# US 7,608,118 B2 · Preconditioning fuel cell membrane electrode assemblies > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,118 B2 - Document ID: US7608118B2 - Status: Granted - Kind: B2 - Application number: 10/988,811 - Filed: 2004-11-15 - Published: 2006-05-18 - Granted: 2009-10-27 - Earliest claimed: 2004-11-15 - Assignees: 3M Innovative Properties Company - Inventors: Bradley P. Anderson - Web page: https://patentgrep.com/patent/US7608118B2 ## CPC - H01M 8/1004: characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) - H01M 8/04302: applied during start-up - H01M 8/04126: {Humidifying} - Y02E 60/50: Fuel cells - Y10T 29/49108: Electric battery cell making - Y10T 29/4911: including sealing - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method is presented for preconditioning fuel cell membrane electrode assemblies for use in fuel cell systems which includes exposure to saturated steam at superatmospheric pressures, typically for at least 10 minutes and more typically at least 25 minutes. Typically, the preconditioning method according to the present invention results in reduction of the start up or conditioning time required when the MEA's are first installed in a fuel cell system and improvement of overall performance, as reflected in the achievement of high current density at relatively high voltage. The method may additionally include the step of enclosing the fuel cell membrane electrode assembly in a container which is substantially impervious to water before the fuel cell membrane electrode assembly returns to ambient temperature. ## Claims ### Claim 1 A method of preconditioning a fuel cell membrane electrode assembly comprising the steps of: a) providing a fuel cell membrane electrode assembly; and b) exposing the fuel cell membrane electrode assembly to saturated steam at a treatment pressure which is at least 110 kPa. ### Claim 2 (depends on 1) The method according to claim 1 wherein the treatment pressure is at least 130 kPa. ### Claim 3 (depends on 1) The method according to claim 1 wherein the treatment pressure is at least 170 kPa. ### Claim 4 (depends on 1) The method according to claim 1 wherein the treatment pressure is at least 200 kPa. ### Claim 5 (depends on 4) The method according to claim 4 wherein step b) has a duration which is at least 10 minutes. ### Claim 6 (depends on 4) The method according to claim 4 wherein step b) has a duration which is at least 25 minutes. ### Claim 7 (depends on 6) The method according to claim 6, additionally comprising the step of: c) enclosing the fuel cell membrane electrode assembly in a container within 96 hours after step b). ### Claim 8 (depends on 6) The method according to claim 6, additionally comprising the step of: d) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water within 96 hours after step b). ### Claim 9 (depends on 6) The method according to claim 6, additionally comprising the step of: e) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water within 1 hour after step b). ### Claim 10 (depends on 6) The method according to claim 6, additionally comprising the step of: f) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water after step b) but before the fuel cell membrane electrode assembly returns to ambient temperature. ### Claim 11 (depends on 6) The method according to claim 6, additionally comprising the step of: g) enclosing the fuel cell membrane electrode assembly in a container which includes a humidifying element within 96 hours after step b). ### Claim 12 (depends on 6) The method according to claim 6, additionally comprising the step of: h) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water which includes a humidifying element after step b) but before the fuel cell membrane electrode assembly returns to ambient temperature. ### Claim 13 (depends on 1) The method according to claim 1 wherein step b) has a duration which is at least 10 minutes. ### Claim 14 (depends on 1) The method according to claim 1 wherein step b) has a duration which is at least 25 minutes. ### Claim 15 (depends on 1) The method according to claim 1, additionally comprising the step of: c) enclosing the fuel cell membrane electrode assembly in a container within 96 hours after step b). ### Claim 16 (depends on 1) The method according to claim 1, additionally comprising the step of: d) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water within 96 hours after step b). ### Claim 17 (depends on 1) The method according to claim 1, additionally comprising the step of: e) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water within 1 hour after step b). ### Claim 18 (depends on 1) The method according to claim 1, additionally comprising the step of: f) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water after step b) but before the fuel cell membrane electrode assembly returns to ambient temperature. ### Claim 19 (depends on 1) The method according to claim 1, additionally comprising the step of: g) enclosing the fuel cell membrane electrode assembly in a container which includes a humidifying element within 96 hours after step b). ### Claim 20 (depends on 1) The method according to claim 1, additionally comprising the step of: h) enclosing the fuel cell membrane electrode assembly in a container substantially impervious to water which includes a humidifying element after step b) but before the fuel cell membrane electrode assembly returns to ambient temperature.