The development of PTFE/Nafion/TEOS membranes for application in moderate and high temperature proton exchange membrane fuel cells

PTFE/Nafion (PN) and PTFE/Nafion/TEOS (PNS) membranes were fabricated for the application of moderate and high temperature proton exchange membrane fuel cells (PEMFCs), respectively. Membrane electrode assemblies (MEAs) were fabricated by PTFE/Nafion (and PTFE/Nafion/TEOS) membranes with commercially available low and high temperature gas diffusion electrodes (GDEs). The effects of relative humidity, operation temperature, and back pressure on the performance and durability test of the as-prepared MEAs were investigated. Incorporating TEOS into a PNS membrane and adding another layer of carbon onto a GDE would result in low membrane conductivity and low fuel cell performance respectively. However, in this work it is shown that HT-PNS MEAs demonstrate a higher performance than LT-PN MEAs in severe conditions – high temperature (118 °C) and low humidity (25% RH). The TEOS and additional carbon layer function as water retaining agents which are especially important for high temperature and low humidity conditions. The HT-PNS MEA showed good stability in a 50 h fuel cell test at high temperature, moderate relative humidity (50% RH) and back pressure of 14.7 psi.