Cathode structure optimization for air-breathing DMFC by application of pore-forming agents

Abstract

The cathode catalyst layer in an air-breathing, direct methanol fuel cell (DMFC) has been improved by addition of pore-forming materials, such as ammonium carbonate and ammonium hydrocarbonate. These construct an effective electrode pore structure. During fabrication of the membrane electrode assembly (MEA), these pore-formers decompose, increase the BET surface area of the electrodes, and form additional porosity. Ammonium carbonate predominantly produces macropores, while ammonium hydrocarbonate is effective for mesopores. This results in an increase in electrochemical active area and catalyst utilization. The higher open-circuit voltage with MEAs prepared with pore-forming material indicates improved air transfer through the cathode. The power density is increased by 30-40% with the employment of the pore-forming materials. (C) 2007 Elsevier B.V. All rights reserved.