easy disassembly for the eventual substitution of any cell without damaging the rest of the stack .
• the hydrogen supply is made through a single circuit traversing all cells , which means the fuel reaches one cell after travelling through all previous cells (accumulating some moisture from cell to cell , improving the fuel ' s ability to reach the reactional points) .
• the main goal changes from the hydrogen' s carriage at the surface of the membrane to its reposition as it is being spent , goal easily obtained by a homogeneous hydrogen distribution throughout all plates and through the entire surface of each plate .
• the hydrogen supply circuit When the hydrogen supply circuit has two extremities , as to make a purge of the water excess , the hydrogen supply can be made alternately between the two ends ; this rotation will allow a greater fuel homogenization and humidification, overcoming the traditional poorer performance of the cells closer to the fuel entry.
• this system has a combined strategy of periodic purges of the hydrogen supply circuit and of microscopic cuts of the connection to the load as a way to ensure the stabilization of the voltage over time .
• These purges can be made simply by drastically reducing the pressure on one pf the supply circuit ' s ends , leading to the expansion, on the microscopic level , of the water condensed on the membranes ' surface .
• the hydrogen supply on traditional stacks is fixed, meaning it always enters through the same orifice and always exits through another .
• the entry and exit points change periodically as to homogenise the moisture within the hydrogen chamber .
• the temperature reached by the units being tested with the ventilation system being described does not exceed 40 ° Celsius , meaning its operation does not involve any potential risks or setbacks (many hydrogen stacks reach much higher temperatures , around 80- 90 ° C, involving a more delicate handling) .
• the invention being described allows superior performances than the ones obtained with other hydrogen- cell stacks , or than the ones obtained with conventional systems such as battery packs , on the power range between 5 and 500 Watt , making the system particularly fit for its integration into portable or mobile electrical power sources .
• each cell includes (Fig . 3 ) : - One plate 1 made from copper, graphite or other electrically conductive material , with the gas diffusion channels drawn on its surface ;
• - One other Torey carbon paper, or carbon cloth, 10 ;
• - One plate 1 made from metal or any bonding polymer that is an easy gas diffuser electrically conductive material , made in such a way that one of its sides has a hydrogen diffusion flowfield and the other has an air diffusion flowfield; the plate from Fig . 1 shows quite visibly these hydrogen diffusion channels 3 , while Fig . 2 shows the same plates opposite side with the air diffusion channels 5.
• an adhesive sealing piece 9 On the plate ' s hydrogen side , an adhesive sealing piece 9 , easily commercially available , will be affixed; this sealing constitutes a frame , or window, for the remaining central components of the Individual Cell (Fig .
• the carbon paper, 10 at Fig . 3 used can also be easily acquired at any specialist manufacturer, being cut with a simple cutting tool to the framing shape defined by the sealing piece .
• the polymeric cationic exchange membrane (8 at Fig . 3 ) is also cut in the shape defined by the sealing piece .
• a non-adhesive piece is applied to the outer side of the sealing, to prevent the previous adhesive sealing to touch the air side of the following plate .
• Figure 4 shows a hydrogen-cell stack composed by 5 ICs , each with 3 , 8 square centimetres of active area, allowing an approximate 1OW output , of which between 0 , 4 and IW will be to feed the auxiliary systems .
• This stack is composed by two structural plates 6 , two golden copper electricity collectors 7 and by two electrically insulated screws .
• Structural plates 6 show two holes 13 at which the driving screws pass through, one other central hole with a M5 inward spiral and a 2 millimetre hole for the hydrogen entry .
• There is also a special channel on these plates with a width of two millimetres and a depth of three millimetres linking the previous hole to the central M5 hole , so the hydrogen supply is made through the central hole .
• the system being described can obtain maximized results by the use of microscopic interruptions (well below one second) of the connection to the load as to stabilize the voltage ; this is particularly useful when the system is not directly connected to the final application but instead is part of an hybrid system, which can act as a single system where the battery supplies enough power to hold the final applications ' consumption peaks while the fuel cell supplies the energy which will allow for an enlarged autonomy of the system.

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• General Chemical & Material Sciences (AREA)
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• 2004
  • 2004-12-21 PT PT103221A patent/PT103221B/pt active IP Right Grant
• 2005
  • 2005-12-21 EP EP05819211A patent/EP2097942A2/de not_active Withdrawn
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