关键词: 膜电极, Pt载量, 极化过电位, 电荷传输阻抗, 催化层结构

Abstract: Membrane electrode assemblies (MEAs) are the key component of proton exchange membrane fuel cell. For a long time, much attention has been paid to develop MEA technology. At present, the research, development and industrialization of fuel cell has entered a new era. More strict requirements for MEA, especially for the reduction of Pt loading with a challenging target of 0.125 mg·W^-1 have to be met. In this paper, the performance losses under low Pt loading are analyzed in terms of activation polarization, ohm polarization and mass-transfer polarization. It is proposed that research should be focused on the activity of the catalyst under the fuel cell operating voltage (0.6 V ~ 0.8 V)，and the reasonability of using charge-transfer resistance as the indicator of catalyst activity is discussed. In terms of optimization potential capacity, mass transfer polarization > activation polarization > ohm polarization. Residual performance loss associated with low cathode Pt loading can be mitigated by optimizing the catalytic layer structure, where oxygen flux through the ionomer film to the Pt surface should be minimized with high proton conduction.

Key words: membrane electrode assemblies, Pt loading, polarization over-potential, charge-transfer resistance, catalytic layer structure