Influence of a carbon coating on the electrochemical properties of lithium-titanate-based nanosized materials

The influence of treatment temperature and a carbon precursor on the formation of a Li4Ti5O12-based anodic material and its electrochemical characteristics as part of a lithium-ion battery have been investigated. It is demonstrated that the variation of annealing temperature and the addition of saccharose prior to final annealing allow for the variation of Li4Ti5O12 particle sizes. At annealing temperatures of 400–600°C, lithium titanate forms as part of an anatase titanium oxide composite. Thermogravimetry, Raman spectroscopy, and electrochemical testing results show that a preannealing of the sample at temperatures of no less than 400°C and the addition of saccharose with subsequent annealing in an inert atmosphere are required for the formation of a conducting carbon coating. The formation of the carbon coating facilitates the inclusion of the anatase phase into the charging and discharging processes, which significantly increases the electrochemical capacity of samples obtained at low annealing temperature. The highest electrochemical capacity values (140 mA h/g) of anodic Li4Ti5O12 samples were obtained only after annealing at 800°C. We note the unexpected formation of carbon nanotubes in samples with a final annealing temperatures of 600°C.