Li4Ti5O12/CNTs composite anode material for large capacity and high-rate lithium ion batteries

Abstract Li 4 Ti 5 O 12 sub-micro crystallites are synthesized by ball-milling and one-step sintering under different heat treatment temperature from 700 °C to 900 °C. The composite electrode of Li 4 Ti 5 O 12 /carbon nanotubes (CNTs) is prepared by mixing powders of Li 4 Ti 5 O 12 and CNTs in different weight ratios. Before mixing, in order to disperse CNTs in Li 4 Ti 5 O 12 particles preferably, the CNTs are cut and dispersed by hyperacoustic shear method and the composite electrodes of low resistance of about 20–30 Ω are obtained. The composite electrodes have steady discharge platform of 1.54 V and large specific capacity, initial discharge capacities are 168, 200, 196, 176 mAh g −1 in different Li 4 Ti 5 O 12 :CNTs weight ratios of 94:1, 92:3, 90:5, 88:7 respectively at 0.1 C discharge rate for the Li 4 Ti 5 O 12 synthesized in an optimized heat treatment temperature of 800 °C. In our experimental range, the composite electrode in a CNTs weight ratio of 3:92 shows the best performance under different discharge rate such as the initial capacity is 200 mAh g −1 with discharge capacities retention rate of nearly 100%. Its capacity is about 151 mAh g −1 under 20 C rate discharge condition with excellent high-rate performance. There is almost no decline after 20th cycles under 10 C rate discharging condition.