UC Merced

Fuel cells are electrochemical devices that convert chemical energy of fuel into electricity, with water and heat as reaction byproducts. They have many promising features like high power density, good fuel efficiency, and zero GHG emissions. All these features make fuel cells great potential to be a future replacement for the fossil fueled combustion engines. Water management and flooding phenomena however has been one of the most crucial performance limiting issues under high current density conditions in proton exchange membrane fuel cells. Various strategies have been developed to address this and it is continuing topic of research in the field.

In my study, I examined a fuel cell component known as the gas diffusion layer (GDL). The GDL is often treated with hydrophobic agent like PTFE, and often incorporated with an additional layer referred to as a microporous layer (MPL) for improving the cell performance through effective water management. Many studies have been published to investigate the effect of wetproofing and MPL. But there has not been any systematic study in the literature to directly quantify the effect of GDL wetproofing and MPL. Fuel cell performance, limiting current techniques, and material characterization tools were applied for this study. Adding PTFE wetproofing and a MPL increased gas diffusion resistance slightly and therefore did not have a significant adverse effect on cell performance under dry conditions. Under wet conditions, the PTFE wetproofing could delay, but not completely mitigate the liquid water flooding in the catalyst layer. On the other hand, adding the MPL allows for stable high current density operation under wet conditions.

To further investigate transport phenomena in a fuel cell, I performed a preliminary study on an alkaline exchange membrane fuel cell (AEMFC). The preliminary results indicate that the cell performance is sensitive to electrode structure and operating conditions, such as temperature and relative humidity. These results identify key research areas for my future study