High temperature proton conducting organic-inorganic nanohybrids for polymer electrolyte membrane - Part II

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 100degreesC. If there is an alternative polymer membrane with high stability and sufficient protonic conductivity in the temperature range above 100degreesC, 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 250degreesC and to have protonic conductivities of approximately 10(-3) to 10(-2) S/cm from a room temperature to 140degreesC under a humidified condition. The current membrane is potentially useful in an intermediate temperature-operated advanced fuel cells system. (C) 2002 The Electrochemical Society.