Carbon fibers brominated by electrochemical intercalation

Bromine was intercalated in pitch-based carbon fibers (Thornel P-100 of Amoco) by either exposure to Br₂ or anodic oxidation (i.e., electrochemical intercalation). The former method resulted in fibers that exhibited in-plane disorder at room temperature and in-plane melting at 271 K, whereas the latter method resulted in fibers that exhibited in-plane superlattice order at room temperature and in-plane melting at 373 K. Compared to fibers prepared by the former method, fibers prepared by the latter method exhibited more homogeneous intercalation, a more uniform chemical state of the intercalated bromine, a higher electron transfer from bromine to carbon, a lower bromine concentration, a lower electrical conductivity, enhanced oxidation resistance, and an increased activation energy for oxidation. Highly oriented pyrolytic graphite did not undergo electrochemical intercalation under the same conditions as the fibers.