Sol-gel synthesis of low carbon content and low surface area Li4Ti5O12/carbon black composites as high-rate anode materials for lithium ion batteries

Li4Ti5O12/carbon black composite anode materials (LTO/CB) with various amounts of carbon black (CB) as an extra carbon source are synthesized by the sol-gel method. The SEM images show that micron-sized clusters are formed by Li4Ti5O12 nanoparticles with diameters of 5-15 nm. The N-2 absorption/desorption measurements indicate that the total pore volume and pore size of LTO/CB with only 3.04 wt% carbon content (LTO/CB-2) are significantly increased, improving the electrochemical properties, and the surface area is only 3.64 m(2) g(-1), benefiting the electrode processing. The discharge capacities of the LTO/CB-2 electrode in the voltage range of 1-2.5 V at 1, 2 and 5C rates are 221, 200 and 156 mA h g(-1), respectively and, even after 150 cycles, it retains 214 mA h g(-1) at 1C. Moreover, for the coin full-cell tests, the discharge capacities for the (LTO/CB-2)/LiFePO4 battery at 0.2, 0.5 and 1C are 152, 149 and 133 mA h g(-1), respectively. These are the highest capacities at the rate of 0.2-5C among the carbon-containing LTO electrodes with low surface areas for half-cells reported up to now, indicating that LTO/CB-2 is a promising high-rate anode material for use in high-power lithium ion batteries.