Nature of Proton Transport in Membranes for Fuel Cell Applications

Development of polymer electrolyte fuel cells (PEFCs) is actively ongoing nowadays because of their potential applications in portable and stationary systems. Polymer electrolyte membranes (PEMs) are important component of PEFC, whose role is to facilitate proton conduction and to separate the anode and the cathode. In the present contribution, we report results of first-principles molecular dynamics (FPMD) simulations carried out for various types of hydrocarbon membranes for fuel cell applications with an emphasis on how molecular structure of membranes affect the transport property of proton. Especially, we applied FPMD to sulfonated poly phenoxy benzoyl phenylene (SPPBP) and sulfonated (arylene ether ether nitrile) (m-SPAEEN). The results of FPMD show that various hydrophilic functional groups, such as the carbonyl group, affect the nature of proton transport in the hydrocarbon membranes. Details on the proton transport mechanism are discussed.