DE102005004048B4 - Spiral Micro Fuel Cell - Google Patents

Abstract

A spiral micro fuel cell for the conversion of chemical to electrical energy via a chemical reaction between two fluid streams, comprising
a) a gas-impermeable electrolyte membrane,
b) one anode (4) and one cathode surface (5) each, arranged or applied on each side of the electrolyte membrane and
c) two separate fluid guides (6, 7), wherein a fluid guide (6) on one side of the electrolyte membrane with contact to the anode surface (4) and the other fluid guide (7) on the other side of the electrolyte membrane with contact to the cathode surface (5) is arranged, these are each assigned to one of the two fluid streams and both ends in each case in at least one terminal (8, 9, 11, 12),
characterized in that
e) the electrolyte membrane consists of a rectangular membrane foil element (3) folded in half around a fold line (2) and then rolled up around the fold line.

Description

The The invention relates to a spiral micro fuel cell for the conversion from chemical to electrical energy via a chemical reaction between two fluid streams according to the first Claim.

fuel cells are galvanic systems in which a chemical bound energy is converted into an electrical energy. They essentially exist from a layer composite of an anode, a solid electrolyte and a cathode, wherein the electrolyte is an electrical insulator between the cathode and the anode. Serve anode and cathode not just as the electrical poles of a fuel cell, but also as a catalyst for the at these occurring chemical reactions.

at Most fuel cell types become hydrogen at the anode and to the cathode oxygen (with exception: methanol fuel cell, at the methanol and air form the reactants). It happens to an anode-side release of electrons with splitting of the hydrogen molecule to hydrogen atoms. The resulting hydrogen ions become from the anode over transfer the electrolyte to the cathode and oxidize there with the addition of the cathode-side oxygen to water. The therefor required electrons emitted at the anode, however, can no over the electrolyte (electrical insulator) passed directly to the cathode but over the detour of a connected to the cathode and anode electrical Consumer, i. as usable electric power. In the case of the aforementioned oxygen-hydrogen fuel cells A constant between anode and cathode of a cell Voltage of just over 1V For generating larger voltage values or Electricity values are fuel cells like other sources of power and voltage in series or parallel switchable.

you differs depending on the material pairing of the layer composite between various types of fuel cells (e.g., alkaline fuel cell (Potassium hydroxide solution as electrolyte), polymer electrolyte membrane fuel cell, phosphoric acid Fuel cell (phosphoric acid as electrolyte) or molten carbonate fuel cell (molten salt from alkali carbonates as electrolyte), etc.).

Spiral micro fuel cells The type mentioned above are characterized by a rolled up Layer composite of the aforementioned type. In this are two fluidically separated fluid guides with contact to the anode (for hydrogen) or to the cathode (for Oxygen). Due to a pronounced flexibility and thus a windability of polymer films in general is the Type of spiral micro fuel cells, in particular for polymer electrolyte membrane fuel cells (PEM) fuel cells.

In the DE 197 39 019 C2 describes a wound around an inner cylindrical sleeve PEM fuel cell with an outer cylindrical shell, wherein the flow takes place in a spiral between feed and discharge lines in the region of the two sleeves.

Also in the DE 1 805 022 A discloses a spirally wound fuel cell, wherein the anode and cathode axially offset from each other in the winding project into an electrolyte. The respective anode and cathode surfaces which are not located in the electrolyte penetrate separately from the respective other electrode surface into an individual flow-through chamber for hydrogen and oxygen.

Furthermore, in the DE 25 34 725 A discloses a spirally wound fuel cell in which the anode and cathode surfaces each comprise a channel fraction of a plurality of groove-shaped channels arranged parallel to each other, wherein the first channel fractions are oriented tangentially and the second is oriented axially to the fuel cell, ie orthogonal to the first channel fraction.

Of the particular advantage of this latter type is the typical type huge specific transfer surfaces of the fluid channels (Fluid guides) to anode surface to cathode surface, i.e. in the efficient high specific reaction area with a compact design.

The mentioned embodiments However, they have a relatively high number of components, which a relatively complex production entails you want one ensure absolute fluidic separation of oxygen and hydrogen. In addition, stand in the cells according to the state the technique does not use the entire electrode area of the anode and cathode as Reaktonsfläche to disposal, which inevitably results in a larger size for a required performance pulls with it.

task The invention therefore, a spiral micro fuel cell of the above to suggest the type mentioned, the concept of a production with filigree dimensions and with high reliability very simplified and at the same time an increased development the electrode surfaces for the Ensures output fluids (containing hydrogen or oxygen).

To solve the problem, a spiral micro fuel cell with the features of claim 1 is proposed. Advantageous embodiments of Spiral micro fuel cell are given in the subclaims.

The The invention relates to a spiral micro fuel cell such as the aforementioned wound fuel cell, preferably one of the type PEM fuel cell (because flexible polymer membrane) for the conversion of chemical into electrical energy over a chemical reaction between two fluid streams (containing hydrogen or oxygen) with spiral or helical Fluid management. With a spiral or helical Fluid guide is meant that the fluid flows in the spiral micro fuel cell from the inside out or reversed be guided through the entire spiral area. With it all fluid guides within the equivalent range, which does not support the spiral area laterally (i.e., in the axial direction) leave. Thus, the invention of pure or partial borders axially flowed through Spiral micro fuel cells, i. with a fluid flow in parallel to the spiral heat exchanger axis from. Consequently, the invention comprises at least one connection each per fluid fraction on the outer surface of the Spiral micro fuel cell and one port per fluid fraction the central axis of the spiral micro fuel cell, i. preferably in the middle region of the preferably round end faces of the spiral micro fuel cell.

The Spiral micro fuel cell comprises a polymeric gas impermeable electrolyte membrane. On this are areal arranged on one side each have an anode and a cathode surface (e.g., laid-on or laid-on) or applied (e.g., glued or coated). The two fluid-tightly separated fluid guides for the Rekationsfluide, preferably a hydrogen and an oxygen-containing Gas, are called structures in the membrane or the anode surface and cathode area introduced, wherein the electrode contact of the fluid guides preferably extends to its entire structure, but each of the fluid guide only Contact with an electrode (cathode or anode) has. Preferably are two fluid guides as inserted into the electrodes Structures provided, one the anode surface (for hydrogen) and the other the cathode surface (for oxygen) penetrates. The inserted structures preferably comprise a plurality of parallel interconnected channels, which one side of one of the anode-side or cathode-side fluid fractions form associated channel fraction and both sides in a port enter or exit. preferably, flow while the channels on both sides in each case a groove-shaped Channel, e.g. a groove-shaped Well, as part of a connection. Alternatively, the Structures on the laminate as distributed over the entire surface Spacers designed to be wrapped by these in the State a spiral Gap results.

The spirally wound edge regions of the membrane film (end faces) are, except the openings for the Connections, designed fluid-tight sealing or sealing covered.

Essential is that the electrolyte membrane with the applied on both sides Electrode surfaces (cathode and anode) from a folded and subsequently rolled around the fold line membrane sheet element consists. It makes sense, the film element to rectangular shape and half to fold a fold line, i. the halves are preferably in unwrapped state with each whole area on each other. Divided the fold line the film element so in two equal halves, where they are parallel to two of the four marginal lines of the film element runs. Alternatively, the folding also offset have an off-center position, so that the both faces with their respective total area in the rolled state to each other. Thus, the spiral micro fuel cell has preferably a cylindrical shape with two end faces and a circumferential surface area.

at a convolution followed by Winding of the aforementioned layer composite are at an extension the electrode layers over the entire membrane foil surface automatically anode surface on anode surface and cathode surface on cathode surface. Here are the aforementioned spacers in particular advantageous manner for the formation of fluid guides.

alternative the membrane film element has two surface sides, wherein the one Surface side up one half and the other opposite surface side on the other half are structured with incorporated depressions. Both halves of the Membrane foil element are e.g. only structured on one side while the each opposite surface side per half each smooth, i. is unstructured.

Preferably are the fluid guides spirally between the fold and the outer surface of the coiled electrolyte membrane oriented and extend over the entire anode and cathode surface. The fluid guides preferably comprise a plurality of non-parallel aligned to the folding grooved Channels, which per fluid fractions near the fold line and outdoors each in a connecting line, preferably a groove-shaped recess as part of a connection.

Likewise, each of the two surface sides can be coated on only one half with an electrode and be uncoated on the other half, wherein preferably both halves are coated only on one side. In this form, the pre Fluid guides mentioned as incorporated (eg embossed or mechanically incorporated) structures on both the electrode surface and on the membrane film present.

All electrode surfaces (Anode and cathode) are also in a structured state electrically continuously. Likewise, the membrane film is also incorporated with structures fluid-tight, i. without breakthroughs.

It is within the scope of the invention, when the wound membrane film rolled up by one or more other fuel cell components is, which preferably have a cylindrical shape and, for example as connections for two or more fluid fractions serve.

The fluid guides each extend from the folding line to the opposite Folding line lying and parallel to these marginal lines the membrane sheet element. Preferably, the two lateral remain Edge regions which are not arranged parallel to the fold line are, at least outside the area of the fold line (this area is namely the Connection to the spiral micro fuel cell can be taken over its end faces) unstructured. The structures extend over the aforementioned lateral Edge areas are the faces of the rolled sheet segment, i. the open channel flanks against each other by suitable means, for example via a molten or cover glued lid fluid-tight.

Essential is that in the rolled film element in the edge areas possibly also over Spacer fluid-tight plan lie on each other. The fluid-tight Compound is on the one hand with the known bonding or welding methods (e.g. Diffusion welding) also alone over a surface pressure, feasible for example via a winding of a tensioned under train membrane sheet element.

It lends itself to the aforementioned two covers not only as a sealing axial conclusion with fluid connection of a wound GE fuel cell use, but also electrical connection for the anode and cathode, taking the anode surface one and the cathode surface on the other end face axially protrude from the rolled membrane sheet member.

The Invention is primarily based based on the idea of drastically reducing fuel cell components on the one hand and the number and the required accuracy of the manufacturing steps on the other. But a reduction of the components in turn causes a reduction of joint surfaces, what advantageously usable in the sense of a transfer efficiency increase is. Furthermore open the concept of the invention in principle filigree structures and thus a very high specific energy transfer especially for small sizes.

embodiments The spiral micro fuel cell will be explained below with reference to figures, wherein illustrated features exemplary of the invention in its entirety Width disclosed and are not limited to the illustrated embodiments. Show it

1a and b show the construction of two exemplary embodiments of the invention in a lateral sectional view,

2a and b a membrane sheet member of the spiral micro fuel cell according to FIG 1a before folding and curling,

3a and b a membrane sheet member of the spiral micro fuel cell according to FIG 1b before folding and curling up as well

4 a further embodiment comprising a breakthrough in the membrane sheet element.

The basic structure of a spiral micro fuel cell according to the invention is shown as a side sectional view in 1a and b reproduced. Both embodiments include a guide member 1 comprising a rectangular half-way around a fold line 2 folded and then rolled around the fold line membrane sheet element 3 each with an anode surface 4 (for hydrogen) and a cathode surface 5 (for oxygen) as electrode layers. In the electrode layers are the fluid guides 6 (for hydrogen) and 7 (for oxygen) incorporated in the form of groove-shaped depressions. The fold line extends over the membrane foil element 3 and is regarding 1a and b aligned orthogonal to the cutting plane. Furthermore, both embodiments each have an outer connection for each of the two fluid fractions 8th (for hydrogen) and 9 (for oxygen) on the outer surface of the guide member 1 and one inner connection each 11 (for hydrogen) and 12 (for oxygen) at or near the fold line 2 on.

While 1a an example embodiment without an outer sheath 13 shows and the connections are placed directly on the wound layer composite shows 1b a second embodiment with a sheath 13 , which with the laminate two cavities 14 (for hydrogen) and 15 (for oxygen) forms, in which the fluid channels 6 and 7 as well as the external connections to end up. Also represented 1a an embodiment with both sides over the entire surface of the membrane film 3 extending electrode surfaces (anode surface 4 and cathode surface 5 ), while 1b an embodiment in which the anode surface 4 on the membrane half and the cathode surface 5 extends on the opposite side of the other membrane sheet half.

The aforementioned half folding does not necessarily mean a division into two halves of exactly equal size. Rather, the size and extent of the two halves depends on the desired position of the terminals 8th and 9 in the area of the outline, but also in the design in the area of the folding line 2 It should be noted in principle that in the case of a helical winding of a plurality of halves lying one above the other, they are rolled up at different speeds.

The for the embodiments according to 1a and b required design of the structures on the membrane sheet element 3 is in 2a and b or 3a and b reproduced. In each case, the respectively designated with a) figure respectively gives the front view and the figure designated b) in each case the rear view of the same membrane film element again. Centered on the membrane foil elements 3 are the fold lines 2 ,

In the first embodiment ( 1a and 2a and b) include the connections 8th . 9 . 11 and 12 each a groove-shaped depression 14 to 17 each parallel to the fold line 2 , They serve as inflows and outlets of the likewise groove-shaped in the membrane film element and / or in the electrode layers incorporated fluid guides 6 and 7 and each lead to an edge of the membrane film element. By way of example, the fluid guides are straight grooves oriented orthogonally to the fold line with webs arranged therebetween 18 shown. It is recommended in particular in laterally arranged connections in general but, the two fluid guides 6 and 7 to optimize flow and thermodynamically coordinated (ie, in principle, a deviation from the exactly straight and orthogonal to the folding line aligned groove-shaped fluid guides 6 and 7 ).

For the introduction of in 2a and b shown, for example depressions and structures in a membrane sheet element is particularly suitable for an etching or mechanical method, in particular a micro-milling process.

Even if the electrode surfaces of the aforementioned embodiment on the membrane film on both sides of the fold line 2 In principle, and in this embodiment in particular, an extension of the incorporated fluid guides and other groove-shaped depressions for each of the two sides only on one half of the membrane film, although not necessary, is quite sufficient. Basically, in all the illustrated embodiments, an extension of the incorporated structures such as the aforementioned fluid guides and groove-shaped depressions on both sides of the membrane film on both halves is conceivable, and indeed incorporated in membrane film and / or in the electrode surfaces. It should be noted, however, that in principle a diffusion of hydrogen ions takes place through the regions of the membrane film which is not covered by an electrode surface. In the second embodiment ( 1b such as 3a and b) covers the anode surface for this reason 4 and cathode surface 5 the membrane sheet element 3 only half of each side.

The anode surface 4 and cathode surface 5 are not divided by the structures and fluid guides into a plurality of electrically isolated islands or areas.

In contrast to the embodiment in 1a has that according to 1b not just a tubular outer shell 13 forming constructive external cavities 19 (for hydrogen) and 20 (for oxygen) between guide component 1 and sheath 13 (From electrically non-conductive or in the case of a pole for the fuel cell of partially conductive material), but also two other lying in nen cavities 21 (for hydrogen) and 22 (for oxygen) in the region of the folding line 2 on. All four cavities serve as orifices or junctions for the individual fluid guides (groove-shaped recesses 6 respectively. 7 ) and are part of the connections 11 and 12 in the area of the folding line 2 or the connections 8th and 9 in the area of the casing (outer surface). As in 3a and b, no structures introduced as depressions into the membrane film element are required as part of the connections for this exemplary embodiment, which advantageously reduces the manufacturing outlay when introducing the structuring into the membrane film element. In particular, only the groove-shaped recesses (fluid guides 6 and 7 etc.), which can also be made by a simple machining, such as bumping or grinding.

It is advisable, depending on the end faces of the rolled-up membrane sheet element to seat a preferably cylindrical cover. Even if the areas of the membrane film element in the rolled-up state lie sealingly on one another, these serve. Cover at least as a carrier for the aforementioned Anschlüs se.

Furthermore, it lends itself to the footbridges 18 with a configurable advantage of greater fluid capacity or larger available electrode surfaces in the fluid guides on the one hand and better rollability of the membrane sheet element on the other hand by a poorer management of the fluids is reduced in the fluid guides. The elevations can also be separated by the fluid guides 6 and 7 Create crossing grooves parallel to the fold line, wherein the grooves must be sealed by the aforementioned cover at the end faces to the outside.

4 shows a further embodiment in which the around the folding line 2 folded membrane foil element around a profile strip 23 is wound with cylindrical outer contour and a divided inner volume. The two inner volume parts serve as connections 11 (for hydrogen) and 12 (for oxygen) at the folding line for the two fluid fractions and correspond via a respective longitudinal slot 24 . 25 with the fluid guides 6 (for hydrogen) and 7 (for oxygen). Another special feature is the fluid feedthrough 26 for structurally conditioned fluidic bridging of the membrane film element. It lends itself to the profile strip 23 as two mutually electrically insulated strips with semicircular cross-section to make and as an additional electrode surface and as a connection for electrical loads to the anode surface 6 and the cathode surface 7 for the microspiral fuel cell.

Likewise, the sheath is 13 segmentally electrically conductive for electrical connection of electrical loads to the electrode surfaces (anode surface and cathode surface) of the fuel cell zoomable.

The aforementioned assignments of certain components to hydrogen Hydrogen-containing fluids also include fluid mixtures such as Gases or gas mixtures and methanol (with and without water in the case a methanol fuel cell) as Eduktionsmittel. Analogously include the aforementioned assignments of certain components to oxygen as well as oxygen-containing gases, fluid and gas mixtures and fluids such as. Atmospheric air.

The aforementioned applied electrode surfaces (on the membrane film element applied anode surface and cathode surface) can both separate textured wrapped with the membrane sheet element or unstructured (for spacers or structured membrane foil) conductive Be films, as well as before the winding process with the membrane film element be applied metal coatings. As a metal coating they can both in a PVD (e.g., sputtered, evaporated, etc.) or CVD coating process be applied, wherein the fluid guides either before coating be introduced into the membrane film or structuring only in the coated state. The anode surface and cathode area can also dense or to increase the specific electrode surface made porous be, with an open porosity partially or completely as a fluid guide serves in the aforementioned sense. Furthermore, the edge regions of the membrane film element and the electrode surface, in particular the fluid guides To make fluid-tight or gas-tight or seal.

It is due to the particular advantages of an anode surface and a cathode surface, the each separately in the wound layer composite via one of the frontal side Be edge regions of the membrane sheet element addition, the each other electrode surface ends just before the edge area in the layer composite, referenced. frontal conductive Lid can be designed so that they to the respective protruding electrode surface an electric Having contact and heranziehbar for contacting the fuel cell are.

1

guiding member

2

fold line

3

Membrane sheet member

4

anode surface

5

cathode area

6

Fluid guide (hydrogen)

7

Fluid guide (oxygen)

8th

outer connection (Hydrogen)

9

outer connection (Oxygen)

11

Connection to the Folding line (hydrogen)

12

Connection to the Folding line (oxygen)

13

jacket

14-17

Grooved depressions for fluid guides

18

web

19-22

cavity

23

Molding

24 25

longitudinal slot

26

Fluid passage

Claims (9)

A spiral micro fuel cell for the conversion of chemical energy into electrical energy via a chemical reaction between two fluid streams, comprising a) a gas-impermeable electrolyte membrane, b) one anode each ( 4 ) and a cathode surface ( 5 ), arranged or applied on each side of the electrolyte membrane and c) two separate fluid guides ( 6 . 7 ), wherein a fluid guide ( 6 ) on one side of the electrolyte membrane with contact to the anode surface ( 4 ) and the other fluid guide ( 7 ) on the other side of the electrolyte membrane with contact to the cathode surface ( 5 ) is arranged, these are each assigned to one of the two fluid streams and on both sides in each case in at least one connection ( 8th . 9 . 11 . 12 ), characterized in that e) the electrolyte membrane consists of a rectangular half-way around a fold line ( 2 ) and then rolled around the fold line membrane sheet element ( 3 ) consists. Spiral micro fuel cell according to claim 1, characterized in that the fluid guides spiral between the fold line ( 2 ) and the outer surface of the coiled membrane sheet member are oriented and extend over the entire anode and cathode surfaces. Spiral micro fuel cell according to claim 1 or 2, characterized in that the fluid guides ( 6 . 7 ) comprise a plurality of groove-shaped channels not aligned parallel to the fold. Spiral micro fuel cell according to claim 3, characterized in that the channels per side of the membrane film element ( 3 ) form a channel fraction, which are each associated with one of the two fluid fractions and on both sides in each case in a connection ( 8th . 9 . 11 . 12 ) end up. Spiral micro fuel cell according to claim 3 or 4, characterized in that the fluid guides ( 6 . 7 ) have on both sides of the membrane sheet element in the region of the fold line a groove-shaped depression oriented parallel to the fold line as part of a respective connection and as connecting line between the ends of the channels per channel fraction. Spiral micro fuel cell according to one of the preceding claims, characterized in that the fluid guides ( 6 . 7 ) in the membrane film element ( 3 ) and / or the anode and cathode surface ( 4 . 5 ) are incorporated. Spiral micro fuel cell according to one of the preceding claims, characterized in that around the outer surface of the rolled-up membrane foil element a tubular sheath ( 13 ), wherein in this two axially aligned grooves are provided as part of a respective connection and as a connecting line between the ends of the channels per channel fraction. Spiral micro fuel cell according to one of the aforementioned Claims, characterized in that on the two end faces of the rolled up membrane sheet element depending on a lid sealingly placed is. Spiral micro fuel cell according to claim 8, characterized characterized in that the two covers electrically isolated from each other connections for the Anode and cathode surfaces form, wherein the anode surfaces at one and the cathode surfaces on the other end face survive the rolled membrane film element.