CHARGE-DISCHARGE CHARACTERISTICS OF MESOPHASE-PITCH-BASED CARBON-FIBERS FOR LITHIUM CELLS

Mesophase-pitch-based carbon fibers were heat-treated at high temperatures (2600 or 2800-degrees-C) and examined as anodes for lithium secondary batteries. Four types of carbon fibers were used whose cross-sectional views are: a radial texture with wedge (type A), a radial texture with fine zigzag layers (type B), a double texture (type C), and a concentric texture (type D). Lithium could not be deintercalated after the first lithium intercalation in the type A carbon fiber. The structure of the type A fiber was destroyed during lithium intercalation. The other three types of carbon fibers showed good rechargeability on the first cycle, but demonstrated different behavior after 3 () cycles. The highest lithium intercalation and deintercalation capacity was observed for the radially oriented carbon fiber (type B). The x-ray results showed a reversible change in the lattice along the c-axis during the intercalation and deintercalation cycle.