Title of Invention	AN ELECTROCHEMICAL COMPRESSOR SYSTEM AND FUEL CELL SYSTEM.
Abstract	The invention deals with! art electrochemical system for compressing gases and/or forproducing gases by elecrolsis. consisong of an electrochemical-compressor"stack; (1) having layering of Several electrochemical, which are separated fram one another in each case by bipalor plates (5; 3") wherein the bipalor plats have opening. for media supply and media dischange (Ja. 5b) fur the electrochemical cells and the electrochemical cell stack tan be pioced under mechanical compresive stain in direction (6) of the layering. The bead arrangement (7; 7") are resident-and are provided at least in some regions to seal the openings (4, 5a. 5b) and/or an electrochemically active region (10) of the electrochemical cell.

Title of Invention

AN ELECTROCHEMICAL COMPRESSOR SYSTEM AND FUEL CELL SYSTEM.

Abstract

The invention deals with! art electrochemical system for compressing gases and/or forproducing gases by elecrolsis. consisong of an electrochemical-compressor"stack; (1) having layering of Several electrochemical, which are separated fram one another in each case by bipalor plates (5; 3") wherein the bipalor plats have opening. for media supply and media dischange (Ja. 5b) fur the electrochemical cells and the electrochemical cell stack tan be pioced under mechanical compresive stain in direction (6) of the layering. The bead arrangement (7; 7") are resident-and are provided at least in some regions to seal the openings (4, 5a. 5b) and/or an electrochemically active region (10) of the electrochemical cell.

Full Text	Electrochemical system The present invention relates to an electrochemical system, such as for example a fuel cell system or an 5 electrochemical compressor system. Electrochemical compressor systems may be, for exam- ple eleotrolysers, which by applying a potential, in addition to producing, for example water and oxygen 10 from water, compress these gases at the same time un- der high pressure. In addition, electrochemical compressor systems, such as for example electrochemical hydrogen compressors, 15 are also known, to which gaseous molecular hydrogen is supplied and the latter is compressed electro- chemically by applying a potential. This electro- chemical compression is available particularly for small quantities of hydrogen to be compressed, since WO 2004/036677 PCT/EP2003/011347 2 mechanical compression of hydrogen would be consid- erably more expensive here. Electrochemical systems are known, in which an elsc- 5 trochemical cell stack is constructed with layering of several electrochemical cells, which are separated from one another in each case by bipolar plates. The bipolar plates thus have several tasks: 10 - electrical contacting of the electrodes of the individual electrochemical cells and conveying the current to the adjacent cell series connection of the cells, - supplying the cells with reactants, such as for 15 example water or gases and, for example removal of the reaction gas produced via an appropriate dis- tributor structure, - conveying the heat being produced during genera- tion in the electrochemical cell, and 20 - sealing off of the various media ducts or cool- ing ducts with respect to one another and externally. The bipolar plates have openings for cooling or media supply and media discharge for media supply and media 25 discharge from the bipolar plates to the actual elec- trochemical cells (these are for example MEA (Mem- brane Electron Assembly) having a gas diffusion layer, for example made from a metal mat, orientated in each case towards the bipolar plates). 30 Difficulties regularly result here particularly with regard to the gas diffusion layer. It has been con- ventional hitherto to design the seal between the bi- polar plates or -between bipolar plates and the elec- 35 trochemical cell in that an elastomer seal is placed, for example in a groove of the bipolar plate. By ex- WO 2004/036677 PCT/EP2003/011347 3 erting compressive strain (for example by means of tension bands) on the electrochemical cell stack, pressing of the seal then takes place, as a result of which a sealing effect should be achieved for the 5 openings - It is now a problem for the inserted gas diffusion layer that it may be designed as a fibre mat (with metal fibres) or metal mesh. Fibre mats which are 10 conventional in industry have a theoretical thickness of, for example l mm, but the manufacturing tolerance is + 100 pm. The metal fibres which construct the mat are themselves only slightly resilient. In addition, it is also not recommended to compensate production 15 tolerances of the fibre mat by compressing the mat, since the gas permeability of the mat layer is thus severely diminished and hence operation of the elec- trochemical cell is restricted. On the other hand however, it is necessary to exert a minimum pressure 20 on the entire gas diffusion layer by the bipolar plate, so that there is an adequate passage of cur- rent through the gas diffusion layer. It can thus be summarised that for the current elastomer seals, ei- ther a non-perfect seal or non-optimum operation of 25 the electrochemical cell was thus to be accepted. In addition, particularly for electrochemical cells op- erated using molecular hydrogen, permeation losses of H2 occur which diffuse through the elastomer seal, 30 As a first aspect, the object of the present inven- tion is therefore to achieve a secure seal of the openings in an electrochemical cell stack with as low costs as possible. 35 This is achieved by an electrochemical compressor system according to the invention. WO 2004/0J6677 PCT/EP2003/011347 4 By providing bead arrangements, which are resilient at least in some regions, for sealing the openings, a secure seal is achieved over a long resilient path of 5 the bead arrangement. Openings are thus understood to mean virtually any region to be sealed in the present application. This may be, for example a passage open ing for a reaction fluid (for example H2 or water) or a cooling agent. However, it may also be, for example 10 the electrochemically active region, in which for ex- ample the gas diffusion layer is arranged or screw holes are provided. The resilient bead arrangement always permits compensation of production tolerances of, for example gas diffusion layers, in a wide tol- 15 erance range and nevertheless provision of an optimum sealing effect, A very advantageous embodiment of the invention en- visages that the bead arrangement is designed for mi- 20 crosealing with a thin coating having a thickness be- tween 1 pm to 400 pm. The coating is advantageously made from an elastomer, such as silicons, viton or EPDM (ethylene/propylene-diene terpolymer), applica- tion is preferably effected by a screen-printing 25 process, tampon-printing process, spraying or by CIPG (cured in place gasket; that is elastomer introduced at the site of the seal as liquid which is cured there.]. These measures ensure that, for example hy- drogen diffusion is reduced to an extremely low de- 30 gree by the seal, since the height of the permeable material is adapted to a minimum. Attempts are thus made not to recover additional geometric height, but only to provide roughness compensation for micro seal- ing, 35 WO2004/036677 PCT/EP2003/011347 5 A further advantageous embodiment of the invention envisages that the bead arrangement contains a full bead or a half bead. It is thus also possible within a bead arrangement to provide both forms, since de- 5 pending on the course of the bead arrangement in the plane, other elasticities may prove useful, for exam- ple that in narrow radii a different beading geometry is useful than for straight courses of the bead ar- rangement . 10 An advantageous development of the bead arrangement envisages that the bead arrangement is designed at least in some regions as a half bead constructed around the electrochemically active region and open 15 around the latter in some regions. It is thus at- tached so that it is open towards the high—pressure side, thus ensuring that by increasing the internal pressure, the increase in contact pressure of the bead against the sealing surface of the next bipolar 20 plate (or the membrane lying therebetween) is achieved. Since the electrochemical compressor stack is stabilised externally by end plates which are held together using tension bands or the like, yielding of the stacked individual plates is only possible to a 25 limited extent. There is no "elastic expansion" of the entire arrangement but only a rise in contact force in regions of the seal so that there is even self-stabilisation of the seals or of the entire ar- rangement. The half bead is thus designed so that by 30 increasing pressure in the system (this internal pressure may be over 200 bar, preferably over 700 bar, particularly preferably over l,000 bar up to 5,000 bar) in the electrochemically active region, surface pressure directed in the direction of the 35 electrochemical compressor stack is increased so that tightness problems are excluded and thus a quas i WO 2004/0366 77 PCT/EP2003/011347 6 "self-stabilising" system is provided with regard to the seal. A further advantageous embodiment envisages that the 5 bead arrangement is made from steel. Steel has the advantage that it can be processed very cost- effectively using conventional tools, in addition, for example methods for coating steel with thin elas- tomer layers are well tested. The good elasticity 10 properties of steel facilitate the good design of the long resilient sealing region of the invention ac- cording to the invention. There is thus the particu- lar possibility that the bead arrangement is attached to the bipolar plate. There is thus firstly the pos- 15 sibility that the bipolar plate is designed as a whole as a steel moulding (which is possibly provided with a coating for corrosion resistance or conductiv- ity in some regions). However, it is also possible that the bipolar plate is designed as a composite 20 elment of two steel plates with a plastic plate ly- ing therebetween. However, in each case the good manufacturing possibilities of steel may be utilised, it is possible to make the bead arrangement within a manufacturing step which is taking place in any case 25 (for example embossing of a flow field, that is a "stream field"). Very low costs are thus produced, also no additional sources of error are provided by extra components, such as for example additionally inserted elastomer seals. 30 Nevertheless, it is also possible according to the invention to provide the bead arrangement made from other metals, such as for example steel, nickel, ti- tanium or aluminium and alloys thereof. The choice, 35 which metal is to be preferred, thus depends, for ex- WO2004/036677 PCT/EP2003/011347 7 ample also on the required electrical properties or the required degree of corrosion resistance. It thus becomes possible to adapt the compression 5 characteristic of the bead, for example to a gas dif- fusion layer. However, this does not have to apply only to gas diffusion layers, the bead line may gen- erally be well adapted to components having low elas- ticity. The beaded seal can be designed flexibly and 10 hence in addition can be applied well and without high retrofitting costs for all producers of electro- chemical compressor systems. A further advantageous embodiment envisages that the 15 bead arrangement has a stopper, which limits compres- sion of the gas diffusion layer to a minimum thick- ness. It is thus an incompressible part of the bead arrangement or a part, the elasticity of which is very much lower than that of the actual bead. This 20 ensures that the degree of deformation is limited in the bead region, so that there cannot be complete flat pressing of the bead. A further advantageous embodiment envisages that the 25 bead arrangement is arranged on a component which is separate from the bipolar plate. This is particularly favourable when the bipolar plates consist of mate- rial which is unsuitable for bead arrangements. The separate component is then placed on the bipolar 30 plate or integrated by adhesion, clicking-in, weld- ing-in, soldering-in or moulding-in, so that overall a sealing connection is produced between the separate component and the bipolar plate. 35 Finally, a further advantageous embodiment envisages that the bead arrangement is designed from an elas- W O/2004/036677 PCT/EP2003/011347 7 ample also on the required electrical properties or the required degree of corrosion resistance. It thus becomes possible to adapt the compression 5 characteristic of the bead, for example to a gas dif- fusion layer. However, this does not have to apply only to gas diffusion layers, the bead line may gen— erally be Well adapted to components having low elas- ticity. The beaded seal can be designed flexibly and 10 hence in addition can be applied well and without high retrofitting costs for all producers of electro- chemical compressor systems. A further advantageous embodiment envisages that the 15 bead arrangement has a stopper, which limits compres- sion of the gas diffusion layer to a minimum thick- ness. It is thus an incompressible part of the bead arrangement or a part, the elasticity of which is very much lower than that of the actual bead. This 20 ensures that the degree of deformation is limited in the bead region, so that there cannot be complete flat pressing of the bead. A further advantageous embodiment envisages that the 25 bead arrangement is arranged on a component which is separate from the bipolar plate. This is particularly favourable when the bipolar plates consist of mate- rial which is unsuitable for bead arrangements. The separate component is then placed on the bipolar 30 plate or integrated by adhesion, clicking-in, weld- ing-in, soldering-in or moulding-in, so that overall a sealing connection is produced between the separate component and the bipolar plate. 35 Finally, a further advantageous embodiment envisages that the bead arrangement is designed from an elas- WO 2004/036677 PCT/EP2003/011347 8 tomer roll. Such a bead can be applied by a screen- printihg process or tampon printing. It serves both for microsealing and for macrosealing. The roll also assumes the function of path adaptation on a gas dif- 5 fusion layer. A further advantageous development envisages that the electrochemical compressor system is designed as an electrolyser. Here, water introduced on one side of 10 the electrochemical cell is cleaved electrochemically into molecular hydrogen and oxygen. Membranes made from Nafion or similar proton-conducting systems are used for this, but separators may also be used, which contain, for example PTFE foams soaked with potassium 15 hydroxide. Also porous ceramic structures, soaked with potassium hydroxide, are possible separators, for example structures based on Nextel or also hy- droxide-conducting structures. The contact forces (surface pressures of the seal in the main direction 20 of the electrochemical cell stack) may lie between 0.1 and 200 N/mm2 , preferably over 10 N/mm2 , particu- larly preferably over 50 N/mm1. A further advantageous development envisages that the 25 electrochemical compressor system is a hydrogen com- pressor, which oxidises molecular hydrogen introduced on the first side of a proton-conducting electro- chemical membrane to H+ and reduces it again on the second side back to molecular hydrogen, wherein the 30 molecular hydrogen there is subjected to a higher pressure on the second side than on the first side due to the sealing and spatial anangement. The. oper- ating temperature should lie here between 0 and 1000C, conceivably also 0 - 2000C or 0 - 550°C. Hy- 35 droxide-conducting structures or even known proton- WO 2004/036677 PCT/EP2003/011347 10 tem) consisting of an electrochemical cell stack (or a fuel cell stack) having layering of several elec- trochemical cells (or fuel cells), which axe sepa- rated from one another in each case by bipolar 5 plates, wherein the bipolar plates have openings for cooling of media supply and media discharge for the electrochemical cells (fuel cells) and the electro- chemical cell stack (or fuel cell stack) can be placed under mechanical compression strain in the di- 10 rection of the layering, wherein resilient bead ar- rangements are provided around the opening of the bi- polar plate, wherein perforations for conducting liq- uid or gaseous media are arranged an at least one flank of the bead arrangements, is thus shown here. 15 It is thus particularly advantageous that first of all sealing of the openings is generally achieved by the bead arrangement when applying a mechanical pres- sure in the direction of layering of the electro- 20 chemical cell stack, which sealing is cost-effective and provides good tolerance compensation. Specific supply or discharge of cooling agents into corre- sponding cooling agent cavities and also secured me- dia supply and media discharge is also additionally 25 facilitated by the perforations in the flanks of the bead arrangements. It is no longer necessary that the bead has to be completely interrupted in order to supply or discharge cooling agents or operating media quasi orthogonally to the direction of layering of 30 the eiectrochamical cell stack (which coincides here with the direction of an interface duct) . Hence it is already possible in the production of these bipolar plates to provide the corresponding perforations which lead Later to media supply in the finished 35 electrochemical compressor system.. It is thus advan- tageous that such perforations can be easily produced W O 2004/036677 PCT/EP2003011347 11 on a large scale, flow resistances and the stiffness of the bead arrangement etc. may be preset precisely by varying the perforations , 5 In particular cost-effective production of a bipolar plate or of parts of the bipolar plate is possible in that a metal plate is provided with holes first of all and then mechanical shaping of the perforated plate takes place to produce the bead arrangement so 10 that the previously introduced holes are perforations in at least one flank of the bead arrangement. Of course it is however also possible to first emboss the profile of the bipolar plate and then to intro- duce the perforations, for example using laser proc- 15 essingr punch supply etc. Hence, it may be said by way of summary that the value of the invention lies in that simplified media supply to the active region of the bipolar plate is 20 possible. "Tunnelling" of a seal is not necessary, since the madia supply in this case takes place through the sealing system itself. This is firstly space-saving and secondly facilitates higher volume and weight capacities of the electrochemical cell. 25 The tinvention is available particularly for metallic bipolar plates for PEM electrochemical cells, which are constructed in most cases from tvo embossed metal sheets which are flatly connected to one another. The media water, in some cases cooling water, and the 30 gases thus have to be effectively sealed with. respect to one another. If the seal of a metallic bipolar plate is designed as a bead construction, the bead is in most cases severely flattened at the points through which media should flow into the active ra- 35 gion. Support for the membrane is not present at these points, which may lead to gas leakages ("cross- WO 2004/036677 PCT/EPZ2003/011347 42 over") or to the collapse of the membrane into the supply channel. However if perforations are intro- duced into the flanks of the bead, and permit the me- dia, for example.hydrogen, air, distilled water, to 5 flow transversely through the bead into the flow field region of the bipolar plats, the bead is able to rest against the membrane uninterrupted. Clean sealing of the media flows is thus achieved. The per- forations may thus be designed more advantageously as 10 circles or also as ovals In order not to noticeably change the spring characteristic of the Dead. Sealing between the fluid flows occurring in the electro- chemical cell is guaranteed by a design of the second metallic plate adapted to the bead construction in 15 the region of media passage. The beads may thus be designed as full beads or half beads. Furthermore, media, passage may take place through the bead with cannected ducts. This is advantageous especially for guiding the cooling medium. .It may thus be guided 20 more easily between the anode and the csthode plates. A further advantageous development envisages that the perforations in the flank plane may have a circular, oval or angular cross-section. The flow properties of 25 fluids guided through these perforations may be in- flueneeri first of all by this shaping and. the sppro- priste number of perforations per flank plane. In ad- dition, the. stiffness of the bead arrangement. can., also thus be controlled for stress in the direction 30 of layering of the electrochemical cell stack, since the corresponding geometrical moments of inertia are also co-influenced by shaping of the perforations. A particularly advantageous development envisages 35 that a duct is connected to a perforation,, wherein the duct is connected to ths bead interior is WO/2004/036677 PCT/EP2003/011347 13 closed at least towards the bead outer-surface. This ensures that the perforations are not guided directly from the bead interior to the outside, but that spe- cific delivery through a duct, for example in the hy- 5 drogen gap of the bipolar plater is possible; the in- troduction of oxygen into the cathode of the electro- chemical cell is thus prevented. It is particularly advantageous in terms of production technology that these ducts may also be co-embossed at the sajne time 10 as embossing of the bipolar plate (when it consists, for example of metal), alternatively, of course the later or earlier attachment of individual ducts is possible. 15 A further development envisages that the perforations ate open towards the electrochemically active region of the electrochemical cell- This is applied in par- ticular to introduce media, such as hydrogen. Of course different variants next to one .another st the 20 same time are also possible in a single bipolar plate, that is those perforations which are connected to ducts and those perforations which have no ducts- An industrially particularly promising embodiment en- 25 visages that the bipolar plate is constructed from two [metal) plates, which has a cavity lying therebe- tween for coding agent and/or passing of media gases, such ss H2. The interior of this bipolar plats may thus also be divided into segments, for example 30 into those which serve on the one hand for guiding cooling agent and on the otner hand for distributing media gases. This segmenting may thus be provided by connecting regions of the two plates, which are de- signed for exampls as a welding or soldering. 35 WO 2(M)4/936677 PCT/EP2003/011347. 14 Figure 2c shows a. plan view of a bipolar plate of the invention; 5 Figures 3a. to 3d show- several bead arrangements with stopper; Figure 4 shows a cutout of an industrially manufac- tured bipolar plate; 10 Figures 5a and 5b show illustration of a bead ar- rangement with perforations; Figures 6a to 6c show illustration of a bead arrange- 15 merit with perforations and ducts connected thereto; Figures 7a to 7c show different types of designs of bead arrangements of the invention. 20 Figure la shows the construction of an electrochemi- cal cell, as shown in Figure lb. A plurality of elec- trochemical cells form in layers the region of an electrochemical cell stack 1 arranged between end plates (see Figure lc). 25 An electrochemical cell 2 with its usual components can be seen in Figure 1a and has for example an ion- conducting polymer membrane, which is provided in the central region 2a with a catalyst layer on both 30 sides. Two bipolar plates 3, between which the poly- mer membrane is arranged, are provided in the elec- trochemical cell. A gas diffusion layer 9, which has dimensions so that it can be accommodated in a recess of the bipolsr plate, is also arranged in the region 35 between each bipolar plate and the polymer membrane (optionalIy, depending on the fina structuring of the WO2001/036677 PCT/EP2003/011347 17 bipols clate) . In the assembled state of the elec- trochemical cell (Figure 1b) , the electrochemically active region of the elecrochemical cells, which is covered essentially by the gas diffusion layer, is 5 arranged in an essentially closed chamber 10 (this corresponds essentially to the recess of the bipolar plate mentioned above), which is limited essentially annularly laterally by a bead 11, This closed chamber IG is gas-tight due to the bead 11, which belongs to 10 a bead arrangement 7 or 7 (see Figures 2aa 2ab,2b). passage openings for media supply Sa and for media discharge 5b lie within the sealing region and are sealed by the bead 11 with respect to further passage 15 openings, for example the passage openings for coal- ing 4 (which have a separate bead for sealing, which is likewise equipped according to the invention). The sealing effect thus takes place on all beads by ex- erting pressure on the electrochemical cell stack 1 20 in direction 6 of the layering (see Figure lc) . This is effected, for example by means of tension bands not shown here. The besd 11 has the advantage that it has a large resilient compression region, in which it shows an adequate sealing effect. This is particu- 25. larly advantageous during installation of the gas diffusion layer 9, which is, for example made from graphite or a metal fibre mat (titanium, stainless steel or nickel), which is produced in industry with high production tolerances. Adaptation of the bead to 30 the geometry of the gas diffusion layer is possible due to the wide resilient region of the bead 11, This ensures that on the one hand lateral sealing is pro- vided, and on the other hand, both adequate gas dis- tribution is provided in the gas diffusion layer 35 plane and in addition the contact pressure in layer- ing direction 6 is uniformly and adequately hign in WO/2004/036677 PCT/EP2003/011347 18 order to achieve uniform stream passage througn the gas diffusion pipe. To improve microsealing, the bead 11 is provided on its outer side with a coating of an elastomer, which has been applied, for example by a 5 screen—printing process. In order to limit pressing of the gas diffusion layer, the bead construction is designed with a. stop- per. This stopper, which may be designed as a fold, 10 as a corrugated stopper or even as a trapezium stop- per, is dealt with once again in more detail further below in the description of Figures 3a to 3d. All stoppers are dedicated to the function that they are able to limit compression of the bead to a minimum 15 dimension- The bipolar plate is designed in the present case as a metal moulding. Reference is made to what has al- ready been said with regard to the ease of production 20 and the advantage of steel in connection with bead arrangements. If the bipolar plate is shaped, for example from a metal which is not suitable for producing suitable 25 bead geometries with the necessary elasticity, the bead region may be designed from a different suitable material (for example steel). Connection of the sepa- rate bead component to the bipolar plate then takes place by joining processes, such as welding, solder- 30 ing, adhesion, riveting, clicking-in. If the bipolar plates are made from a material other than metal, for example from graphite composite, plastic or graphite, the bead region may be designed as a frame from a suitable material. The base material of the bipolar 35 plate, which contains the flow field, is connected to a bead seal frame containing the beads in gas-tight WO2004/036677 PCT/EP2003/011347 12 or liquid-tight manner by joining processes, such as fusing, moulding-in, welding, soldering, adhesion, riveting, clicking-in. 5 figures 2aa and 2ab show embodiments of a bead ar- rangement according to the invention. Figure 2aa shows a cross-section through the bead arrangement 7 which is designed as a half bead. The essentially an- nular bead 11 encloses the gas diffusion layer 9, as 10 already illustrated in the designs of Figure la. In figure 2aa, the bead is designed as a so-called half bead, that is for example like a quadrant. Since the inner region of the electrochemical cell has to be enclosed by a seal, and there are intersections in 15 the region of the media ducta (see Figure 2c) , an al- ternating design as full bead or half bead is neces- sary. A full bead may thus transfer into two half beads, which then in each case have in themselves a sealing effect. In addition, the use of a full bead 20 or half bead provides the possibility of adapting the elasticity in a wide framework. Figure 2aa shows the bead arrangement 7 in the un- pressed state, when exerting mechanical compressive 25 strain on the electrochemical cell stack, pressing takes place in direction 6, so that the bead arrange- ment 7 or the bead 11 forms a gas-tight lateral seal for the closed chamber 10 with regard to the gas dif- fusion layer. 30 Figure 2ab shows a further cutout of the bead ar- rangement 11. It is designed as a half bead. This half bead or bead arrangement in the form of a half. bead is connected to a bipolar plate 3 via a welded 35 seam 27. The membrane 2 is placed on the upper side of the half bead, which is designed essentially to be WO2004/036677 PCT/EP2003/011347 20 "S" shaped- The electrochemically active region is thus enclosed in. gas-tight manner by the membrane 2, the half bead 11 and the bipolar plate, so that an internal pressure Pinternal is provided hers. A gas 5 diffusion layer made from metal fibre mat, in this case titanium fibre mat, is placed in the electro- cbemicelly active region. The helf bead arrangement arranged in this way at least in some regions is de- signed so that the upper flank of the "S" (see also 10 broad arrow) is pushed upwards due to the increased internal pressure Pinternal by a pressure increase in the electrochemically active region and thus the sur- face pressure in this upper flank of the "S'" is in- creased. Since the entire electrochemical cell stack 15 is limited by tension bands to a minimum dimension in the overall extension in the direction of the elec- trochemical cell stack, there is thus an increase in surface pressure here in the region of this flank and hence an even better seal, it is a quasi "self- 20 stabilising system". Figure 2b shows a further bead arrangement, the bead arrangement 7' . The only difference in this arrange- ment from that from Figure 2a consists in that here a 25 bead is designed as a full bead (here approximately with semi-circular cross-section). There are still numerous futher embodiments of the present inven- tion. Hence, it is possible to show, for example still farther bead geometries than those shown here, 30 multiple beads are also possible. In addition, the bead- seal of the invention is possible for all seals in ths iegion of the electrochemicaI cell stack to be pressed. It is not only possible to seal the electro- chemically active region 10 around the gas diffusion 35 layer, but also any passages for gaseous or liquid media etc For the seal around the electrochemical WO2004/036677 PCT/EP2003/011347 21 cell stack assembly guide (screw holes),the elastic- ity Of a besd arrangement may be used in order to counter-control a settling process in the stack and to compensate possible tolerances. 5 Figure 2c shows a plan view of a further embodiment 3' of a bipolar plate of the invention. The bead ar- rangements can thus be seen in plan view by a broad line. The bead arrangements thus serve to seal sev- 10 eral passage openings. Figures 1a to 3d show various bead arrangements which have in. each case a stopper. This stopper serves to limit the deformation of a bead so that it cannot be 15 compressed beyond a certain dimension. Hence, Figure 3a shows a single-layer bead arrange- ment with a full bead 11", the deformation limit of which is reached in direction 15 by a corrugated 20 stopper 29. Figure 3b shows a double-layer bead ar- rangeraent, in which a full bead of the upper layer is limited in deformation by a folded metal sheet lying therebelow (see ref. numeral 34)- Figures 3c and 3d show beaa arrangenent in. which at least two full 25 beads are opposite one another and either a. folded. sheet (see Figure 3c) or a corrugated sheet (see Fig- ure 3d) is provided to limit deformation. Figure 4 shows a detailed structure of a cutout of a 30 bipolar plate 3, which has been illustrated above in principle, using figure la. This bipolar plate can be applied in principle to any electrochemical systems, that is for example to electrochemical compressor systems mentioned above or to fuel cell systems. 35 WO2004/036677 PCT/EP2003/033347 22 The bipolar plate 3 consists of two metal plates 3a and. 3b (the lower plats 3b can be seen in Figure 5b) which are arranged one above another. The plate 3a (the corresponding case applies to plate 3b) has em- 5 bossed duct structures 17 which extend from the plane of the paper upwards. The ducts formed between these projections (indicated by small arrows 18, which show the direction of the duct course) serve for specific passage of gases to the electrochemically active re- 10 gion of the electrochemical cell. The opening 5a or 5b is surrounded by a full bead and serves to supply media, such as H2 or water, to the electrochemically active region. The bead arrangement 15 7 surrounding the opening 5 is thus provided with Hole-like perforations 8, which permit supply of me- dia through the perforations 9 in. the direction of arrows 18. 20 The opening 4 serves to supply cooling liquid to the gap between the plates 3a and 3b. The opening 4 is surrounded by a bead arrangement 7', Ducts 28, which are connected to perforations 8' not shown (see Fig- ure 6a) , go from the bead arrangement into the inte- 25 rior of the bipolar plate 3. Figure 5a shows a cutout of the upper plate 3a of a bipolar plate 3. The bead arrangement 7 is shown in cross-section, which surrounds the opening 5a or 5b. 30 The section corresponds to the section line A-A, as can be seen in -Figure 4. The bead arrangement 7 shows in cross-section a full bead, that is a flank 7b con- necting to a flat region (which surrounds the opening I and which is rising and. after a horizontal piece a 35 falling flank 7a, which is connected to a further horizontal piece. the flanks 7b and 7a thus have cir- WO-2004/036677 PCT/EP/2003/011347 23 culer perforations 8, the supply of gas, for example H2, is indicated by corresponding arrows (they cortex sporid to the arrow direction 18 in Figure 4) . Of course it is also possible to provide oval or angular 5 perforations or only to provide a half bead, in which only a falling flank would be provided starting from a horizontal region. The openings 8 are thus open to- wards the electrochemically active region 10 of the electrochemical cell 2 or the bipolar plate 3, so 10 that a media fluid, such as for example air, H2 or water, may pass here In alternative designs, it. is of course also possible that only one flank, for ex- ample the flank 7a, contains perforations. 15 The plate 3a is made from metal, titanium grade 1, 2, or 4 nickel 200, 201. or 601 and contains the beed arrangement 7 integrally; highly alloyed steels, which are suitable for electrochemical cells, for ex- ample 1.45 71, 1.44 04, 1.44 01 ot 1.44 39, are thus 20 provided as metals. They can also be easily processed on a large scale. Figure 5b shows a bipolar plate 3 in an electrochemi- cal cell stack or a fuel cell or an electrochemical 25 compressor system. A cutout around the opening 5 , which is an "interface" duct is shown An electro- chemical cell 2 to which in turn bipolar plates (in some cases not shown) are connected, is arranged in each case above and below the bipolar plate 3 for 30 better i11ustration, the representation of separata gas diffusion layers was dispensed with. A gas coming through the interface duct passes through the latter essentially in direction 19. The main flow direction in the interface duct is indicated by the arrow 19, 35 further distribution of the gas in the electrochemi- cally active region 25 takes place between upper side WO 2004/036677 PCT/EP/2003/011347 24 of the bipolar plate 3 and electrochemical cell 2 in the direction of arrows 20, and in addition further distribution is possible through the cavity 14 due to appropriate cavity shape of the bipolar plate. The 5 passage of molecular hydrogen on the other flat side of the bipolar plate 3, that is region 21, is also possible in crorresponding manner. Figure 5b additionally shows, how the cavity 14 is 10 separated from a cavity 13 filled with cooling liquid by a joining region 26. Figure 6a. shows a cutout of a bead arrangement 7' which shows the surrounding region of opening 4 (ac- 15 cording to section B-B) , The bead arrangement 7' has in turn a full bead. This full bead has on its flanc 7a' pertoiations 8' to which ducts 2B are connected on the outer side of the 20 bead arrangement. These ducts 28 ensure that a con- nection is provided with the bead interior and hence no gas, which is passed in direction 22, may pass to the bead outer surface 35. 25 Figure 6b shows once again a section through a part of the electrochemical cell stack, and specifically in the region ground an opening 4 (the latter belongs to an interface duct for example for cooling agent, in this case distilled water)- This water flows gen- 30 erally in direction 23, a part stream is separated off in direction 24 to the cavity 13 which, accommo- dates the cooling liquid. It is thus possible to see well in Figure 6b that faultless passage of the cool- ing liquid into, the cavity 13 is provided through the 35 duct 28, which is connected to the perforation 8' , without the region 25 filled with O2 between the WO2004/036677 PCT/EP/2003/111347 25 plate 3a and the electrochemical cell 2 Eying there- above being contaminated with cooling liquid- Figure 6c shows once again a detailed view of the re- 5 gion around the opening 4 in plan view. A correspond- ingly small cutout of the upper plane 3a of bipolar plate 3 is thus shown. It can be seen particularly well that the bead arrangement 7' , to the flank 7a' of which the ducts 28 are connected, which then guide 10 cooling liquid into the cavity 13. (as it were into the plane of the paper) , is provided around the open- ing 4. The bead arrangements of the invention are provided 15 particularly for when bipolar plates having the re- quired tightness can be produced cost-effectively for series production with a very high quality standard. The construction of the bipolar plates having inte- gral bead arrangements is thus provided in particu- 20 lar. It. is thus possible to produce the bead arrange- ments integrally from a sheet metal part, for example by embossing [for example at the same time for em- bossing of the duct structure), very low production costs thus result. In particular it is not necessary 25 to adapt additional components for sealing, the posi- tioning of which may be expensive. Figures 7a to 7c show different embodiments of bead arrangements - All thsse bead arrangements can be ap- 30 plied to the bead arrangements mentioned above to de- fine the electrochemically active region, or openinigs and perforations. For the sake of a better overview, the latter are nevertheless designated below by new reference numbers 30 - 33. 35 WO2004/036677 PCT/EP2003/011347 26 Figure 7a shows first of ali the different possible modifications of beed arrangements in 3D position, by way of example. This concerns specific courses fat full beads (see for example Fig. 2b with bead ar- 5 rangement 7' or Figs. 5a (bead arrangement 7) or 5a (bead arrangement 7') , Corresponding courses are also applicable Us full beads, Concerning further details, attention is drawn to the above-said. 10 The bead arrangement 33 thus shows a bead of variable material thickness. Cross-sections of the bead ar- rangement are shown as A-A or B-B [see Fig, 7c) . Here A-A shews a material thickness of M2, in cross- section B-B a material thickness of M1 is shown. In 15 Fig. 7b f characterises a region which represents the shortest distance of two identical points in the re- peating structure. As the regions within the repeat- ing structures may relate to stiff and less stiff re- gions , whose length ratios may be variable, the 20 stiffer region hers is designated "l". (The above definition of the frequency also applies to the ar- rangements 30 to 32). Bead arrangement 32 shows a corrugated course of the 25 bead arrangements. For the corrugated course the fre- quency f can also be selected here, likewise the am- plitude AMP and the radius R (see Fig, 7b) , wherein the pressure distribution or compression stiffness of the bipolar plate can be selected due to this corru- 30 gated design. The bead arrangement 31 shows a variable bar width which may likewise be supplied with any frequency f. "Barwidth" is thus understood to mean the outer width 35 of the upper flat section corresponding to the bar width "stb" defined in Figure 7c- For the bead ar- PCT/EPO3/11547 REINZ-Dichrungs-Gmbh Amended Claims 5 1. electrochemical compressor system for compress- ing gases and/or for producing gases by elec- trolysis, consisting of an electrochemical com- pressor stack (1) having layering of several 10 electrochemical cells, which sre separated from one another in each case by bipolar plates (3; 3') , wherein the bipolar plates have openings for media supply and media discharge (5a, 5b) for the electrochemical cells and the electro- 15 chemical cell stack can be placed under mechani- cal compressive strain in direction (6) of the layering, characterised in that bead arrange- ments (7; 7') which are resilient are provided at least in some regions to seal the openings 20 (4, 5a, 5b) and/or an electrochemically active region (10) of the electrochemical cells and that the bead arrangement is made from metals. 2. Electrochemical compressor system according to claim 1, characterised. in that the electrochemi- 25 cal cells have gas diffusion layers (9) made from conductive structures, such as metal fi- bres , on their sides facing the bipolar plates. 3. Electrochemical compressor system according to one of the preceding claims, characterised in 30 that the bead arrangement (7; T' ) is coated to microseal media. 4. Electrochemical compressor system according to claim 3, characterised in that coating is ef- 29 fected using an elastomer. 5. Electrochemical Compressor system according to one of ciaims 3 or 4, characterised in that Coating is effected by means of screen-printing 5 processes, tampon printing, spraying or CIPG. 6. Electrochemical compressor system according to one of the preceding claims, characterised in that the bead arrangement {7; 7') contains a full bead or a half bead. 10 7. Electrachemical compressor system according to one of the preceding claims, characterised in that the bead arrangement (7; 7') is made from steel, nickel, titanium, aluminium, and alloys haying a high proportion of these metals• 15 8, Electrochemical compressor system according to one cf the preceding claims, characterised in that the bead arrangement has a stopper which limits compression of the gas diffusion layer to 20 9. Electrochemical compressor system according to one of the preceding claims, characterised in that the bead arrangement (7; l') is connected to the bipolar plate (3; 3' ) . 10. Electrochemical compressor system accocding to 25 claim B, characterised in that the bipolar plate (3; 3') is designed as a whole as a metal mould- ing . 11. Electrochemical compressor system according to one of the preceding claims, characterised in 30 that the bead arrangement is arranged on a cam- ponent which is separate from. the bipolar plate, 30 which component is placed on graphite, plastic, metal or the like or integrated by adhesion, clicking-in, welding-in, sol-dering-in er mould- ing-in. 5 12. Electrochemical compressor system according to claim. 8, characterised in that the bipolar plate (3; 3') is designed as a composite element of two metal plates having a plastic plate lying therebetween. 10 13, Electrochemical compressor system according to one of the preceding claims, characterised in that the electrochemically active region of the electrochemical cells is arranged in an essen- tially closed chamber (10), which is limited es- 15 sentially annularly laterally by the bead ar- rangement. 14. Electrochemical compressor system according to claim 13, characterised in that the bead ar- rangement is designed or least in some regions 20 as a half bead which is open, towards the elec- trochemically active region/closed chamber (10). 15. Electrochemical compressor system, according to one of the preceding claims, characterised in that the bead arrangement is designed as an 25 elastomer roll which is applied by screen or tampon printing or moulded on as a roll. 16. Electrochemical compressaor system according to one of the preceding claims, characterised in that it is an electrolyses which cleaves water 30 introduced on one side of the electrochemical cell electrochemically into molecular hydrogen and oxygen. 31 17 Electrochemical comprassor system according to one of the preceding claims characterised in that it is a hydrogen compressor, which oxidises molecular hydrogen introduced on the first side 5 of a proton-conducting electrochemical cell to H+ and reduces it again on the second side back to molecular hydrogen, wherein the molecular hy- drogen there is subjected to a higher pressure on the second side than on the first side due to .10 the sealing and spatial arrangement. 18. Electrochemical compressor system according to one of the preceding claims, characterised in that the gas pressure in the electrochemically active region is sealed off so that the gas 15 pressure prevailing there in the closed chamber (10) without leakage losses may be over 100 bar, preferably over 200 bar, particularly preferably over 500 bar . 19. Electrochemical compressor system according to 20 one of the preceding claims, characterised in that resilient bead arrangements (7, 7') are provided around the openings (4; 5) of the bipo- lar plate and/or the electrochemically active region, wherein perforations (8, 8') for con- 25 ducting liquid or gaseous media are arranged on at least one flank (7a, 7a'} of the bead ar- rangements. 20. Electrochemical compressor system according to claim 19, characterised in that the perforations 30 (8, 8' ) are circular, oval or angular. 21. Electrochemical compressor system according to one of claims. 19 or 20, characterised in that a duct (28) is connected to a perforation (8'), 32 which are sepatated from one another in esch case by bipolar plates (3), wherein the bipolor pistes have openings for cooling (4) or medis supply and media discharge (5a;5b) for the fuel 5 ells and the fuel ceil stack can be placed un- der mechanical compression strain in direction {6} of the layering, characterised in that re- silient bead arrangements (7, 7') are provided around the openings (8, 8') of the bipolar plate, 10 wherein perforations (8, 8') for conducting liq- uid or gaseous media are arranged on at least one flank (7a, 7a') of the bead arrangements and that the bead arrangements are made from metals, 29. Fuel cell system according to claim 28, charac- 15 Cerised in that the perforations [8, 8') are circular, oval or angular, 30 Fuel cell system according to one of claims 28 or 29, chaeacterised in. that a duct (20) is, con- nected to a perforatiom (8'), wherein the duct 20 is connected, to the beading interior (10') and. is clased at least towards the beading outer surface. 31. Fuei cell system according to one of claims 28 or 29, characterised in that the perforations 25 (8) are open towards the electrochemically ac- tive region (10) of the fuel cell. 32. Fuel cell system according to one of claims 28 to 31, characterised in that the bipolar plate (3) is constructed from two plates [3a, 3b) , 30 which have a cavity (13;14) lying therebetween for cooling agent and/or conducting media gases . 33. Fuel cell system according to one of claim 28 to 38 characterised in that the. bead arrange- 33 mer: (7, 7') contains a full bead or a half bead. 34. Fuel cell system according to claim 33, charac- terised ir that the full bead contains perfora- 5 tions (8) on one (7a) or on both flanks (7a,- 7b) . 35. Fuel cell system according to one of claims 28 to 34, characterised in that the bead arrange- ment {7; 7') consists of steel, nickel, titanium 10 or aluiminium. 36, Fuel cell system according to one of claims 28 to 35, characteried in that the bead arrange- ment (7, 7') is part of a plate (3a) belonging to the bipolar plate. 15 37. Fuel cell system according to one of claims 28 to 35, characterised in that the bead arrange- ment is arranged on a component which, is sepa- rate from the bipolac plate, which component is placed on bipolar plates made from graphite, 20 plastic, metal or the like or connected to the bipolar plate by adhesion, clicking-in, weldinn- in, soldering-in or moulding-in, 38. Fuel cell system according to one of claims 28 to 37 characterised in that the bead arrange 25 ment (7; 7') is coated to microseal media. 39. Fuel cell system according to one of claims 28 to 33, characterised in that an electrochemi- cally active region of the fuel cell is arranged in an essentially closed chamber (10) , which is 30 limited essentially annularly laterally by a bead arrangement- 34 41. Fusi cell system according to one of claim 28 to 39, characterised in that the bead arrsnge- ment- (7, 7') has essentially the same stiffness fox stressed in direction. (6) of the Layering in 5 the perforated and the non-perforated flank re- gions . 41, Bipolar plate for a fuel cell system according to one of claims 28 to 40. 42. process for produing a bipolox plate according 10 to claim 27 or according to claim 41, character- ised in that a metal plate is provided with holes first of all and then mechanical shaping of the perforated plate takes place to produce the-bead arrangement so that the holes are per- 15 forations in at least one flank of the bead ar- rangement. The invention deals with! art electrochemical system for compressing gases and/or forproducing gases by elecrolsis. consisong of an electrochemical-compressor'stack; (1) having layering of Several electrochemical, which are separated fram one another in each case by bipalor plates (5; 3') wherein the bipalor plats have opening. for media supply and media dischange (Ja. 5b) fur the electrochemical cells and the electrochemical cell stack tan be pioced under mechanical compresive stain in direction (6) of the layering. The bead arrangement (7; 7") are resident-and are provided at least in some regions to seal the openings (4, 5a. 5b) and/or an electrochemically active region (10) of the electrochemical cell.

Full Text

Electrochemical system
The present invention relates to an electrochemical
system, such as for example a fuel cell system or an
5 electrochemical compressor system.
Electrochemical compressor systems may be, for exam-
ple eleotrolysers, which by applying a potential, in
addition to producing, for example water and oxygen
10 from water, compress these gases at the same time un-
der high pressure.
In addition, electrochemical compressor systems, such
as for example electrochemical hydrogen compressors,
15 are also known, to which gaseous molecular hydrogen
is supplied and the latter is compressed electro-
chemically by applying a potential. This electro-
chemical compression is available particularly for
small quantities of hydrogen to be compressed, since

WO 2004/036677 PCT/EP2003/011347
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mechanical compression of hydrogen would be consid-
erably more expensive here.
Electrochemical systems are known, in which an elsc-
5 trochemical cell stack is constructed with layering
of several electrochemical cells, which are separated
from one another in each case by bipolar plates. The
bipolar plates thus have several tasks:
10 - electrical contacting of the electrodes of the
individual electrochemical cells and conveying the
current to the adjacent cell series connection of
the cells,
- supplying the cells with reactants, such as for
15 example water or gases and, for example removal of
the reaction gas produced via an appropriate dis-
tributor structure,
- conveying the heat being produced during genera-
tion in the electrochemical cell, and
20 - sealing off of the various media ducts or cool-
ing ducts with respect to one another and externally.
The bipolar plates have openings for cooling or media
supply and media discharge for media supply and media
25 discharge from the bipolar plates to the actual elec-
trochemical cells (these are for example MEA (Mem-
brane Electron Assembly) having a gas diffusion
layer, for example made from a metal mat, orientated
in each case towards the bipolar plates).
30
Difficulties regularly result here particularly with
regard to the gas diffusion layer. It has been con-
ventional hitherto to design the seal between the bi-
polar plates or -between bipolar plates and the elec-
35 trochemical cell in that an elastomer seal is placed,
for example in a groove of the bipolar plate. By ex-

WO 2004/036677 PCT/EP2003/011347
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erting compressive strain (for example by means of
tension bands) on the electrochemical cell stack,
pressing of the seal then takes place, as a result of
which a sealing effect should be achieved for the
5 openings -
It is now a problem for the inserted gas diffusion
layer that it may be designed as a fibre mat (with
metal fibres) or metal mesh. Fibre mats which are
10 conventional in industry have a theoretical thickness
of, for example l mm, but the manufacturing tolerance
is + 100 pm. The metal fibres which construct the mat
are themselves only slightly resilient. In addition,
it is also not recommended to compensate production
15 tolerances of the fibre mat by compressing the mat,
since the gas permeability of the mat layer is thus
severely diminished and hence operation of the elec-
trochemical cell is restricted. On the other hand
however, it is necessary to exert a minimum pressure
20 on the entire gas diffusion layer by the bipolar
plate, so that there is an adequate passage of cur-
rent through the gas diffusion layer. It can thus be
summarised that for the current elastomer seals, ei-
ther a non-perfect seal or non-optimum operation of
25 the electrochemical cell was thus to be accepted. In
addition, particularly for electrochemical cells op-
erated using molecular hydrogen, permeation losses of
H2 occur which diffuse through the elastomer seal,
30 As a first aspect, the object of the present inven-
tion is therefore to achieve a secure seal of the
openings in an electrochemical cell stack with as low
costs as possible.
35 This is achieved by an electrochemical compressor
system according to the invention.

WO 2004/0J6677 PCT/EP2003/011347
4
By providing bead arrangements, which are resilient
at least in some regions, for sealing the openings, a
secure seal is achieved over a long resilient path of
5 the bead arrangement. Openings are thus understood to
mean virtually any region to be sealed in the present
application. This may be, for example a passage open
ing for a reaction fluid (for example H2 or water) or
a cooling agent. However, it may also be, for example
10 the electrochemically active region, in which for ex-
ample the gas diffusion layer is arranged or screw
holes are provided. The resilient bead arrangement
always permits compensation of production tolerances
of, for example gas diffusion layers, in a wide tol-
15 erance range and nevertheless provision of an optimum
sealing effect,
A very advantageous embodiment of the invention en-
visages that the bead arrangement is designed for mi-
20 crosealing with a thin coating having a thickness be-
tween 1 pm to 400 pm. The coating is advantageously
made from an elastomer, such as silicons, viton or
EPDM (ethylene/propylene-diene terpolymer), applica-
tion is preferably effected by a screen-printing
25 process, tampon-printing process, spraying or by CIPG
(cured in place gasket; that is elastomer introduced
at the site of the seal as liquid which is cured
there.]. These measures ensure that, for example hy-
drogen diffusion is reduced to an extremely low de-
30 gree by the seal, since the height of the permeable
material is adapted to a minimum. Attempts are thus
made not to recover additional geometric height, but
only to provide roughness compensation for micro seal-
ing,
35

WO2004/036677 PCT/EP2003/011347
5
A further advantageous embodiment of the invention
envisages that the bead arrangement contains a full
bead or a half bead. It is thus also possible within
a bead arrangement to provide both forms, since de-
5 pending on the course of the bead arrangement in the
plane, other elasticities may prove useful, for exam-
ple that in narrow radii a different beading geometry
is useful than for straight courses of the bead ar-
rangement .
10
An advantageous development of the bead arrangement
envisages that the bead arrangement is designed at
least in some regions as a half bead constructed
around the electrochemically active region and open
15 around the latter in some regions. It is thus at-
tached so that it is open towards the high—pressure
side, thus ensuring that by increasing the internal
pressure, the increase in contact pressure of the
bead against the sealing surface of the next bipolar
20 plate (or the membrane lying therebetween) is
achieved. Since the electrochemical compressor stack
is stabilised externally by end plates which are held
together using tension bands or the like, yielding of
the stacked individual plates is only possible to a
25 limited extent. There is no "elastic expansion" of
the entire arrangement but only a rise in contact
force in regions of the seal so that there is even
self-stabilisation of the seals or of the entire ar-
rangement. The half bead is thus designed so that by
30 increasing pressure in the system (this internal
pressure may be over 200 bar, preferably over 700
bar, particularly preferably over l,000 bar up to
5,000 bar) in the electrochemically active region,
surface pressure directed in the direction of the
35 electrochemical compressor stack is increased so that
tightness problems are excluded and thus a quas
i

WO 2004/0366 77 PCT/EP2003/011347
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"self-stabilising" system is provided with regard to
the seal.
A further advantageous embodiment envisages that the
5 bead arrangement is made from steel. Steel has the
advantage that it can be processed very cost-
effectively using conventional tools, in addition,
for example methods for coating steel with thin elas-
tomer layers are well tested. The good elasticity
10 properties of steel facilitate the good design of the
long resilient sealing region of the invention ac-
cording to the invention. There is thus the particu-
lar possibility that the bead arrangement is attached
to the bipolar plate. There is thus firstly the pos-
15 sibility that the bipolar plate is designed as a
whole as a steel moulding (which is possibly provided
with a coating for corrosion resistance or conductiv-
ity in some regions). However, it is also possible
that the bipolar plate is designed as a composite
20 elment of two steel plates with a plastic plate ly-
ing therebetween. However, in each case the good
manufacturing possibilities of steel may be utilised,
it is possible to make the bead arrangement within a
manufacturing step which is taking place in any case
25 (for example embossing of a flow field, that is a
"stream field"). Very low costs are thus produced,
also no additional sources of error are provided by
extra components, such as for example additionally
inserted elastomer seals.
30
Nevertheless, it is also possible according to the
invention to provide the bead arrangement made from
other metals, such as for example steel, nickel, ti-
tanium or aluminium and alloys thereof. The choice,
35 which metal is to be preferred, thus depends, for ex-

WO2004/036677 PCT/EP2003/011347
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ample also on the required electrical properties or
the required degree of corrosion resistance.
It thus becomes possible to adapt the compression
5 characteristic of the bead, for example to a gas dif-
fusion layer. However, this does not have to apply
only to gas diffusion layers, the bead line may gen-
erally be well adapted to components having low elas-
ticity. The beaded seal can be designed flexibly and
10 hence in addition can be applied well and without
high retrofitting costs for all producers of electro-
chemical compressor systems.
A further advantageous embodiment envisages that the
15 bead arrangement has a stopper, which limits compres-
sion of the gas diffusion layer to a minimum thick-
ness. It is thus an incompressible part of the bead
arrangement or a part, the elasticity of which is
very much lower than that of the actual bead. This
20 ensures that the degree of deformation is limited in
the bead region, so that there cannot be complete
flat pressing of the bead.
A further advantageous embodiment envisages that the
25 bead arrangement is arranged on a component which is
separate from the bipolar plate. This is particularly
favourable when the bipolar plates consist of mate-
rial which is unsuitable for bead arrangements. The
separate component is then placed on the bipolar
30 plate or integrated by adhesion, clicking-in, weld-
ing-in, soldering-in or moulding-in, so that overall
a sealing connection is produced between the separate
component and the bipolar plate.
35 Finally, a further advantageous embodiment envisages
that the bead arrangement is designed from an elas-

W O/2004/036677 PCT/EP2003/011347
7
ample also on the required electrical properties or
the required degree of corrosion resistance.
It thus becomes possible to adapt the compression
5 characteristic of the bead, for example to a gas dif-
fusion layer. However, this does not have to apply
only to gas diffusion layers, the bead line may gen—
erally be Well adapted to components having low elas-
ticity. The beaded seal can be designed flexibly and
10 hence in addition can be applied well and without
high retrofitting costs for all producers of electro-
chemical compressor systems.
A further advantageous embodiment envisages that the
15 bead arrangement has a stopper, which limits compres-
sion of the gas diffusion layer to a minimum thick-
ness. It is thus an incompressible part of the bead
arrangement or a part, the elasticity of which is
very much lower than that of the actual bead. This
20 ensures that the degree of deformation is limited in
the bead region, so that there cannot be complete
flat pressing of the bead.
A further advantageous embodiment envisages that the
25 bead arrangement is arranged on a component which is
separate from the bipolar plate. This is particularly
favourable when the bipolar plates consist of mate-
rial which is unsuitable for bead arrangements. The
separate component is then placed on the bipolar
30 plate or integrated by adhesion, clicking-in, weld-
ing-in, soldering-in or moulding-in, so that overall
a sealing connection is produced between the separate
component and the bipolar plate.
35 Finally, a further advantageous embodiment envisages
that the bead arrangement is designed from an elas-

WO 2004/036677 PCT/EP2003/011347
8
tomer roll. Such a bead can be applied by a screen-
printihg process or tampon printing. It serves both
for microsealing and for macrosealing. The roll also
assumes the function of path adaptation on a gas dif-
5 fusion layer.
A further advantageous development envisages that the
electrochemical compressor system is designed as an
electrolyser. Here, water introduced on one side of
10 the electrochemical cell is cleaved electrochemically
into molecular hydrogen and oxygen. Membranes made
from Nafion or similar proton-conducting systems are
used for this, but separators may also be used, which
contain, for example PTFE foams soaked with potassium
15 hydroxide. Also porous ceramic structures, soaked
with potassium hydroxide, are possible separators,
for example structures based on Nextel or also hy-
droxide-conducting structures. The contact forces
(surface pressures of the seal in the main direction
20 of the electrochemical cell stack) may lie between
0.1 and 200 N/mm2 , preferably over 10 N/mm2 , particu-
larly preferably over 50 N/mm1.
A further advantageous development envisages that the
25 electrochemical compressor system is a hydrogen com-
pressor, which oxidises molecular hydrogen introduced
on the first side of a proton-conducting electro-
chemical membrane to H+ and reduces it again on the
second side back to molecular hydrogen, wherein the
30 molecular hydrogen there is subjected to a higher
pressure on the second side than on the first side
due to the sealing and spatial anangement. The. oper-
ating temperature should lie here between 0 and
1000C, conceivably also 0 - 2000C or 0 - 550°C. Hy-
35 droxide-conducting structures or even known proton-

WO 2004/036677 PCT/EP2003/011347
10
tem) consisting of an electrochemical cell stack (or
a fuel cell stack) having layering of several elec-
trochemical cells (or fuel cells), which axe sepa-
rated from one another in each case by bipolar
5 plates, wherein the bipolar plates have openings for
cooling of media supply and media discharge for the
electrochemical cells (fuel cells) and the electro-
chemical cell stack (or fuel cell stack) can be
placed under mechanical compression strain in the di-
10 rection of the layering, wherein resilient bead ar-
rangements are provided around the opening of the bi-
polar plate, wherein perforations for conducting liq-
uid or gaseous media are arranged an at least one
flank of the bead arrangements, is thus shown here.
15
It is thus particularly advantageous that first of
all sealing of the openings is generally achieved by
the bead arrangement when applying a mechanical pres-
sure in the direction of layering of the electro-
20 chemical cell stack, which sealing is cost-effective
and provides good tolerance compensation. Specific
supply or discharge of cooling agents into corre-
sponding cooling agent cavities and also secured me-
dia supply and media discharge is also additionally
25 facilitated by the perforations in the flanks of the
bead arrangements. It is no longer necessary that the
bead has to be completely interrupted in order to
supply or discharge cooling agents or operating media
quasi orthogonally to the direction of layering of
30 the eiectrochamical cell stack (which coincides here
with the direction of an interface duct) . Hence it is
already possible in the production of these bipolar
plates to provide the corresponding perforations
which lead Later to media supply in the finished
35 electrochemical compressor system.. It is thus advan-
tageous that such perforations can be easily produced

W O 2004/036677 PCT/EP2003011347
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on a large scale, flow resistances and the stiffness
of the bead arrangement etc. may be preset precisely
by varying the perforations ,
5 In particular cost-effective production of a bipolar
plate or of parts of the bipolar plate is possible in
that a metal plate is provided with holes first of
all and then mechanical shaping of the perforated
plate takes place to produce the bead arrangement so
10 that the previously introduced holes are perforations
in at least one flank of the bead arrangement. Of
course it is however also possible to first emboss
the profile of the bipolar plate and then to intro-
duce the perforations, for example using laser proc-
15 essingr punch supply etc.
Hence, it may be said by way of summary that the
value of the invention lies in that simplified media
supply to the active region of the bipolar plate is
20 possible. "Tunnelling" of a seal is not necessary,
since the madia supply in this case takes place
through the sealing system itself. This is firstly
space-saving and secondly facilitates higher volume
and weight capacities of the electrochemical cell.
25 The tinvention is available particularly for metallic
bipolar plates for PEM electrochemical cells, which
are constructed in most cases from tvo embossed metal
sheets which are flatly connected to one another. The
media water, in some cases cooling water, and the
30 gases thus have to be effectively sealed with. respect
to one another. If the seal of a metallic bipolar
plate is designed as a bead construction, the bead is
in most cases severely flattened at the points
through which media should flow into the active ra-
35 gion. Support for the membrane is not present at
these points, which may lead to gas leakages ("cross-

WO 2004/036677 PCT/EPZ2003/011347
42
over") or to the collapse of the membrane into the
supply channel. However if perforations are intro-
duced into the flanks of the bead, and permit the me-
dia, for example.hydrogen, air, distilled water, to
5 flow transversely through the bead into the flow
field region of the bipolar plats, the bead is able
to rest against the membrane uninterrupted. Clean
sealing of the media flows is thus achieved. The per-
forations may thus be designed more advantageously as
10 circles or also as ovals In order not to noticeably
change the spring characteristic of the Dead. Sealing
between the fluid flows occurring in the electro-
chemical cell is guaranteed by a design of the second
metallic plate adapted to the bead construction in
15 the region of media passage. The beads may thus be
designed as full beads or half beads. Furthermore,
media, passage may take place through the bead with
cannected ducts. This is advantageous especially for
guiding the cooling medium. .It may thus be guided
20 more easily between the anode and the csthode plates.
A further advantageous development envisages that the
perforations in the flank plane may have a circular,
oval or angular cross-section. The flow properties of
25 fluids guided through these perforations may be in-
flueneeri first of all by this shaping and. the sppro-
priste number of perforations per flank plane. In ad-
dition, the. stiffness of the bead arrangement. can.,
also thus be controlled for stress in the direction
30 of layering of the electrochemical cell stack, since
the corresponding geometrical moments of inertia are
also co-influenced by shaping of the perforations.
A particularly advantageous development envisages
35 that a duct is connected to a perforation,, wherein
the duct is connected to ths bead interior is

WO/2004/036677 PCT/EP2003/011347
13
closed at least towards the bead outer-surface. This
ensures that the perforations are not guided directly
from the bead interior to the outside, but that spe-
cific delivery through a duct, for example in the hy-
5 drogen gap of the bipolar plater is possible; the in-
troduction of oxygen into the cathode of the electro-
chemical cell is thus prevented. It is particularly
advantageous in terms of production technology that
these ducts may also be co-embossed at the sajne time
10 as embossing of the bipolar plate (when it consists,
for example of metal), alternatively, of course the
later or earlier attachment of individual ducts is
possible.
15 A further development envisages that the perforations
ate open towards the electrochemically active region
of the electrochemical cell- This is applied in par-
ticular to introduce media, such as hydrogen. Of
course different variants next to one .another st the
20 same time are also possible in a single bipolar
plate, that is those perforations which are connected
to ducts and those perforations which have no ducts-
An industrially particularly promising embodiment en-
25 visages that the bipolar plate is constructed from
two [metal) plates, which has a cavity lying therebe-
tween for coding agent and/or passing of media
gases, such ss H2. The interior of this bipolar plats
may thus also be divided into segments, for example
30 into those which serve on the one hand for guiding
cooling agent and on the otner hand for distributing
media gases. This segmenting may thus be provided by
connecting regions of the two plates, which are de-
signed for exampls as a welding or soldering.
35

WO 2(M)4/936677 PCT/EP2003/011347.
14
Figure 2c shows a. plan view of a bipolar plate of the
invention;
5 Figures 3a. to 3d show- several bead arrangements with
stopper;
Figure 4 shows a cutout of an industrially manufac-
tured bipolar plate;
10
Figures 5a and 5b show illustration of a bead ar-
rangement with perforations;
Figures 6a to 6c show illustration of a bead arrange-
15 merit with perforations and ducts connected thereto;
Figures 7a to 7c show different types of designs of
bead arrangements of the invention.
20 Figure la shows the construction of an electrochemi-
cal cell, as shown in Figure lb. A plurality of elec-
trochemical cells form in layers the region of an
electrochemical cell stack 1 arranged between end
plates (see Figure lc).
25
An electrochemical cell 2 with its usual components
can be seen in Figure 1a and has for example an ion-
conducting polymer membrane, which is provided in the
central region 2a with a catalyst layer on both
30 sides. Two bipolar plates 3, between which the poly-
mer membrane is arranged, are provided in the elec-
trochemical cell. A gas diffusion layer 9, which has
dimensions so that it can be accommodated in a recess
of the bipolsr plate, is also arranged in the region
35 between each bipolar plate and the polymer membrane
(optionalIy, depending on the fina structuring of the

WO2001/036677 PCT/EP2003/011347
17
bipols clate) . In the assembled state of the elec-
trochemical cell (Figure 1b) , the electrochemically
active region of the elecrochemical cells, which is
covered essentially by the gas diffusion layer, is
5 arranged in an essentially closed chamber 10 (this
corresponds essentially to the recess of the bipolar
plate mentioned above), which is limited essentially
annularly laterally by a bead 11, This closed chamber
IG is gas-tight due to the bead 11, which belongs to
10 a bead arrangement 7 or 7 (see Figures 2aa 2ab,2b).
passage openings for media supply Sa and for media
discharge 5b lie within the sealing region and are
sealed by the bead 11 with respect to further passage
15 openings, for example the passage openings for coal-
ing 4 (which have a separate bead for sealing, which
is likewise equipped according to the invention). The
sealing effect thus takes place on all beads by ex-
erting pressure on the electrochemical cell stack 1
20 in direction 6 of the layering (see Figure lc) . This
is effected, for example by means of tension bands
not shown here. The besd 11 has the advantage that it
has a large resilient compression region, in which it
shows an adequate sealing effect. This is particu-
25. larly advantageous during installation of the gas
diffusion layer 9, which is, for example made from
graphite or a metal fibre mat (titanium, stainless
steel or nickel), which is produced in industry with
high production tolerances. Adaptation of the bead to
30 the geometry of the gas diffusion layer is possible
due to the wide resilient region of the bead 11, This
ensures that on the one hand lateral sealing is pro-
vided, and on the other hand, both adequate gas dis-
tribution is provided in the gas diffusion layer
35 plane and in addition the contact pressure in layer-
ing direction 6 is uniformly and adequately hign in

WO/2004/036677 PCT/EP2003/011347
18
order to achieve uniform stream passage througn the
gas diffusion pipe. To improve microsealing, the bead
11 is provided on its outer side with a coating of an
elastomer, which has been applied, for example by a
5 screen—printing process.
In order to limit pressing of the gas diffusion
layer, the bead construction is designed with a. stop-
per. This stopper, which may be designed as a fold,
10 as a corrugated stopper or even as a trapezium stop-
per, is dealt with once again in more detail further
below in the description of Figures 3a to 3d. All
stoppers are dedicated to the function that they are
able to limit compression of the bead to a minimum
15 dimension-
The bipolar plate is designed in the present case as
a metal moulding. Reference is made to what has al-
ready been said with regard to the ease of production
20 and the advantage of steel in connection with bead
arrangements.
If the bipolar plate is shaped, for example from a
metal which is not suitable for producing suitable
25 bead geometries with the necessary elasticity, the
bead region may be designed from a different suitable
material (for example steel). Connection of the sepa-
rate bead component to the bipolar plate then takes
place by joining processes, such as welding, solder-
30 ing, adhesion, riveting, clicking-in. If the bipolar
plates are made from a material other than metal, for
example from graphite composite, plastic or graphite,
the bead region may be designed as a frame from a
suitable material. The base material of the bipolar
35 plate, which contains the flow field, is connected to
a bead seal frame containing the beads in gas-tight

WO2004/036677 PCT/EP2003/011347
12
or liquid-tight manner by joining processes, such as
fusing, moulding-in, welding, soldering, adhesion,
riveting, clicking-in.
5 figures 2aa and 2ab show embodiments of a bead ar-
rangement according to the invention. Figure 2aa
shows a cross-section through the bead arrangement 7
which is designed as a half bead. The essentially an-
nular bead 11 encloses the gas diffusion layer 9, as
10 already illustrated in the designs of Figure la. In
figure 2aa, the bead is designed as a so-called half
bead, that is for example like a quadrant. Since the
inner region of the electrochemical cell has to be
enclosed by a seal, and there are intersections in
15 the region of the media ducta (see Figure 2c) , an al-
ternating design as full bead or half bead is neces-
sary. A full bead may thus transfer into two half
beads, which then in each case have in themselves a
sealing effect. In addition, the use of a full bead
20 or half bead provides the possibility of adapting the
elasticity in a wide framework.
Figure 2aa shows the bead arrangement 7 in the un-
pressed state, when exerting mechanical compressive
25 strain on the electrochemical cell stack, pressing
takes place in direction 6, so that the bead arrange-
ment 7 or the bead 11 forms a gas-tight lateral seal
for the closed chamber 10 with regard to the gas dif-
fusion layer.
30
Figure 2ab shows a further cutout of the bead ar-
rangement 11. It is designed as a half bead. This
half bead or bead arrangement in the form of a half.
bead is connected to a bipolar plate 3 via a welded
35 seam 27. The membrane 2 is placed on the upper side
of the half bead, which is designed essentially to be

WO2004/036677 PCT/EP2003/011347
20
"S" shaped- The electrochemically active region is
thus enclosed in. gas-tight manner by the membrane 2,
the half bead 11 and the bipolar plate, so that an
internal pressure Pinternal is provided hers. A gas
5 diffusion layer made from metal fibre mat, in this
case titanium fibre mat, is placed in the electro-
cbemicelly active region. The helf bead arrangement
arranged in this way at least in some regions is de-
signed so that the upper flank of the "S" (see also
10 broad arrow) is pushed upwards due to the increased
internal pressure Pinternal by a pressure increase in
the electrochemically active region and thus the sur-
face pressure in this upper flank of the "S'" is in-
creased. Since the entire electrochemical cell stack
15 is limited by tension bands to a minimum dimension in
the overall extension in the direction of the elec-
trochemical cell stack, there is thus an increase in
surface pressure here in the region of this flank and
hence an even better seal, it is a quasi "self-
20 stabilising system".
Figure 2b shows a further bead arrangement, the bead
arrangement 7' . The only difference in this arrange-
ment from that from Figure 2a consists in that here a
25 bead is designed as a full bead (here approximately
with semi-circular cross-section). There are still
numerous futher embodiments of the present inven-
tion. Hence, it is possible to show, for example
still farther bead geometries than those shown here,
30 multiple beads are also possible. In addition, the
bead- seal of the invention is possible for all seals
in ths iegion of the electrochemicaI cell stack to be
pressed. It is not only possible to seal the electro-
chemically active region 10 around the gas diffusion
35 layer, but also any passages for gaseous or liquid
media etc For the seal around the electrochemical

WO2004/036677 PCT/EP2003/011347
21
cell stack assembly guide (screw holes),the elastic-
ity Of a besd arrangement may be used in order to
counter-control a settling process in the stack and
to compensate possible tolerances.
5
Figure 2c shows a plan view of a further embodiment
3' of a bipolar plate of the invention. The bead ar-
rangements can thus be seen in plan view by a broad
line. The bead arrangements thus serve to seal sev-
10 eral passage openings.
Figures 1a to 3d show various bead arrangements which
have in. each case a stopper. This stopper serves to
limit the deformation of a bead so that it cannot be
15 compressed beyond a certain dimension.
Hence, Figure 3a shows a single-layer bead arrange-
ment with a full bead 11", the deformation limit of
which is reached in direction 15 by a corrugated
20 stopper 29. Figure 3b shows a double-layer bead ar-
rangeraent, in which a full bead of the upper layer is
limited in deformation by a folded metal sheet lying
therebelow (see ref. numeral 34)- Figures 3c and 3d
show beaa arrangenent in. which at least two full
25 beads are opposite one another and either a. folded.
sheet (see Figure 3c) or a corrugated sheet (see Fig-
ure 3d) is provided to limit deformation.
Figure 4 shows a detailed structure of a cutout of a
30 bipolar plate 3, which has been illustrated above in
principle, using figure la. This bipolar plate can be
applied in principle to any electrochemical systems,
that is for example to electrochemical compressor
systems mentioned above or to fuel cell systems.
35

WO2004/036677 PCT/EP2003/033347
22
The bipolar plate 3 consists of two metal plates 3a
and. 3b (the lower plats 3b can be seen in Figure 5b)
which are arranged one above another. The plate 3a
(the corresponding case applies to plate 3b) has em-
5 bossed duct structures 17 which extend from the plane
of the paper upwards. The ducts formed between these
projections (indicated by small arrows 18, which show
the direction of the duct course) serve for specific
passage of gases to the electrochemically active re-
10 gion of the electrochemical cell.
The opening 5a or 5b is surrounded by a full bead and
serves to supply media, such as H2 or water, to the
electrochemically active region. The bead arrangement
15 7 surrounding the opening 5 is thus provided with
Hole-like perforations 8, which permit supply of me-
dia through the perforations 9 in. the direction of
arrows 18.
20 The opening 4 serves to supply cooling liquid to the
gap between the plates 3a and 3b. The opening 4 is
surrounded by a bead arrangement 7', Ducts 28, which
are connected to perforations 8' not shown (see Fig-
ure 6a) , go from the bead arrangement into the inte-
25 rior of the bipolar plate 3.
Figure 5a shows a cutout of the upper plate 3a of a
bipolar plate 3. The bead arrangement 7 is shown in
cross-section, which surrounds the opening 5a or 5b.
30 The section corresponds to the section line A-A, as
can be seen in -Figure 4. The bead arrangement 7 shows
in cross-section a full bead, that is a flank 7b con-
necting to a flat region (which surrounds the opening
I and which is rising and. after a horizontal piece a
35 falling flank 7a, which is connected to a further
horizontal piece. the flanks 7b and 7a thus have cir-

WO-2004/036677 PCT/EP/2003/011347
23
culer perforations 8, the supply of gas, for example
H2, is indicated by corresponding arrows (they cortex
sporid to the arrow direction 18 in Figure 4) . Of
course it is also possible to provide oval or angular
5 perforations or only to provide a half bead, in which
only a falling flank would be provided starting from
a horizontal region. The openings 8 are thus open to-
wards the electrochemically active region 10 of the
electrochemical cell 2 or the bipolar plate 3, so
10 that a media fluid, such as for example air, H2 or
water, may pass here In alternative designs, it. is
of course also possible that only one flank, for ex-
ample the flank 7a, contains perforations.
15 The plate 3a is made from metal, titanium grade 1, 2,
or 4 nickel 200, 201. or 601 and contains the beed
arrangement 7 integrally; highly alloyed steels,
which are suitable for electrochemical cells, for ex-
ample 1.45 71, 1.44 04, 1.44 01 ot 1.44 39, are thus
20 provided as metals. They can also be easily processed
on a large scale.
Figure 5b shows a bipolar plate 3 in an electrochemi-
cal cell stack or a fuel cell or an electrochemical
25 compressor system. A cutout around the opening 5 ,
which is an "interface" duct is shown An electro-
chemical cell 2 to which in turn bipolar plates (in
some cases not shown) are connected, is arranged in
each case above and below the bipolar plate 3 for
30 better i11ustration, the representation of separata
gas diffusion layers was dispensed with. A gas coming
through the interface duct passes through the latter
essentially in direction 19. The main flow direction
in the interface duct is indicated by the arrow 19,
35 further distribution of the gas in the electrochemi-
cally active region 25 takes place between upper side

WO 2004/036677 PCT/EP/2003/011347
24
of the bipolar plate 3 and electrochemical cell 2 in
the direction of arrows 20, and in addition further
distribution is possible through the cavity 14 due to
appropriate cavity shape of the bipolar plate. The
5 passage of molecular hydrogen on the other flat side
of the bipolar plate 3, that is region 21, is also
possible in crorresponding manner.
Figure 5b additionally shows, how the cavity 14 is
10 separated from a cavity 13 filled with cooling liquid
by a joining region 26.
Figure 6a. shows a cutout of a bead arrangement 7'
which shows the surrounding region of opening 4 (ac-
15 cording to section B-B) ,
The bead arrangement 7' has in turn a full bead. This
full bead has on its flanc 7a' pertoiations 8' to
which ducts 2B are connected on the outer side of the
20 bead arrangement. These ducts 28 ensure that a con-
nection is provided with the bead interior and hence
no gas, which is passed in direction 22, may pass to
the bead outer surface 35.
25 Figure 6b shows once again a section through a part
of the electrochemical cell stack, and specifically
in the region ground an opening 4 (the latter belongs
to an interface duct for example for cooling agent,
in this case distilled water)- This water flows gen-
30 erally in direction 23, a part stream is separated
off in direction 24 to the cavity 13 which, accommo-
dates the cooling liquid. It is thus possible to see
well in Figure 6b that faultless passage of the cool-
ing liquid into, the cavity 13 is provided through the
35 duct 28, which is connected to the perforation 8' ,
without the region 25 filled with O2 between the

WO2004/036677 PCT/EP/2003/111347
25
plate 3a and the electrochemical cell 2 Eying there-
above being contaminated with cooling liquid-
Figure 6c shows once again a detailed view of the re-
5 gion around the opening 4 in plan view. A correspond-
ingly small cutout of the upper plane 3a of bipolar
plate 3 is thus shown. It can be seen particularly
well that the bead arrangement 7' , to the flank 7a'
of which the ducts 28 are connected, which then guide
10 cooling liquid into the cavity 13. (as it were into
the plane of the paper) , is provided around the open-
ing 4.
The bead arrangements of the invention are provided
15 particularly for when bipolar plates having the re-
quired tightness can be produced cost-effectively for
series production with a very high quality standard.
The construction of the bipolar plates having inte-
gral bead arrangements is thus provided in particu-
20 lar. It. is thus possible to produce the bead arrange-
ments integrally from a sheet metal part, for example
by embossing [for example at the same time for em-
bossing of the duct structure), very low production
costs thus result. In particular it is not necessary
25 to adapt additional components for sealing, the posi-
tioning of which may be expensive.
Figures 7a to 7c show different embodiments of bead
arrangements - All thsse bead arrangements can be ap-
30 plied to the bead arrangements mentioned above to de-
fine the electrochemically active region, or openinigs
and perforations. For the sake of a better overview,
the latter are nevertheless designated below by new
reference numbers 30 - 33.
35

WO2004/036677 PCT/EP2003/011347
26
Figure 7a shows first of ali the different possible
modifications of beed arrangements in 3D position, by
way of example. This concerns specific courses fat
full beads (see for example Fig. 2b with bead ar-
5 rangement 7' or Figs. 5a (bead arrangement 7) or 5a
(bead arrangement 7') , Corresponding courses are also
applicable Us full beads, Concerning further details,
attention is drawn to the above-said.
10 The bead arrangement 33 thus shows a bead of variable
material thickness. Cross-sections of the bead ar-
rangement are shown as A-A or B-B [see Fig, 7c) . Here
A-A shews a material thickness of M2, in cross-
section B-B a material thickness of M1 is shown. In
15 Fig. 7b f characterises a region which represents the
shortest distance of two identical points in the re-
peating structure. As the regions within the repeat-
ing structures may relate to stiff and less stiff re-
gions , whose length ratios may be variable, the
20 stiffer region hers is designated "l". (The above
definition of the frequency also applies to the ar-
rangements 30 to 32).
Bead arrangement 32 shows a corrugated course of the
25 bead arrangements. For the corrugated course the fre-
quency f can also be selected here, likewise the am-
plitude AMP and the radius R (see Fig, 7b) , wherein
the pressure distribution or compression stiffness of
the bipolar plate can be selected due to this corru-
30 gated design.
The bead arrangement 31 shows a variable bar width
which may likewise be supplied with any frequency f.
"Barwidth" is thus understood to mean the outer width
35 of the upper flat section corresponding to the bar
width "stb" defined in Figure 7c- For the bead ar-

PCT/EPO3/11547
REINZ-Dichrungs-Gmbh
Amended Claims
5
1. electrochemical compressor system for compress-
ing gases and/or for producing gases by elec-
trolysis, consisting of an electrochemical com-
pressor stack (1) having layering of several
10 electrochemical cells, which sre separated from
one another in each case by bipolar plates (3;
3') , wherein the bipolar plates have openings
for media supply and media discharge (5a, 5b)
for the electrochemical cells and the electro-
15 chemical cell stack can be placed under mechani-
cal compressive strain in direction (6) of the
layering, characterised in that bead arrange-
ments (7; 7') which are resilient are provided
at least in some regions to seal the openings
20 (4, 5a, 5b) and/or an electrochemically active
region (10) of the electrochemical cells and
that the bead arrangement is made from metals.
2. Electrochemical compressor system according to
claim 1, characterised. in that the electrochemi-
25 cal cells have gas diffusion layers (9) made
from conductive structures, such as metal fi-
bres , on their sides facing the bipolar plates.
3. Electrochemical compressor system according to
one of the preceding claims, characterised in
30 that the bead arrangement (7; T' ) is coated to
microseal media.
4. Electrochemical compressor system according to
claim 3, characterised in that coating is ef-

29
fected using an elastomer.
5. Electrochemical Compressor system according to
one of ciaims 3 or 4, characterised in that
Coating is effected by means of screen-printing
5 processes, tampon printing, spraying or CIPG.
6. Electrochemical compressor system according to
one of the preceding claims, characterised in
that the bead arrangement {7; 7') contains a
full bead or a half bead.
10 7. Electrachemical compressor system according to
one of the preceding claims, characterised in
that the bead arrangement (7; 7') is made from
steel, nickel, titanium, aluminium, and alloys
haying a high proportion of these metals•
15 8, Electrochemical compressor system according to
one cf the preceding claims, characterised in
that the bead arrangement has a stopper which
limits compression of the gas diffusion layer to
20 9. Electrochemical compressor system according to
one of the preceding claims, characterised in
that the bead arrangement (7; l') is connected
to the bipolar plate (3; 3' ) .
10. Electrochemical compressor system accocding to
25 claim B, characterised in that the bipolar plate
(3; 3') is designed as a whole as a metal mould-
ing .
11. Electrochemical compressor system according to
one of the preceding claims, characterised in
30 that the bead arrangement is arranged on a cam-
ponent which is separate from. the bipolar plate,

30
which component is placed on graphite, plastic,
metal or the like or integrated by adhesion,
clicking-in, welding-in, sol-dering-in er mould-
ing-in.
5 12. Electrochemical compressor system according to
claim. 8, characterised in that the bipolar plate
(3; 3') is designed as a composite element of
two metal plates having a plastic plate lying
therebetween.
10 13, Electrochemical compressor system according to
one of the preceding claims, characterised in
that the electrochemically active region of the
electrochemical cells is arranged in an essen-
tially closed chamber (10), which is limited es-
15 sentially annularly laterally by the bead ar-
rangement.
14. Electrochemical compressor system according to
claim 13, characterised in that the bead ar-
rangement is designed or least in some regions
20 as a half bead which is open, towards the elec-
trochemically active region/closed chamber (10).
15. Electrochemical compressor system, according to
one of the preceding claims, characterised in
that the bead arrangement is designed as an
25 elastomer roll which is applied by screen or
tampon printing or moulded on as a roll.
16. Electrochemical compressaor system according to
one of the preceding claims, characterised in
that it is an electrolyses which cleaves water
30 introduced on one side of the electrochemical
cell electrochemically into molecular hydrogen
and oxygen.

31
17 Electrochemical comprassor system according to
one of the preceding claims characterised in
that it is a hydrogen compressor, which oxidises
molecular hydrogen introduced on the first side
5 of a proton-conducting electrochemical cell to
H+ and reduces it again on the second side back
to molecular hydrogen, wherein the molecular hy-
drogen there is subjected to a higher pressure
on the second side than on the first side due to
.10 the sealing and spatial arrangement.
18. Electrochemical compressor system according to
one of the preceding claims, characterised in
that the gas pressure in the electrochemically
active region is sealed off so that the gas
15 pressure prevailing there in the closed chamber
(10) without leakage losses may be over 100 bar,
preferably over 200 bar, particularly preferably
over 500 bar .
19. Electrochemical compressor system according to
20 one of the preceding claims, characterised in
that resilient bead arrangements (7, 7') are
provided around the openings (4; 5) of the bipo-
lar plate and/or the electrochemically active
region, wherein perforations (8, 8') for con-
25 ducting liquid or gaseous media are arranged on
at least one flank (7a, 7a'} of the bead ar-
rangements.
20. Electrochemical compressor system according to
claim 19, characterised in that the perforations
30 (8, 8' ) are circular, oval or angular.
21. Electrochemical compressor system according to
one of claims. 19 or 20, characterised in that a
duct (28) is connected to a perforation (8'),

32
which are sepatated from one another in esch
case by bipolar plates (3), wherein the bipolor
pistes have openings for cooling (4) or medis
supply and media discharge (5a;5b) for the fuel
5 ells and the fuel ceil stack can be placed un-
der mechanical compression strain in direction
{6} of the layering, characterised in that re-
silient bead arrangements (7, 7') are provided
around the openings (8, 8') of the bipolar plate,
10 wherein perforations (8, 8') for conducting liq-
uid or gaseous media are arranged on at least
one flank (7a, 7a') of the bead arrangements and
that the bead arrangements are made from metals,
29. Fuel cell system according to claim 28, charac-
15 Cerised in that the perforations [8, 8') are
circular, oval or angular,
30 Fuel cell system according to one of claims 28
or 29, chaeacterised in. that a duct (20) is, con-
nected to a perforatiom (8'), wherein the duct
20 is connected, to the beading interior (10') and.
is clased at least towards the beading outer
surface.
31. Fuei cell system according to one of claims 28
or 29, characterised in that the perforations
25 (8) are open towards the electrochemically ac-
tive region (10) of the fuel cell.
32. Fuel cell system according to one of claims 28
to 31, characterised in that the bipolar plate
(3) is constructed from two plates [3a, 3b) ,
30 which have a cavity (13;14) lying therebetween
for cooling agent and/or conducting media gases .
33. Fuel cell system according to one of claim 28
to 38 characterised in that the. bead arrange-

33
mer: (7, 7') contains a full bead or a half
bead.
34. Fuel cell system according to claim 33, charac-
terised ir that the full bead contains perfora-
5 tions (8) on one (7a) or on both flanks (7a,-
7b) .
35. Fuel cell system according to one of claims 28
to 34, characterised in that the bead arrange-
ment {7; 7') consists of steel, nickel, titanium
10 or aluiminium.
36, Fuel cell system according to one of claims 28
to 35, characteried in that the bead arrange-
ment (7, 7') is part of a plate (3a) belonging
to the bipolar plate.
15 37. Fuel cell system according to one of claims 28
to 35, characterised in that the bead arrange-
ment is arranged on a component which, is sepa-
rate from the bipolac plate, which component is
placed on bipolar plates made from graphite,
20 plastic, metal or the like or connected to the
bipolar plate by adhesion, clicking-in, weldinn-
in, soldering-in or moulding-in,
38. Fuel cell system according to one of claims 28
to 37 characterised in that the bead arrange
25 ment (7; 7') is coated to microseal media.
39. Fuel cell system according to one of claims 28
to 33, characterised in that an electrochemi-
cally active region of the fuel cell is arranged
in an essentially closed chamber (10) , which is
30 limited essentially annularly laterally by a
bead arrangement-

34
41. Fusi cell system according to one of claim 28
to 39, characterised in that the bead arrsnge-
ment- (7, 7') has essentially the same stiffness
fox stressed in direction. (6) of the Layering in
5 the perforated and the non-perforated flank re-
gions .
41, Bipolar plate for a fuel cell system according
to one of claims 28 to 40.
42. process for produing a bipolox plate according
10 to claim 27 or according to claim 41, character-
ised in that a metal plate is provided with
holes first of all and then mechanical shaping
of the perforated plate takes place to produce
the-bead arrangement so that the holes are per-
15 forations in at least one flank of the bead ar-
rangement.

The invention deals with! art electrochemical system for compressing gases and/or forproducing gases by elecrolsis.
consisong of an electrochemical-compressor'stack; (1) having layering of Several electrochemical, which are separated fram one
another in each case by bipalor plates (5; 3') wherein the bipalor plats have opening. for media supply and media dischange (Ja.
5b) fur the electrochemical cells and the electrochemical cell stack tan be pioced under mechanical compresive stain in direction
(6) of the layering. The bead arrangement (7; 7") are resident-and are provided at least in some regions to seal the openings (4, 5a.
5b) and/or an electrochemically active region (10) of the electrochemical cell.

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Patent Number

218580

Indian Patent Application Number

00901/KOLNP/2005

PG Journal Number

14/2008

Publication Date

04-Apr-2008

Grant Date

02-Apr-2008

Date of Filing

17-May-2005

Name of Patentee

REINZ-DICHTUNGS-GMBH

Applicant Address

REINZSTRASSE 3-7,89233 NEW-ULM,GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	RAIMUND STRÖBEL	GARTENSTR. 15 89077 ULM/GERMANY
2	GAUGLER,BERND	KOHLGASSE 15 89073 ULM/GERMANY
3	SAILER,ALDRECHT	BGM.-LOPP-STR. 4 89233 NEU-ULM/GERMANY
4	KUNZ,CLAUDIA	NEUA STR. 125 89073 ULM/GERMANY
5	SCHERER,JOACHIM	SACHSENWEG 67 89075 ULM/GERMANY
6	SCHLEIER,CHRISTIAN	WASSERBURGER WEG 123 89312 GUNZBURG/GERMANY
7	WALDVOGEL,JOHANN	AUGSBURGER STR. 35K 86381 KRUMBACH/GERMANY

PCT International Classification Number

H01M 8/02, 8/10

PCT International Application Number

PCT/EP03/011347

PCT International Filing date

2003-10-14

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	203 08 3326	2003-05-22	Germany
2	102 48 531.3	2002-10-14	Germany