Anthracite as a candidate for lithium ion battery anode

Four kinds of anthracites from different regions were investigated as anodic materials of Li ion secondary battery by varying their calcination temperatures. Hon-gye anthracite calcined at 1000–1150 °C showed a high reversible capacity at low potential region of 0–0.12 V, which is typical with hard carbon. The highest capacity of 370 mAh/g was obtained with the Hon-gye among anthracites calcined at 1100 °C. The graphitization started with the anthracite above 1600 °C to provide capacity at ca. 0.2 V which reflects the intercalation of graphitic carbon. The anthracite calcined at 1000–1150 °C was indicated to carry the largest d002 and smallest Lc(002). And TEM observation showed micropores among the graphite clusters. The large capacity of the anthracite as hard carbon is ascribed to its many micropores among the smallest graphite units which can accommodate highly reduced lithium ions.