Structure and properties of deeply Li-doped polyacenic semiconductor (PAS)

As an anode material of lithium rechargeable battery, amorphous carbon materials have been studied extensively because of their high electrochemical performance. The polyacenic semiconductor (PAS) materials prepared from phenol resin at relatively low temperatures (500–1000°C) show a highly Li-doped state up to C2Li state without liberation of Li cluster. The Li storage mechanism as well as the large hysteresis observed in the voltage-capacity profile of the amorphous carbon materials are still the subjects of controversy. We review the proposed models of Li storage mechanism and present the results of our molecular orbital (MO) calculations. It will be shown that the nature of Li dopant is strongly dependent on the position of Li dopant. Possibility of the formation of small Li clusters is also discussed.