Free Volume and Oxygen Permeability in Polymers Related to Polymer Electrolyte Full Cells

摘要

Nafion and sulfonated poly(ether sulfone) SPES are used as the membrane in polymer electrolyte fuel cells (PEFC). Permeation of oxygen and hydrogen through the membrane reduces the efficiency of PEFC, so that understanding the mechanism of gas permeation in sulfonated polymers is of essential importance. Free volume holes in polymers play a crucial role in determining its gas permeability. So, free volume and oxygen permeability of Nafion membranes in many forms (H+, Na+, and K+) and SPES with different ionic exchange capacities have been investigated. Free volume quantified using the positron annihilation lifetime technique and oxygen permeability were measured as a function of temperature.