Conductivity and Water Uptake of Aromatic-Based Proton Exchange Membrane Electrolytes

Abstract

Water uptake and proton conductivity as a function of temperature were determined for three aromatic‐based, sulfonic acid‐bearing polymers, plus the perfluoroalkyl sulfonic acid Nafion® 117. Water uptake of submerged, equilibrated samples ranged from less than five water molecules per acid group for a high equivalent weight, sulfonated polyethersulfone to almost fifty waters per acid for a low equivalent weight, sulfonated polyetheretherketone. The most conductive aromatic‐based polymer, sulfonated polyphenylquinoxaline (S‐PPQ), had a room temperature conductivity of 9.8×10−3S/normalcm . about an order of magnitude less than that of a perfluoroalkyl sulfonic acid under identical conditions. The slope of the S‐PPQ Arrhenius conductivity plot was sufficiently steep that at 180°C, the proton conductivity, 1.3×10−1S/normalcm , was only a factor of two lower than that of Nafion under similar conditions. The lower conductivity of the aromatic‐based sulfonic acid polymers can be attributed to chain rigidity, lack of ion channels, and lower acidity. © 2000 The Electrochemical Society. All rights reserved.

High ionic exchange capacity polyphenylsulfone (SPPSU) and polyethersulfone (SPES) cross-linked by annealing treatment: Thermal stability, hydration level and mechanical properties

“…The aromatic structure can be functionalized and when ionomeric groups, like sulfonic acid, are inserted in the polymeric backbone, the macromolecule can be used as a polymer electrolyte membrane. Sulfonated polyphenylsulfone (SPPSU) and polyethersulfone (SPES) belong to the family of sulfonated aromatic polymers (SAP), well known compounds in the community of polymer electrolyte membrane fuel cells (PEMFCs) [2][3][4][5][6][7][8]. Famous exponents of this class are sulfonated polyetheretherketone (SPEEK), sulfonated polyetherketoneketone (SPEKK), and sulfonated polysulfone (SPSU).…”

Beneficial effect of carbon nanotubes on the performances of Nafion membranes in fuel cell applications

“…The first one consists in replacing Nafion® by alternative polymers, such as sulfonated polyetherketone [1,2], sulfonated polysulfone [3][4][5], sulfonated aromatic polyimide [6,7] and polybenzimidazole (PBI) doped by a strong acid, e.g., H 3 PO 4 and H 2 SO 4 [8][9][10]. PBI membranes are remarkable because they do not need to be humidified for exhibiting high ionic conductivity, which allows for operation at temperature higher than 100°C.…”

Direct spun aligned carbon nanotube web-reinforced proton exchange membranes for fuel cells

“…In general, the proton conductivity of all membranes was slightly higher at 90 °C than 75 °C ( Fig. 2c), which is typical Arrhenius behaviour of proton conduction, 17,18 with Nafion 212…”