分会场

燃料电池发动机

摘要

O2 transport phenomena in various phases in the membrane electrode assembly (MEA), including liquid water, bulk membrane and thin ionomer film on a Pt surface, are investigated using all-atom molecular dynamics (MD) simulations. The results show that O2 transport route is not in the water domain interior of a bulk membrane due to low O2 solubility in liquid water and is affected by water contents: at low water content, O2 molecules are mostly in the small cavities of bulk membrane and thus have a low diffusivity due to restriction of the small cavities, while at high water content they shift to the large interfacial areas between PFSA frameworks and water clusters where the O2 diffusion barrier is low. In the ionomer film on the Pt surface, O2 transport route varies in different regions: in Region I where a dense region with tightly arranged perfluosulfonic acid (PFSA) chains is present close to Pt surface, O2 tends to permeate through the water sites; in Region II which is in the middle of the ionomer film, the O2 transport property is similar to that in the bulk membrane; and in Region III that is a transition region from ionomer to gas, O2 can easily permeate because of the fewer PFSA and water molecules.

关键词

Proton exchange membrane fuel cell;O2 transport;Water;Membrane;Ionomer film;Molecular dynamics simulation

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