The Proton Transport Mechanism of Perfluorosulfonic Acid Membranes

An understanding of proton transport within perfluorosulfonic acid (PFSA) membranes is crucial to improve the efficiency of proton exchange membrane fuel cells. Using reactive molecular dynamics simulations, we have examined proton transport in two PFSA materials, Hyflon and the 3M membrane, at three different hydration levels. The interaction between the sulfonate group of the polymer side chains and the hydrated protons was found to have only a small influence on the proton transport dynamics. Instead, proton swapping between sulfonate groups is the primary transport mechanism for the proton transport within the pore. The larger water clusters and more flexible side chain of the 3M membrane allows for an enhancement of this swapping mechanism compared to Hyflon. Membranes that can enhance this mechanism may result in greater proton conductivity.