Lithium intercalation properties of reassembled titanate/carbon composites

The lithium intercalation properties of reassembled titanate/carbon (acetylene black or carbon fibers) composites were examined and compared with those of reassembled octatitanate simply mixed with carbon particles or conventional octatitanate. Composites of reassembled titanate and carbon particles were prepared by reassembling tetratitanate nanosheets, which were synthesized through exfoliation and reassembly, by a reaction with HCl in colloidal suspension mixed with carbon particles, followed by heat-treatment. The composites with acetylene black exhibited a smaller capacity and a lower high-rate capability than those with carbon fibers due to the large amount of hydrated water in titanate. The composites with carbon fibers showed a pseudocapacitive lithium insertion behavior. The reversible capacity of the composites with carbon fibers was 190 mAh g(-1), which was higher than those of conventional octatitanate or reassembled octatitanate. A relatively high capacity of 135 mAh g(-1) was maintained at a high current density of 10 A g(-1), which corresponds to similar to 70% of the discharge capacity at a relatively low current density of 100 mA g(-1). The composites with carbon fibers exhibited an excellent performance as a high-rate lithium insertion electrode. (c) 2007 The Electrochemical Society.