Development of MEAs Using Mesoporous Carbon Fibers as Cathode Carbon Supports

Mesoporous carbon fibers were synthesized and ball-milled into fine carbon particles to use as cathode carbon support. A critical issue of high ohmic overvoltage, previously found in mesoporous carbon related supports, was successfully reduced. Reducing carbon particle size was realized to be important in order to lower interparticle resistance and further to lower ohmic resistance. When cathodes were successfully prepared, low concentration overvoltage was found to a beneficial point of using mesoporous carbon based supports. Resulting low concentration overvoltage could not be explained by the difference in macro-porous structure of the cathode. Therefore, mesopores are expected to play an important role of the mass transfer, even though the exact mechanism is still under the study.