Advanced design of electrospun nanofiber cathode catalyst layers for PEM fuel cells at low humidity

Electrospinning has emerged as a very promising preparation method of PEMFC cathode catalyst layers (CCLs) with high performance in the mass transport region due to their unique network structure for water transport and O2 accessibility. We will present the recent improvement strategies and humidity effect for electrospun nanofiber CCLs. Additionally, we will discuss the possible causes of their humidity-dependent performance losses. Thereby, the ionomer - carrier polymer interactions and local ionomer distribution play a critical role on the proton conductivity and accessibility of active Pt nanoparticles. Despite the high current densities achieved so far, more demanding PEMFC operating strategies are required to maintain the performance of nanofiber CCLs in a wide range of humidity.