Effect of carbon nanotube on the electrochemical performance of C-LiFePO4/graphite battery

This paper describes the fabrication and testing of C-LiFePO4/graphite battery with different conductive carbon additives: carbon nanotube (CNT) or carbon black (CB). The discharge capacity, rate capability and cyclic performance of the battery were investigated. Compared with the batteries with CB additive, those with CNT additive show better electrochemical performances with capacity retention ratio of 99.2% after 50 cycles, and the ratio of discharge capacity at 0.1 C rate to that at 1 C rate is 94.6%. The reason for the difference in electrochemical property was studied with cyclic voltammagrams and AC impedance. It was found that, with CNT additive, the polarization voltage was decreased from 0.3 to 0.2 V, and the impedance was decreased from 423.2 to 36.88 Omega. The structures of active materials after cycling were characterized using XRD. The better crystal retaining of LiFePO4 was found in the active materials with CNT added. (C) 2008 Elsevier B.V. All rights reserved.