リン酸型燃料電池用電極の特性におよぼす触媒・PTFE粒子の分散・凝集状態の効果

抄録

In order to optimize the preparation condition of electrodes for phosphoric acid fuel cell (PAFC), we studied effects of dispersion and flocculation of particles (catalyst and PTFE) on the performance of electrodes. The average diameter and ζ potential of particles in pure water, anionic or nonionic surfactant solution were measured. Structures (poresize distribution, specific surface areas, FE-SEM images and wettability with phosphoric acid) and performances (1-V characteristic and endurance test) of electrodes prepared from these dispersions were evaluated. It was found that particles of catalyst and PTFE flocculate selectively each other (heteroflocculation) under the condition of flocculation (pH˂3) because of the opposite polarity of ζ potentials, when particles were dispersed in pure water or anionic surfactant solution. Both of electrodes prepared from dispersions in pure water and anionic surfactant solution have high output and long life as a PAFC cathode owing to a large effective reaction area (three phase boundary) because particles of catalyst and PTFE were distributed homogeneous in these electrodes. We succeeded in preparing high performance PAFC cathode from concentrated dispersion with particles with the system of anionic surfactant solution. This technology is industrially useful, because both the size of equipment and the time for filtration can be reduced.