A polytetrafluoroethylene/quaternized polysulfone membrane for high temperature polymer electrolyte membrane fuel cells

A polytetrafluoroethylene (PTFE)/quaternized polysulfone (QNPSU) composite membrane has been fabricated for use in proton exchange membrane fuel cells (PEMFCs). The composite membrane is made by immobilizing a QNPSU solution into a hydrophobic porous PTFE membrane. The structure of the composite membrane is examined by SEM and EDX. The ionic conductivity of the PTFE/QNPSU membrane, at a relative humidity lower than 0.5% and a temperature of 180 °C, is greater than 0.3 S cm−1, when loaded with 400% H3PO4. A hydrogen fuel cell with this membrane operating at 2.0 atmosphere absolute (atma) pressure and 175 °C gives voltages >0.4 V at current densities of 1.0 A cm−2 using oxygen.

Research highlights▶ We used a porous polytetrafluoroethylene (PTFE) membrane as the mechanical supporting structure and the quaternized polysulfone (QNPSU) loaded with H3PO4 as proton conductor to fabricate the membrane. ▶ The PTFE/QNPSU/H3PO4 membrane conductivity was greater than 0.3 S cm−1 at a relative humidity lower than 0.5% and a temperature of 180 °C with a 400% H3PO4 doping level. ▶ A hydrogen fuel cell using this membrane with oxygen, at 2.0 atmosphere absolute (atma) pressure gave cell voltages >0.4 V at current densities of 1.0 A cm−2.