Microstructural controls of titanate nanosheet composites using carbon fibers and high-rate electrode properties for lithium ion secondary batteries

Composite electrodes of reassembled titanate and two kinds of carbon fibers wire prepared and their high-rate electrode properties were examined Multi-walled carbon nanotubes (MWNT) and vapor-grown carbon fibers (VGCF) were used for preparing the composites The electronic conductivity of the MWNT composites increased with increasing contents of MWNT and exhibited a typical insulator-conductor transition The MWNT composite with a MWNT content of 50 wt% showed a capacity of 150 +/- 5 mAh (g titanate)(-1) at a discharge rate of 0 67C and did not show a good high-rate capability due to the large content of hydrated water The effect of the porous structure of the electrodes was revealed in the high-rate electrode properties of the microstructurally controlled composites with both MWNT and VGCF The composites with 50 wt % VGCF and 10 wt % MWNT showed a reversible capacity of approximately 160 mAh (g titanate)(-1) at a discharge rate of 0 63 C and almost no capacity fading at relatively large discharge rate up to 19C A composite electrode with excellent high-rate capability was obtained by the microstructural control with carbon fibers (C) 2010 Elsevier B V All rights reserved