Effects of carbon coating from sucrose and PVDF on electrochemical performance of Li4Ti5O12/C composites in different potential ranges

The carbon coated nanoflower-like Li4Ti5O12/C composites were prepared via hydrothermal method followed by surface modification using sucrose or polyvinylidene fluoride (PVDF) as carbon sources. X-ray diffraction, SEM, TEM, Raman spectroscopy, TGA, and the electrochemical measurements were used for the materials characterization. Such modification leads to the formation of a high-conductive carbon coating. In the case of polyvinylidene fluoride use, fluorination of Li4Ti5O12 surface takes place also. As a result, electrochemical performance of the obtained composites is improved. In the potential range of 1–3 V, Li4Ti5O12, Li4Ti5O12/CPVDF, and Li4Ti5O12/Csucrose exhibit, respectively, the discharge capacities of 142.5, 154.3, and 170.4 mAh/g at a current of 20 mA/g and 57.2, 82.1, and 89.3mAh/g at a current of 3200 mA/g. When cycled in a potential range of 0.01–3 V, the discharge capacity of Li4Ti5O12/CPVDF increases up to 252 mAh/g at 20 mA/g.