ANODE PROPERTIES AND DIFFUSION-COEFFICIENT OF LITHIUM OF PITCH-BASED CARBON POWDER

Coal pitch based carbon powder, which was prepared at 1400 degrees C, was tested as the anode material of lithium secondary batteries. It showed a discharge capacity of 180 mAh/g at the 2nd cycle and it decreased to 150 mAh/g at the 10th cycle. Diffusion coefficients of lithium, (D) over bar(Li) in the carbon powder were measured by using two different electrochemical methods, i.e., the current pulse relaxation method (CPR) and the potential step chronoamperometric method (PSCA). The two sets of (D) over bar(Li) values agreed within one order of magnitude, and the observed (D) over bar(Li) value decreased from 2.5x10(-8) cm(2)/sec. at X=0.05 to 1.6x10(-9) cm(2)/sec. at X=0.4 with increasing X in LiXC6.