Development of an in-situ Sensing Technique of a Porous Electrode Formation Process

Abstract

A measurement system of the high-frequency resistance (HFR) and drying surface displacement of catalyst inks (slurries) under the drying process, which is to fabricate catalyst layer of polymer electrolyte fuel cells, was constructed and the measurement of the catalyst inks with the different ionomer to carbon (I/C) ratio were demonstrated. A self-made four-terminal micro-electrodes chip was fabricated and used for the HFR measurement. The drying surface displacement measurement was also conducted at the same time by using a laser displacement meter. The catalyst ink with lower I/C showed larger resistance at the beginning of the drying because proton concentration in the ink is low. The lower I/C inks also showed drastic resistance drop at the earlier time. Both the resistance decrease and film thickness decrease of the higher I/C ink occurred at the same time. This result indicates that I/C ratio affect the stability of the catalyst ink.