Durability and stability test of proton exchange membrane fuel cells prepared from polybenzimidazole/poly(tetrafluoro ethylene) composite membrane

摘要

It has been reported that a thin polybenzimidazole (PBI)/poly(tetrafluoro ethylene) (PTFE) composite membrane (thickness 25-30 μm) can be prepared by impregnating a thin porous PTFE (thickness 15-20 μm) in a PBI/N, N'-dimethyl actamide (DMAc) solution. In this paper, a 400h life test of a fuel cell prepared from PBI/PTFE composite membrane was carried out at 160℃ with a current density i = 200 mA cm~(-2). During long time test, the i-V curve and AC-impedance measurements were conducted every 12 h. The experiment data showed a 240h period of activation. After 240h the cell voltage started to decay. AC-impedance measurements showed internal resistance (R_s) and charge transfer resistance (R_c) decreased in the initial 240h life test and then R_s remained almost constant and R_c increased after 240 h. The decay of fuel cell performance can be attributed to the migration of phosphoric acid out from membrane leading to the delamination between membrane and electrodes.