Polybenzimidazole/poly(tetrafluoro ethylene) composite membranes for high temperature proton exchange membrane fuel cells

A porous poly(tetrafluoro ethylene) (PTFE) thin film (thickness 16 ± 2 μm) is used as a supporting material for polybenzimidazole (PBI) to prepare the PBI/PTFE composite membrane (thickness 38 ± 2 μm). The perfluorosulfonic acid resin (Nafion) is used as a coupling agent at the interface between PTFE and PBI to improve the bonding between PBI and PTFE. The composite membrane, after doping with phosphoric acid, is used to prepare membrane electrode assemblies (MEAs). A 450 h continuous fuel cell life test at 160 °C with a fixed current density i = 200 mA cm−2 and a 20 cycles cell on/off test, in which the fuel cell is operated at 160 °C with i = 200 mA cm−2 for 12 h and then switched off at room temperature in an ambient environment for 12 h per cycle, are performed. Both tests show good fuel cell performances.