Unveiling the effect of polytetrafluoroethylene (PTFE) content in catalyst layers for high-temperature proton exchange membrane fuel cells based on CsH5(PO4)2-doped polybenzimidazole membrane: Experimental and molecular dynamic study

The structural optimization of catalyst layers is essential for enhancing the performance and durability of high-temperature proton exchange membrane fuel cells based on CsH 5 (PO 4 ) 2 -doped polybenzimidazole membranes. In this work, catalyst layers with different polytetrafluoroethylene (PTFE) contents (10, 20, 30, and 40 wt%) are systematically investigated through experiments and molecular dynamics (MD) simulations to elucidate the correlation between electrode microstructure and cell performance. The membrane electrode assembly (MEA) with 30 wt% PTFE achieves the highest peak power density (1012 mW cm −2 under H 2 /O 2 condition and 728 mW cm −2 under H 2 /Air condition). At this optimal binder content, the catalyst layer forms a well-integrated porous structure with minor cracks, effective acid distribution, and a sufficient number of catalyst active sites. Both lower and higher PTFE contents are inappropriate and led to an inferior cell performance; an insufficient amount of PTFE resulted in acid flooding and poor structural cohesion, whereas an excessive amount of PTFE leads to blocked pores and covered catalyst sites. MD simulations further confirms that PTFE content significantly influences the phosphoric acid distribution near catalyst surfaces. Moreover, the MEA with 30 wt% PTFE exhibits excellent stability, showing a voltage degradation rate of only 6.67 μV h −1 during the 150-h durability test. • Systematic investigation of PTFE binder content (10–40 wt%) in HT-PEMFC CLs. • Combined experiments and MD simulations reveal PTFE content effects. • Inadequate or excess PTFE disrupts triple-phase boundary formation. • MEA with 30 wt% PTFE achieves 1012 mW cm −2 at 200 °C.