ABSTRACT
As a representative of the electrochemical polymer electrolyte membranes, the proton exchange membrane (PEM) has been developed extensively as both a separator and an electrolyte in the operating fuel cell. In order to realize the potential of fuel cells, there is a need for smart and rational design of novel electrolyte membrane materials based on a fundamental understanding of membrane morphology, proton and mass transfer, and chemical and mechanical properties. However, additional advancements will still be necessary to meet aggressive operating conditions of higher temperatures and/or lower humidities, as well as longer operating longevity demanded in both automotive and stationary applications. The current PEM fuel cell utilizes peruorosulfonic acid (PFSA) polymer membranes, for example, Na–on®, as electrolyte that is limited to low-temperature and high methanol crossover. The state-of-the-art membrane research is focused on developing electrolyte materials that provide good conductivity in the absence of water. Hybrid/composite membranes exhibit the capability of both reinforcement of a thin membrane to provide mechanical durability and improvement of water retention to promote proton transport.
