Effect of turbostratic disorder on the staging phase diagram of lithium-intercalated graphitic carbon hosts.

The staging phase transitions which occur during the intercalation of lithium in graphitic carbons were probed by in situ x-ray-diffraction and electrochemical methods. Turbostratic disorder ~a random rotation or translation between adjacent graphene layers! in graphitic carbons ~heat treated above 2200°C! affects the formation of staged phases because lithium does not insert between randomly stacked graphene layers. We call these interlayer spaces ‘‘blocked galleries,’’ which frustrate the formation of the regular sequence of full and empty galleries, characteristic of staged phases. Higher staged phases, like stage 4 and stage 3, are eliminated as the probability P for turbostratic disorder increases in graphitic carbons made at temperatures near 2300 °C. Here, a staging phase diagram is developed in the P-x plane, where x is the lithium concentration in Li xC6 , which demonstrates how the turbostratic disorder affects staging.