Synthesis of carbon-coated Li4Ti5O12 nanosheets as anode materials for high-performance lithium-ion batteries

Pristine and carbon-coated Li4Ti5O12 nanosheets are synthesized by a hydrothermal process, followed by calcination at 750 °C for 10 h. The structural properties of the as-prepared composites are characterized systematically by X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and N2 adsorption-desorption analysis, respectively. Electrochemical lithium insertion/extraction performances are evaluated by the galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV), respectively. In comparison, Li4Ti5O12@C exhibits higher specific capacity, better rate capability and capacity retention than the pristine Li4Ti5O12. Analysis from the electrochemical measurements indicates that the enhanced electrochemical performances Li4Ti5O12@C might be attributed to the shorter Li-ion diffusion distance, lower charge-transfer resistance, better electrode kinetics and lower activation energy as a result of thinner nanosheet and the presence of carbon layer.