The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. David S. Mebane to work with Dr. Joachim Maier at Max Planck Institute in Stuttgart, Germany.
The focus of the project is developing a phenomenological model to explain storage phenomena seen in nano-sized materials for negative electrodes in lithium ion batteries. In particular, the work focuses on the storage capabilities seen in transition metal oxides such as RuO2 and CoO. Upon cycling with Li+, these materials form composites comprised of Li2O and nanosized metallic particles. The work expands upon the theory, put forward by Jamnik and Maier, that storage in these nanocomposites is primarily a space-charge phenomenon, building it into a continuum framework suitable for comparison with experiment. The phenomenology used in the continuum framework addresses not only the effect of charge separation, but that of surface tension and chemical interaction on the relevant electrochemical potentials. Such a treatment of the change in electrochemical potentials with respect to the bulk leads to the energetics of defect formation, transport and reactivity in confined spaces. Key to the success of this effort is establishing connections between theoretical work and experiment. Collaborating with experimentalists in the Maier group, unique test cells are designed, and the experimental results compared with predictions of the continuum model. In addition, where applicable, connections with theorists working in first principles simulation, such as quantum chemical and molecular dynamics modeling, are made in order to reduce the number of unknown constants in the continuum framework and to understand the phenomenology on a more fundamental level.
