Mass transfer layer for liquid fuel cells

Performance of a new type of mass transfer layer (MTL) compared to a commercial material has been shown in single fuel cell testing. GRAFCELL® natural graphite MTL is used as a cathode diffusion media along with carbon cloth. Its chemically modified permeable structure is diffusion limited at high current densities, independent of temperature, while perforated structure provides temperature dependent performance increases. The impact of open area variation in perforated mass transfer layer (PMTL) is demonstrated at high current densities and shows advantages over commercial material at room temperature operation. Performance reaches about 25 mW cm−2 at room temperature testing with maximum current density around 250 mA cm−2. Better performance is attributed to large openings for liquid transfer with PMTL compare to ELAT. Being able to design perforations on expanded graphite material may also play role in developing passive fuel supply systems for future liquid fuel power sources.