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

Abstract

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.