Correlating Humidity Dependent Ionically Conductive Surface Area With Transport Phenomena In Proton Exchange Membranes

Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

Nanotechnology in Fuel Cells

Nanotechnology in Fuel Cells focuses on the use of nanotechnology in macroscopic and nanosized fuel cells to enhance their performance and lifespan. The book covers the fundamental design concepts and promising applications of nanotechnology-enhanced fuel cells and their advantages over traditional fuel cells in portable devices, including longer shelf life and lower cost. In the case of proton-exchange membrane fuel cells (PEMFCs), nano-membranes could provide 100 times higher conductivity of hydrogen ions in low humidity conditions than traditional membranes. For hydrogen fuel cell, nanocatalysts (Pt hybrid nanoparticles) could provide 12 times higher catalytic activity. This is an important reference source for materials scientists and engineers who are looking to understand how nanotechnology is being used to create more efficient macro- and nanosized fuel cells. - Outlines how fuel cells can be nanoengineered to enhance their performance and lifespan - Covers a variety of fuel cell types, including proton-exchange membrane fuel cells and hydrogen-based fuel cells - Assesses the major challenges of nanoengineering fuel cells at an industrial scale

Fast Ionic Conductors and Solid-Solid Interfaces Designed for Next Generation Solid-State Batteries