DEVELOPMENT OF SMALL POLYMER ELECTROLYTE FUEL-CELL STACKS

The results on the research and development of small polymer electroly te fuel cell stacks, including the assembly of single cell, 6-cell and 21-cell modules, an described. The important characteristics of the s ystems are: (i) membrane and electrode assemblies were made with Nafio n(R) 115 and 117 membranes and particularly low catalyst loading elect rodes presenting a geometric area of 20 cm(2) and a catalyst loading o f 0.4 mg Pt/cm(2); (ii) bipolar plates were fabricated using a nonporo us graphite material in which a series/parallel flow field was machine d out; (iii) external distribution of gases to the cells was done usin g parallel manifolding; (iv) cooling systems were tested employing wat er/air cooling plates distributed every three cells throughout the sta ck; (v) the reactant gases were externally humidified using temperatur e controlled humidification bottles. Testing of the stacks was conduct ed in a specially designed test station employing nonpressurized H-2/O -2 reactants and measuring the individual and the overall cell voltage vs. current under several conditions for the overall system operation . (C) 1998 Elsevier Science S.A.