膜电极是质子交换膜燃料电池的核心组件，长期以来，在衣院士的指导下，我国高度重视膜电极技术的开发. 目前，燃料电池的研发和产业化进入了一个新的时代，对膜电极提出来更高的要求，特别是在降低铂载量方面，提出了0.125 mg·W^-1的挑战性指标. 本文从活化极化、欧姆极化和传质极化三个方面分析了低铂载量情况下电池性能下降的原因，提出应重点关注催化剂在燃料电池工作区间（0.6 V ~ 0.8 V)的催化活性，并讨论了用电荷传输阻抗作为催化剂活性指示符的合理性. 从优化潜力来说，传质极化优化>活化极化优化>欧姆极化优化. 催化层结构优化是实现低铂目标的关键，重点是解决离子聚合物（ionomer）传递质子和阻碍气体的矛盾.

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.