New materials for DMFC MEAs

Abstract

Abstract In recent years, the progress in the development of direct methanol fuel cells (DMFCs) for various applications has been enormous. It is probable that DMFC systems will soon be available as commercial products, especially in the low power range (<100 W). The materials currently used are, however, not optimized for the DMFC application. With this contribution we focus on the material aspects of the “active” components of the membrane electrode assembly (MEA). These components are the catalysts for the anode and cathode, the polymer membrane electrolyte and the diffusion layers. However, material issues regarding bipolar plates and other components of a stack are also discussed at the end of the review. After an introduction in which the basic concepts and processes of DMFCs are portrayed the main issues in DMFC development are discussed. Next, the specific demands that the materials must fulfil in DMFCs are presented. A discussion of the recent developments in membrane research and development follows, which is the crucial component regarding the goal to improve DMFC performance and fuel utilization. Therefore, we have devoted a considerable part of the chapter to this issue of new membrane materials. The catalysts and their reactivity are also an important issue in DMFC development. Both anode and cathode activities are crucial; we discuss mainly the systems that are already being used in MEAs. General considerations follow regarding electrode structure, catalyst utilization and porosity of the electrode. We also show in this contribution that besides the properties of the materials, the electrode structure also has a major influence on the processes in DMFCs.