Hydrocarbon‐Based Ionomer/PTFE‐Reinforced Composite Membrane Through Multibar Coating Technique for Durable Fuel Cells

Abstract For cost reduction and environmental‐friendly manufacturing, it is highly demanded to replace the current perfluorinated sulfonic acid‐based membrane in polymer electrolyte membrane fuel cells (PEMFCs) with inexpensive and readily available hydrocarbon‐based (HC) membranes. However, HC membranes suffer from profound dimensional changes caused by swelling and shrinking during operation, especially in automotive applications. These changes lead to severe mechanical degradation and shorten the service life of PEMFC. Herein, a multibar coating system is developed to manufacture HC/polytetrafluoroethylene (PTFE) composite membrane. This system facilitates capillary‐rise infiltration with the aid of an optimal amount of residual alcohol solvent on the PTFE. To address compatibility issues between PTFE and HC‐ionomer solutions, the effects of residual alcohol solvent on tuning the PTFE surface are investigated by controlling systemic parameters and performing diverse mechanical, optical, and electrochemical measurements. Based on its enhanced mechanical toughness (≈30.04%) and superior impregnation properties, the constructed HC/PTFE composite membrane exhibited more than seven‐fold improvement in mechanical durability under repeated accelerated wet–dry conditions compared with an unsupported pristine HC membrane while also mitigating performance loss (≈5.84%).