Accession Number : ADA324712

Title :   High Performance PEM Fuel Cells - From Electrochemistry and Material Science to Engineering Development of a Multicell Stack.

Descriptive Note : Quarterly rept. no. 6, Apr-Jun 96,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION

Personal Author(s) : Appleyby, A. J. ; Srinivasan, Supramaniam

PDF Url : ADA324712

Report Date : 16 AUG 1996

Pagination or Media Count : 17

Abstract : 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 mg/sq cm. At 2.1 V (0.7 V per cell), the current density was about 0.48 A/sq cm with air and about 0.65 A/sq 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.

Descriptors :   *MATERIALS, *ELECTROCHEMISTRY, *ENGINEERING, *ELECTRODES, *FUEL CELLS, OPTIMIZATION, VERIFICATION, AIR, CELLS, HIGH VELOCITY, CURRENT DENSITY, CARBON, ALLOYS, HYDROGEN, OXYGEN, TRANSPORT, PLATINUM, LOW DENSITY, FLOW, PRESSURIZATION, STACKING, ELECTROCATALYSTS.

Subject Categories : Physical Chemistry
      Electrochemical Energy Storage
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE