Scanning probe imaging of surface ion conductance in an anion exchange membrane

作者：He Qinggang^*; Ren Xiaoming

来源：Journal of Power Sources, 2012, 220: 373-376.

DOI：10.1016/j.jpowsour.2012.07.039

• Anion exchange membrane
• Current sensing SPM
• Ionic conductivity
• Fuel cells

The goal of this study was to investigate surface ion conductance variation in an anion-exchange membrane (AEM) using current-sensing scanning probe microscopy. No direct correlation was found between the membrane surface topography and local ion conductance. Smaller and larger conducting areas associated with ion channels and ionic clusters were identified in images of membrane surface ion conductance. Both the size of ion channels and the density of ionic clusters tended to increase significantly at higher relative humidity (RH) conditions. The ionic conductance of the AEM was one order of magnitude lower than its proton-exchange counterpart (Nafion (R)) at 100% relative humidity. This decrease may be due to the rate-limiting properties of the studied AEM, such as lower mobility of anions (HCO3- and OH-), smaller size of ionic channels, lower density of ionic clusters, and lower capability for water uptake as compared to Nafion (R) 212. Nevertheless, the ionic conductance was found robe higher on the AEM when the RH was lower than 45%. These results have direct implications for the application of the AEM in fuel cells without humidification systems. Published by Elsevier B.V.

• 出版日期2012-12-15