Analysis of Transport Characteristics of Protons in Polymer Electrolyte Membranes in PEFC below Freezing Temperatures

The PEFC has been developed to achieve carbon neutralization and Sustainable Development Goals (SDGs) worldwide. One of the biggest problems in PEFC is the decrease in proton diffusivity in polymer electrolyte membranes (PEM) below freezing temperatures. In this study, ReaxFF simulations are used to reveal the transport characteristics of proton diffusion at various water content in such environment. The proton diffusion coefficient was calculated to evaluate the dependence of proton diffusion on water content in such environments. The number of proton hopping events and the number of rattling was analyzed to evaluate proton diffusion caused by Grotthuss mechanism. The radial distribution function (RDF) was also calculated to investigate structural differences at various water contents.