The effect of large negative potential excursions on the behavior of the lithiated carbon electrode is investigated by using a single-fiber electrode made from partially graphitic carbon. The micro-fiber technique allows one to isolate the properties intrinsic to the lithiation process, and the results are not complicated by the influence of binders, electronically conductive additives, current collectors, or other components necessary for the fabrication of porous carbon electrodes. The results indicate that the electrode can tolerate moderately negative potentials because the lithium insertion process is facile relative to that of Lithium deposition. For sufficiently negative potentials, however, lithium deposition occurs, an event that is exacerbated by increasing the lithium content within the carbon.