The impact of different side chain ionomer on membrane electrode assembly performance and durability

The structural engineering of catalyst layers (CLs) offers a promising route to the commercialization of proton exchange membrane fuel cells (PEMFCs). It remains a challenging research topic by exploring the effect of different side chain ionomer on the structure of the catalyst layer. An in-depth analysis of the ionomer dispersion behavior in the catalyst ink is key to achieving optimal CL structure. In this work, the effect of ionomer side chain structure on cluster dispersion in catalyst ink and CL microstructure is investigated to reveal the correlation between catalyst ink, CL microstructure, and performance. When short-side chain (SSC) ionomers are used, the particle size distribution of clusters is uniform, the ionomer film on the surface of clusters is thinner, a homogeneous and continuous ionomer network is obtained, and the surface cracks on the CL are smaller and less. Therefore, the SSC membrane electrode assembly (MEA) has better proton conduction ability and lower mass transport resistance. Meanwhile, SSC-MEA has better voltage stability and less voltage degradation at high current density. For complex fuel cell structures, SSC ionomers are preferably selected as proton conductors and binders for the CL to optimize the three-phase interface structure, which can provide satisfactory fuel cell performance.