The MEA performance using triazole membrane depending on hot pressing condition in high temperature PEMFC

Abstract

The triazole has three nitrogens in the ring and then having high proton conductivity with phosphoric acid. In this study, we need triazole membranes as electrolyte of high temperature PEMFC. The triazole membrane and elecrodes (anode and cathode) was doped the phosphoric acid and the MEAs were prepared by hot pressing process. . In previous studies, using triazole membranes doping phosphoric acid, the MEA was prepared by sandwiching the membrane between the anode and cathode electrodes at 140 ℃ and 2 MPa for 2 min [1,2]. To determine if this MEA fabrication method is suitable for our membranes, we compared the performance of MEA by varying the temperature and pressure of the hot press. As a result, the highest performance was obtained when hot pressing was conducted at 140 ℃ and 2 MPa for 2 min. At the first Fig., the ohmic resistance (R/ohm) increased depending on temperature increasing due to leaching phosphoric acid at membrane. However, the charge transfer resistance (R/ct) was the lowest at 140 ℃. The proton transport in electrodes is depending on amount and distribution of phosphoric acid. Although doping phosphoric acid in electrode, the proton conductivity of electrodes was low at low hot press temperature because of phosphoric acid lack. At high temperature, as too much phosphoric acid moved from membrane to electrode, the charge transfer resistance increased due to phosphate poison. When changing the pressure, the phosphoric acid was lack at low pressure and the phosphate poison occurred mostly at high pressure. Therefore, the best hot pressing condition of triazole membrane is at 140 ℃ and 2 MPa for 2 min.