Hybrid super-aligned carbon nanotube/carbon black conductive networks: A strategy to improve both electrical conductivity and capacity for lithium ion batteries

Super-aligned carbon nanotube (SACNT) films drawn from SACNT arrays are uniformly introduced into LiCoO2-Super P composite cathodes by a cold-rolling method, and a hybrid conductive network consisting of SACNTs and carbon black powders is obtained. This attempt results in reduced percolation threshold and increased conductivity of the LiCoO2-Super P cathodes with addition of less than 0.01 wt% of SACNTs. The strength and flexibility of the LiCoO2-Super P-SACNT composites can be improved significantly due to the excellent mechanical properties of SACNTs. The continuous SACNT films play an important role for the formation of a homogeneous network for long-range conductive pathways. Super P is also an essential component to form short-range conductive pathways. By comparing with control samples that only contain Super P or SACNT films, we demonstrate that the LiCoO2-Super P-SACNT composites possess the best cycling stability (150 mA h g(-1) at 0.1 C with a capacity retention of 99.7% after 50 cycles) and rate capability (87 mA h g(-1) at 5 C). Combining both short-range and long-range conduction, the hybrid Super P-SACNT conductive network manifests itself as a promising strategy to improve the battery performances with a minimum amount of conductive fillers. (C) 2013 Elsevier B.V. All rights reserved.