Nanomaterials in Electrochemical Energy Conversion and Storage

A number of new approaches to creating more efficient devices for energy harvesting, storage, and conversion are based on the incorporation of nanostructured materials into electrochemical systems.  Such nanoelectrochemical energy systems hold particular promise for alternative transportation-related technologies, including improved batteries, dye sensitized solar cells, photoelectrochemical cells for solar hydrogen production, fuel cells, and electrochemical supercapacitors.  In this project, we are developing new tools and integrated measurement systems to characterize the chemical and physical transformations that occur at the nanoscale in electrochemical energy storage and conversion devices.

Transportation accounts for nearly two-thirds of U.S. domestic oil consumption, and is the single largest contributor to U.S. carbon dioxide emissions.  The U.S. imports about twice as much oil as it produces domestically.  Moving to an electrically powered transportation system that draws on sustainable energy supplies is expected to lower transportation costs, reduce greenhouse gas emissions, and help reduce the nation’s dependence on foreign oil.  Improved electrical energy storage is also paramount for widespread integration into the electrical grid of solar, wind, and other non-polluting, but intermittent, energy resources. 

In order to switch to cleaner energy technologies for transportation, new technologies must be developed to extract and store energy at densities that can compete with petroleum.  Incorporating nanostructured electrodes into electrochemical energy conversion and storage devices offers several advantages for a variety of transportation and other “green” energy infrastructure applications, including batteries, fuel cells, and so-called “supercapacitors.”  In each of these devices, nanostructured materials can be used to increase the surface area where the critical chemical reactions occur within the same volume and mass, thereby increasing the energy density, power density, electrical efficiency, and physical robustness of the system.  Such materials also have the potential to lower the manufacturing costs.

The fabrication and effective use of nanomaterials in electrochemical devices presents formidable challenges, however.  In particular, scientists do not yet fully understand the interfacial reactions and phase transformations that accompany charge transfer in electrochemical solutions.  Controlling these phenomena requires careful measurements and a fundamental knowledge of how nanoscale surface composition, structure, and defects affect these processes.

To address these challenges, we are building an integrated characterization system that combines the ability to examine electrochemical properties within an inert atmosphere with surface and bulk spectroscopic and charge transport measurements performed in ultra high vacuum.  This system will be used to develop and characterize a range of electrochemical energy conversion and storage devices, including batteries, fuel cell electrocatalysts, electrochemical capacitors, and photoelectrochemical cells for hydrolysis.  These measurements will provide the key knowledge needed to improve the efficiency and performance of such devices.