# US 6,720,104 B2 · PEM fuel cell stack > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,104 B2 - Document ID: US6720104B2 - Status: Granted - Kind: B2 - Application number: 09/933,121 - Filed: 2001-08-21 - Published: 2002-05-02 - Granted: 2004-04-13 - Earliest claimed: 2001-08-21 - Assignees: dmc2 Degussa Metals Catalysts Cerdec AG - Inventors: Ralf Zuber; Armin Bayer; Heike Kühnhold; Udo Stenke - Web page: https://patentgrep.com/patent/US6720104B2 ## CPC - H01M 8/0263: having meandering or serpentine paths - B60L 50/72: Constructional details of fuel cells specially adapted for electric vehicles - H01M 8/0234: Carbonaceous material - H01M 8/0271: Sealing or supporting means around electrodes, matrices or membranes - H01M 8/1007: with both reactants being gaseous or vaporised (H01M8/12 takes precedence) - H01M 8/242: comprising framed electrodes or intermediary frame-like gaskets (H01M8/2425, H01M8/244 take precedence) - B60L 2240/36: Temperature of vehicle components or parts - H01M 8/0273: with sealing or supporting means in the form of a frame - H01M 8/0282: Inorganic material - H01M 8/2457: with both reactants being gaseous or vaporised - H01M 8/248: Means for compression of the fuel cell stacks - Y02E 60/50: Fuel cells - Y02T 90/40: Application of hydrogen technology to transportation, e.g. using fuel cells - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A PEM fuel cell stack including one or more fuel cells (1) arranged on top of one another, each of which contains a membrane electrode assembly (2) between two electrically conductive bipolar plates (3,4), the surfaces of which are equipped with flow channels (10) open on one side for the supply of reactive gases, whereby the membrane electrode assemblies each comprise a polymer electrolyte membrane (5), both sides of which are in contact with a reaction layer (6,7), whereby the surface area of the reaction layers is smaller than that of the polymer electrolyte membrane and a compressible, coarse-pore gas distribution layer (8,9) made from carbon fiber fabric is inserted between each reaction layer and the adjacent bipolar plates congruent to the reaction lawyers along with seals (11,12) in the area outside the surface covered by the gas distribution layers, whereby the gas distribution layers in the no-load condition display a thickness D1 and the seals a thickness D2. The PEM fuel cell stack is featured by the gas distribution layers in the PEM fuel cell stack being compressed to 25 to 60% of the original thickness. ## Claims ### Claim 1 PEM fuel cell stack comprising a plurality of fuel cells arranged on top of one another, each of said fuel cells contains a membrane electrode assembly between the surfaces of two electrically conductive bipolar plates, said surfaces containing a plurality of flow channels open on one side for the supply of reactive gases, the membrane electrode assembly comprises a polymer electrolyte membrane each side of which is in contact with a reaction layer, each such reaction layer having a surface area smaller than that of the polymer electrolyte membrane, a compressible, coarse-pore gas distribution layer made from carbon fiber fabric being positioned between each reaction layer and the adjacent bipolar plates congruent to the reaction layers, there being seals in an area between said plates outside the surface covered by the gas distribution layers, whereby the gas distribution layers in the no-load condition display a thickness D1 and the seals a thickness D2, said gas distribution layers in the PEM fuel cell stack being compressed to 25 to 60% of their original thickness. ### Claim 2 (depends on 1) PEM fuel cell stack according to claim 1, wherein the seals consist of non-compressible material and the compression of the fuel cell stack is obtained by the ratio D2/D1. ### Claim 3 (depends on 2) PEM fuel cell stack according to claim 2, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 20 to 70° to the flow channels on the bipolar plates. ### Claim 4 (depends on 2) PEM fuel cell stack according to claim 2, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 30 to 60° to the flow channels on the bipolar plates. ### Claim 5 (depends on 2) PEM fuel cell stack according to claim 2, wherein the carbon fiber fabric is woven in a structure such that at least 60% of the fibers display an angle of at least 30° to the channel structure of the bipolar plates. ### Claim 6 (depends on 1) PEM fuel cell stack according to claim 1, wherein the porosity of the gas distribution layers used is reduced by compression to 20 to 70% and their electrical resistance to below 6 mΩ cm. ### Claim 7 (depends on 6) PEM fuel cell stack according to claim 6, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 20 to 70° to the flow channels on the bipolar plates. ### Claim 8 (depends on 6) PEM fuel cell stack according to claim 6, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 30 to 60° to the flow channels on the bipolar plates. ### Claim 9 (depends on 6) PEM fuel cell stack according to claim 6, wherein the carbon fiber fabric is woven in a structure such that at least 60% of the fibers display an angle of at least 30° to the channel structure of the bipolar plates. ### Claim 10 (depends on 1) PEM fuel cell stack according to claim 1, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 20 to 70° to the flow channels on the bipolar plates. ### Claim 11 (depends on 1) PEM fuel cell stack according to claim 1, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 30 to 60° to the flow channels on the bipolar plates. ### Claim 12 (depends on 1) PEM fuel cell stack according to claim 1, wherein the carbon fiber fabric is woven in a structure such that at least 60% of the fibers display an angle of at least 30° to the channel structure of the bipolar plates. ### Claim 13 (depends on 1) Electric car containing a PEM fuel cell stack for electrical energy supply, which includes a PEM fuel stack according to claim 1. ### Claim 14 A PEM fuel cell comprising a membrane electrode assembly between the surfaces of two electrically conductive bipolar plates, said surfaces containing a plurality of flow channels open on one side for the supply of reactive gases, the membrane electrode assembly comprises a polymer electrolyte membrane, each side of which is in contact with a reaction layer, each such reaction layer having a surface area smaller than that of the polymer electrolyte membrane, a compressible, coarse-pore gas distribution layer made from carbon fiber fabric being positioned between each reaction layer and the adjacent bipolar plates congruent to the reaction layers, there being seals in an area between said plates outside the surface covered by the gas distribution layers, whereby the gas distribution layers in the no-load condition display a thickness D1 and the seals a thickness D2, said gas distribution layers in the PEM fuel cell stack being compressed to 25 to 60% of their original thickness. ### Claim 15 (depends on 14) The PEM fuel cell according to claim 14, wherein the seals consist of non-compressible material and the compression of the fuel cell stack is obtained by the ratio D2.D1. ### Claim 16 (depends on 14) The PEM fuel cell according to claim 14, wherein the porosity of the gas distribution layers used is reduced by compression to 20 to 70% and their electrical resistance to below 6 mΩ cm. ### Claim 17 (depends on 14) The PEM fuel cell according to claim 14, wherein the weave direction of the carbon fiber fabric is oriented at an angel of 20 to 70° to the flow channels on the bipolar plates. ### Claim 18 (depends on 17) The PEM fuel cell according to claim 17, wherein the weave direction of the carbon fiber fabric is oriented at an angle of 30 to 60° to the flow channels on the bipolar plates. ### Claim 19 A method of assembly a PEM fuel cell stack formed of a plurality of fuel cells arranged on tope of one another, each of which contains a membrane electrode assembly between two electrically conductive bipolar plates, the surfaces of which are equipped with flow channels open on one side for the supply of reactive gases, whereby the membrane electrode assemblies each comprise a polymer electrolyte membrane, both sides of which are in contact with a reaction layer, whereby the surface area of the reaction layers is smaller than that of the polymer electrolyte membrane and a compressible, coarse-pore gas distribution layer made from carbon fiber fabric is inserted between each reaction layer and the adjacent bipolar plates congruent to the reaction layers along with seals in the area outside the surface covered by the gas distribution layers, whereby the gas distribution layers in the no-load condition display a thickness D1 and the seals a thickness D2, comprising stacking at least two of said fuel cells together and compressing a stack of said fuel cells in a direction perpendicular to the polymer electrolyte membrane such that the gas distribution layers in the PEM fuel cell stack are compressed to 25 to 60% of their original thickness.