High Performance PEM Fuel Cells - From Electrochemistry and Material Science to Engineering Development of a Multicell Stack.
Quarterly rept. no. 6, Apr-Jun 96,
TEXAS A AND M UNIV COLLEGE STATION
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To increase the electrocatalytic activity of the air electrode and simultaneously minimize the transport limitations, mixture of a 10 wt. alloy supported on carbon and a high platinum loading 40 wt. on carbon was used as the electrocatalyst. The presence of the alloy electrocatalyst enhances the electrocatalytic activity at low current densities and the presence of the Pt electrocatalyst preserves the open structure of the electrode in this way the performance enhancement is evident over the entire range of current densities. This experiment was repeated with 20 micrometers thick GORE-SELECT TM membrane and a similar effect was observed. One 3-cell stack of area 50 sq cm was assembled at BCS Technology, Inc. with MEAs prepared using a Nafion 112 membrane and electrodes containing a Pt loading of 4.5 mgsq cm. At 2.1 V 0.7 V per cell, the current density was about 0.48 Asq cm with air and about 0.65 Asq cm with oxygen. The cells required slight pressurization on the air side of the cell. The performance of the third cell was found to be slightly lower, and required a rapid flow flushing of hydrogen periodically. This problem did not result from the quality of the MEAs used, but was probably due to a design problem associated with stacking or the internal manifolding. The stack was tested at CESHR for performance verification and approximately the same performance was observed as that at BCS. However, problems similar to those noted at BCS were also seen at CESHR.
- Physical Chemistry
- Electrochemical Energy Storage
- Properties of Metals and Alloys