Quaternized‐PAF Architecture Mediated Proton Channels to Enhance Ultra‐Robust Operation for 200°C Proton Exchange Membrane Fuel Cells

In optimizing the trade‐off between power density and phosphoric acid retention in PA‐doped polybenzimidazole (PA‐PBI) membrane for improving performance of high temperature proton exchange membrane fuel cells (HT‐PEMFCs), the self‐reinforcing network of interfacial interactions of the HT‐PEMs has to be deeply investigated. Herein, a breakthrough strategy employing a quaternary ammonium (QA)‐functionalized porous aromatic framework (QPAF‐225) to synergistically integrate with sulfonated poly[2,2’‐(p‐oxydiphenylene)‐5,5’‐bibenzimidazole] (SOPBI) to form the robust HT‐PEM is successfully developed. The ionic interactions between cationic QA moieties and anionic sulfonic acid groups can establish a self‐reinforcing proton‐conductive network, while the high‐density basic sites in QPAF‐225 acted as PA reservoirs can mitigate the leaking. When benchmarked against QA‐deficient PAF‐225‐10 (10% PAF‐225/SOPBI) and SOPBI, the QPAF‐225‐10 delivers a high proton conductivity (174 mS cm−1) and extremely high peak power density of 847 mW cm−2 under ultralow Pt/C loading (0.3 mg cm−2) at 200°C. Critically, such a membrane exhibits ultralow voltage decay rate (0.04 mV h−1, 904 h, 200°C) and high PA retention ability, coupled with mechanical robustness exceeding industrial durability thresholds. This work transcends conventional additives by exploiting PAF‐mediated proton channels and PA‐philic motifs, establishes a material paradigm for next‐generation HT‐PEMs that reconciles high‐power operation with long‐term stability in harsh electrochemical environments.