Enhanced properties of Nafion nanofibrous proton exchange membranes by altering the electrospinning solvents

Nanofibrous proton exchange membranes (PEMs) play an important role in improving the performance of the fuel cells. In this paper, two kinds of Nafion nanofibrous PEMs, Nafion-E/W and Nafion-DMF, were fabricated respectively by using ethanol/water (E/W) and N, N-dimethylformamide (DMF) as the solvent and their properties, such as the morphologies, water uptake, area swelling, ion exchange capabilities, conductivities, and mechanical properties were examined. Nafion-E/W nanofibers showed a thick diameter of 6,089 nm and Nafion-DMF nanofibers a thin diameter of 410 nm. Then the two Nafion nanofibers were annealed to provide the PEMs. Compared with Nafion 117 membranes and Nafion-DMF PEMs, Nafion-E/W PEMs showed the greatest water uptake and area swelling of respectively 59.75 % and 30.31 % and the conductivity increased to 0.1405 S/cm, more than twice as much as Nafion 117 membranes, but the broken stress decreased to 5.49 MPa, nearly half of Nafion 117 membranes. Nafion-DMF PEMs showed the lowest water uptake, area swelling, and conductivity of 22.67 %, 10.75 %, and 0.0410 S/cm, and the broken stress reached 14.20 MPa, greater than 11.0 MPa of Nafion 117 membranes. The obtained experimental results are instructive to improve the properties of Nafion PEMs.