Electronic states in heavily Li-doped graphite nanoclusters

Negative ion states for Li atoms are found in graphite nanoclusters heavily doped with lithium using a semiempirical calculational method. These calculations identify a quasi-stable site for a negative Li ion near the terminated hydrogen atoms, and this site becomes very stable in the presence of the Coulomb interaction between Li ions. The total charge transfer from Li ions to the graphite clusters does not depend on the number of Li atoms per cluster but rather on the relative geometries of the Li atoms on the cluster. The relationship of these findings to the findings in the 7Li nuclear magnetic resonance experiments and to the performance of Li secondary batteries is discussed.