Polyetheretherketone Membranes for Elevated Temperature PEMFCs

Abstract

Membrane electrode assemblies (MEAs) made from polyetheretherketone (PEEK) showed excellent fuel cell performance and thermal stability in the presence of substantial CO at elevated temperatures (i.e., 120°C) in proton exchange membrane fuel cells (PEMFCs). For example, the current from a MEA made from PEEK membrane at 0.6 V and 120°C was 0.50 A/cm 2 when run on pure hydrogen and 0.45 A/cm 2 when run on reformate (50% H 2 , 1300 ppm CO, and balance N 2 ). The current density from a MEA made from Nation at 0.6 V and 120°C was 0.61 A/cm 2 when run on pure hydrogen. The main difference between these two MEAs is that the ionic conductivity of the PEEK membrane at 120°C was 3.38 X 10 - 2 S/cm, which is approximately three times lower than Nation. Although it is not surprising that CO tolerance increases with increasing temperature, we are the first to show less than 10% drop in performance with 1300 ppm CO at 120°C. Even though Nafion membranes have higher conductivity, PEEK membranes lasted for 350 h thereby outlasting Nation membranes by seven to eight times.