3-Triethylammonium propane sulfonate ionic liquids for Nafion-based composite membranes for PEM fuel cells.

The 3-triethylammonium propane sulfonic (TEA-PS⁺) cation associated with the anion tetrafluoroborate, hydrogen sulfate or trifluoromethanesulfonate leads to the formation of the new protic ionic liquids (ILs) 3-triethylammonium propane sulfonic acid tetrafluoroborate (TEA-PS·BF₄), 3-triethylammonium propane sulfonic acid hydrogen sulfate (TEA-PS·HSO₄) and 3-triethylammonium propane sulfonic acid trifluoromethanesulfonate (TEA-PS·CF₃SO₃), respectively. These ILs are used to produce Nafion/IL composite membranes with 2.5, 5 or 10 wt% of IL. The results show that the IL addition improves the thermal stability, hydrophilicity and conductivity. Experiments performed with the Nafion/IL membranes in a single proton exchange membrane fuel cell at 100 °C indicate that the membrane containing 5 wt% of TEA-PS·HSO₄ is the most efficient one producing an increase of the maximum current density of approximately 230% when compared to the pristine membrane. [ABSTRACT FROM AUTHOR]