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Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cell StacksDissolution of ruthenium was observed in the 80-cell stack. Duration testing was performed in single cell MEAs to determine the pathway of cell degradation. EDAX analysis on each of the single cell MEAs has shown that the Johnson Matthey commercial catalyst is stable in DMFC operation for 250 hours, no ruthenium dissolution was observed. Changes in the hydrophobicity of the cathode backing papers was minimum. Electrode polarization analysis revealed that the MEA performance loss is attributed to changes in the cathode catalyst layer. Ruthenium migration does not seem to occur during cell operation but can occur when methanol is absent from the anode compartment, the cathode compartment has access to air, and the cells in the stack are electrically connected to a load (Shunt Currents). The open-to-air cathode stack design allowed for: a) The MEAs to have continual access to oxygen; and b) The stack to sustain shunt currents. Ruthenium dissolution in a DMFC stack can be prevented by: a) Developing an internally manifolded stacks that seal reactant compartments when not in operation; b) Bringing the cell voltages to zero quickly when not in operation; and c) Limiting the total number of cells to 25 in an effort to limit shunt currents.
Document ID
20070013771
Document Type
Conference Paper
External Source(s)
Authors
Valdez, Thomas I. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Firdosy, S. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Koel, B. E. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Narayanan, S. R. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 23, 2013
Publication Date
October 19, 2005
Subject Category
Propellants and Fuels
Meeting Information
208th Meeting of the Electrochemical Society (ECS)(Los Angeles, CA)
Distribution Limits
Public
Copyright
Other
Keywords
alternative power sources
fuel cells
methanol