No abstract

Disordered carbons obtained by pyrolyzing organic solids at T ≤ 700 °C retain substantial residual hydrogen and exhibit surprisingly large capacities for Li uptake in electrochemical cells. Using semiempirical computer simulations, we show that the high capacity is partially attributable to Li binding on H-terminated edges of hexagonal carbon fragments, with local geometries analogous to the stable isomer of the organolithium molecule C2H2Li2. These results can be tested experimentally by vibrational spectroscopy and have implications for further developments in Li-ion rechargeable battery technology.

The vibrational density of states of single-wall carbon nanotubes (SWNT) was obtained from inelastic neutron scattering data from 0 to 225 meV. The spectrum is similar to that of graphite above 40 meV, while intratube features are clearly observed at 22 and 36 meV. An unusual energy dependence below 10 meV is assigned to contributions from intertube modes in the 2D triangular lattice of SWNT bundles, and from intertube coupling to intratube excitations. Good agreement between experiment and a calculated density of states for the SWNT lattice is found over the entire energy range.