Ionic Conducting Thermostable Polymers: Properties and Applications to Membranes for Fuel Cells
The Proton Exchange Membrane Fuel cells (PEMFC) are developed in private or public laboratories for different applications such as vehicles or portable electricity sources. The Direct Methanol Fuel Cells (DMFC) use methanol instead dof hydrogen. If the performances of DMFC in term of power density are lower than the hydrogen fed fuel cells, the use of a liquid fuel such as methanol is an important advantage. For both fuel cells, the performances of the polymer proton exchange membranes condition the performances of the cells. In order to improve the performances, different other components are concerned such as the catalysts, and the Electrode membrane Assembly (EMA). This paper is focused on the polymer ion exchange membranes and the results obtained in DMFC.
Membranes able to work at high temperature, with low methanol crossover and good conductivity are essential. For that purpose, thermostable polymers are used and hybrid membranes are developed. The structure and some properties of these membranes will be described as well as the improvement in the field.
The results on two programs on DMFC are described: a European program called NEMECEL and an other program called OPTIMET. The program OPTIMET (supported by the “National PACO Network”) is related to the optimisation of a direct methanol fuel cell (DMFC). This program, which associates four partners, has for objectives the optimisation of the different components and the conception of a DMFC stack in order to increase the performances. Different components are concerned such as the catalysts, the membranes and the MEA. The final objective is the design and building of a stack of specific power of 80 W/Kg.