| AVS 60th International Symposium and Exhibition | |
| Energy Frontiers Focus Topic | Tuesday Sessions |
| Session EN-TuP |
| Session: | Energy Frontiers Poster Session |
| Presenter: | R. Whitcomb, Rutgers Department of Physics and Astronomy Summer REU Program |
| Authors: | R. Whitcomb, Rutgers Department of Physics and Astronomy Summer REU Program R. Thorpe, Rutgers, The State University of New Jersey S. Rangan, Rutgers, The State University of New Jersey R.A. Bartynski, Rutgers, The State University of New Jersey |
| Correspondent: | Click to Email |
For the use of promising new technologies such as electric cars and smart power grids to become more widespread, batteries must be developed with the ability to store larger amounts of energy. Increases in energy density are often accomplished by substituting different compounds into already successful commercial battery architectures. As one of the most common types of portable power cells, conventional lithium ion batteries rely upon intercalation to store charge in the cathode:
Li+ + e- + CoO2 --> LiCoO2
This process can be improved by replacing lithium cobalt oxide with a conversion reaction material, whose structure and composition are instead chemically altered by lithiation. In particular, a cathode composed of FeF2 can react with lithium ions to produce metallic iron, storing an additional electron per formula unit:1
2Li+ + 2e- + FeF2 --> 2LiF + Fe
However, the mechanism by which this reaction progresses is not well understood, so it is important to investigate the chemical phase and morphological changes caused by the lithiation process in a model system. This has been accomplished by working with well-characterized samples outside of the electrolytic environment of a typical battery, thereby isolating the fundamental properties of the reacting materials. My poster describes the spectroscopic analysis of epitaxial iron (II) fluoride (110) thin films in ultrahigh vacuum, before and after a series of lithium exposures. Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS) was used to determine the chemical concentrations of the material as a function of depth in the film. Evidence supports a uniform reaction front progression downwards from the surface of the film, but with the presence of a barrier to full conversion of the fluoride. Funding for this project was provided by the National Science Foundation grant PHY-1263280.
1 Rangan, S.; Thorpe, R.; Bartynski, R. A.; Sina, M.; Cosandey, F.; Celik, O.; Mastrogiovanni, D. D. T. J. Phys. Chem. C 2012, 116, 10498-10503.