Anodic performance of vapor-derived carbon filaments in lithium-ion secondary battery

The electrochemical characteristics of vapor-derived carbon filaments of diameter 0.1 μm were studied by charge-discharge testing of a lithium-ion secondary cell with a lithium metal electrode. After activation, followed by either nitridation or reduction in hydrogen, vapor-derived carbon filaments show high reversible charge and discharge capacities. An ordered structure and a large pore size are favorable for a high capacity, as shown by comparison of vapor-derived and pitch-derived carbons. The combination of a high specific surface area and a large amount of oxygen-containing surface functional groups results in a high irreversible capacity. To improve the anodic performance, it is important to control the surface microstructure by decreasing the surface oxygen content by nitridation or reduction in H₂, while maintaining order in the crystallographic structure with surface mesoporosity.