Influence of PTFE content on structural parameters of microporous layer and its performance in PEMFCs

The gas diffusion layer (GDL) is the water management center of proton exchange membrane fuel cells (PEMFCs), and the composition and structural parameters of this microporous layer (MPL) seriously affect the performance of fuel cells. Herein, a three-dimensional model of MPL structure, with different PTFE contents, is established based on the close-packed structure model, and the concept of critical pigment volume concentration (CPVC) during the coating process is introduced to elucidate what. The porosity of MPL with different PTFE contents is calculated by using the di-n-butyl phthalate (DBP) absorption number of Vulcan XC-72 and compared with the experimental values. The influence of PTFE content and structural parameters on the performance of a single cell is analyzed based on the porosity, surface morphology, water and gas permeabilities, hydrophilicity, hydrophobicity and surface resistivity of MPLs with different PTFE contents. The optimal PTFE content in MPL is determined to be 20 - 30%, and the maximum power density of a single cell is achieved to be 1.55 W/cm 2 .