High temperature proton conducting organic/inorganic nanohybrids for polymer electrolyte membrane

Polymer electrolyte membrane fuel cells (PEMFCs) have been recently investigated extensively as a key technology to solve a global energy and environmental problem by their higher energy conversion efficiency compared to internal combustion engines. The electrolyte membrane is a basic element in PEMFC, however, the polymer electrolyte membrane, typically such as Nafion, usually suffers from degradation at higher temperature, resulting in narrow operational temperature windows below 100°C. If there is an alternative polymer membrane with high stability and sufficient protonic conductivity in the temperature range above 100°C, an intermediate temperature operated PEMFC can be realized which can potentially overcome major problems in the current system such as CO poisoning on the Pt surfaces: large amount of Pt metals at both electrodes and heat management. Additionally, direct methanol fuel cells (DMFCs) can be feasible at intermediate temperature operation. In this work, sol-gel processes have been used to synthesize a new family of polymer electrolyte membrane consisting of organic/inorganic nanohybrid macromolecules. The flexible, homogeneous, and large-sized hybrid polymer membrane has been found to be thermally stable up to 250°C and to have protonic conductivities of approximately 10^-3 to 10^-2 S/cm from a room temperature to 140°C under a humidifi condition. The current membrane is potentially useful in an intermediate temperature-operated advanced fuel cells system.