There is a need to develop advanced battery materials that provide higher energies than are available at present. Salts of the ferrate anion (FeO4) could serve this purpose because of the 3-electron transfer that occurs in these materials. To date, however, applications of ferrates are limited by chemical instability and incomplete utilization of the 3-electron transfer. In earlier studies, we have developed standard procedures for ferrate synthesis and determination of ferrate purity. Studies of ferrate instability in various electrolytes have been initiated and will continue during this project. The focus of this project is on improving the stability of various ferrate salts by coating them with thin films of nanoparticulate oxides, using techniques that have been successfully applied to improve the recharge characteristics of lithium-based cathode materials in collaboration with Argonne National Laboratory. Selected properties of coated ferrate salts used as cathodes will be measured, and their electrochemical behavior versus zinc and lithium anodes will be evaluated. Researchers at both Argonne National Laboratory and Rayovac Corp. will assist with the required electrochemical characterization.
Presently available batteries are limited in terms of both the energy that they can store, and the power that they can deliver to electronic devices. Highly oxidized iron materials, called ferrates, offer the possibility of improving battery design and performance. Studies to date, however, indicate that ferrates are not stable during long-term storage, and the amount of energy that they deliver in practice is significantly less than the theoretical limit. In this project we will attempt to improve the stability of ferrate materials by applying extremely thin coatings of nanoparticulate oxides to control the interaction with other battery materials that compromise ferrate integrity and performance. Successful completion of this project could lead to production of rechargeable batteries that deliver significantly more energy and power than present battery designs. The Approaches to Combat Terrorism Program in the Directorate for Mathematics and Physical Sciences supports new concepts in basic research and workforce development with the potential to contribute to national security.
