Buffer Electrolytes for Fuel Cells

Abstract

SULPHURIC acid, phosphoric acid and concentrated caustic solutions are the electrolytes most frequently used in the development of fuel cells, but they have disadvantages which justify the investigation of substitutes. The chief disadvantage of caustic electrolytes is their inability to reject carbon dioxide when a carbonaceous fuel is completely oxidized. Considering electrolyte invariance and ionic concentration polarization only, Williams and Gregory¹ recommend strong acid electrolytes for low temperature fuel cells. Acids, however, present a severe corrosion problem. Thus, fuel cells using acid electrolytes require noble metal catalysts, not only for catalytic activity, but also to withstand corrosion. The electrode supports must also either be a noble metal or a costly non-noble corrosion resistant metal such as tantalum. Cairns and MacDonald² have shown the feasibility of highly soluble carbonates as invariant electrolytes for fuel cells, although temperatures ranging from 130° to 200° C appear to be necessary. This communication shows that other choices of electrolyte are possible which may eliminate some of these problems.