Double-Layer Expanded Polytetrafluoroethylene Reinforced Membranes with Cerium Oxide Radical Scavengers for Highly Stable Proton Exchange Membrane Fuel Cells

As a key component of proton exchange membrane fuel cells (PEMFCs), the durability of the proton exchange membranes (PEMs) directly determines the service life of the PEMFCs. As state-of-the-art PEMs, perfluorosulfonic acid (PFSA) membranes suffer from critical mechanical and chemical degradation under actual working conditions. Considering this, we present a strategy to develop highly durable PEMs by intercalating double-layer expanded polytetrafluoroethylene (ePTFE) skeletons and doping CeO2 radical scavengers into the PFSA membranes. The results reveal that the double-layer ePTFE reinforced membranes (DR-Ms) have significantly improved mechanical properties, lower swelling rates, and superior dimensional stability compared to single-layer ePTFE reinforced membranes (SR-Ms). After the wet/dry cycle durability test, DR-Ms show a lower hydrogen crossover increase, reduced power performance attenuation, and smaller membrane impedance increase than SR-Ms. After the open-circuit voltage (OCV) durability test (ODT), DR-Ms exhibit better chemical durability behaviors (such as membrane thinning and OCV decay rates). Furthermore, the 0.5 wt % CeO2-doped DR-M (Ce-DR-M1) imparts a further improved chemical durability during the ODT compared with DR-Ms. In short, the developed Ce-DR-M1 with double-layer ePTFE skeletons and CeO2 radical scavengers is a promising candidate for advanced PEMs with high mechanical and chemical durability for PEMFC applications.