Abstract: Nanocarbon composites (NCCs), which were formed by sonication of multiwalled carbon nanotubes (MWCNTs) and acetylene black (AB), were used as a conducting additive in a LiCoO2 cathode for lithium ion batteries. The electrochemical performance of LiCoO2 cathode dispersed with NCC was investigated. The results showed that the electrochemical performance (including the initial discharge capacity and the capacity retention) of a NCCloaded LiCoO2 cathode were better than that of a cathode loaded with MWCNTs or AB, which can be ascribed to the superior conducting networks formed in NCC, compared to MWCNTs or AB, and the good and stable contact between NCC and LiCoO2 particles.