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

Chang, Chien-Min, Chen, Yi-Chih, Ma, Wei-Lun, Wang, Pin-Han, Lee, Ching-Feng, Chen, Hwang-Sheng, Chen-Yang, Yui Whei
RSC advances 2015 v.5 no.91 pp. 74381-74390
absorption, anodes, carbon, desorption, electric potential difference, electrochemistry, lithium batteries, nanoparticles, nitrogen, porosity, scanning electron microscopy, sol-gel processing, soot, surface area
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 N₂ 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 m² 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.