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

Li4Ti5O12 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 Li4Ti5O12/carbon nanotubes (CNTs) is prepared by mixing powders of Li4Ti5O12 and CNTs in different weight ratios. Before mixing, in order to disperse CNTs in Li4Ti5O12 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 Li4Ti5O12:CNTs weight ratios of 94:1, 92:3, 90:5, 88:7 respectively at 0.1 C discharge rate for the Li4Ti5O12 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.