Effect of Different Binders on the Mass Transfer Performance of PEMFCs During Cold Start

The mass transfer ability within the catalytic layer determines the cold start behavior of proton exchange membrane fuel cells (PEMFCs). Ionomers within the catalytic layer serve as proton transfer mediators and create pore spaces. However, the impact of the ionomer’s side chain length on the transportation of protons and oxygen during cold start requires further investigation. In this work, this mass transfer phenomenon under different side chain length conditions was examined systematically using molecular dynamics (MD) methods. The results indicate that as to cold start mode, there is a gradual increase in oxygen molecules’ diffusivity with a decrease in the side chain’s length. Meanwhile, the diffusivity of hydrated hydrogen ions initially declines before experiencing a subsequent rise. In addition, the water molecules’ diffusivity shows volatilities. Meanwhile, the free volume first increases and then falls with the shortening of the side chain. This study provides a theoretical basis for the optimization design of PEMFCs catalytic layer.