Investigation of carbon coating approach on electrochemical performance of Li4Ti5O12/C composite anodes for high-rate lithium-ion batteries

Abstract

Submicron-sized Li4Ti5O12/C (LTO/C) composites were successfully synthesized by using one-step and two-step route, in which sucrose was used as carbon precursor, and employed as anode materials for lithium-ion batteries (LIBs). The structure, surface morphology, and chemical compositions were characterized by X-ray diffraction, Raman spectroscopy, scanning, and transmission electron microscopy techniques. The electrochemical properties of the carbon-coated samples were examined by using the charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. It was found that the LTO/C synthesized by one-step method (designated as LTO/C-O) possessed smaller LTO/C particle size, more cohesive particle distribution, and more uniform conductive carbon layer on LTO surface compared with that synthesized by two-step method (LTO/C-T). As a result, the LTO/C-O electrode illustrated a high discharge capacity of 173.6 mAh g−1 at a charge/discharge rate of 0.1 C. Moreover, the discharge capacity retention of the LTO/C-O electrode can effectively deliver to 95.9, 90.9, 87.9, and 80.9%, whereas the LTO/C-T electrode exhibited 94.0, 79.9, 68.0, and 50.1% at 1, 5, 10, and 20 C, respectively. Therefore, the LTO/C-O can be considered as one of the promising anode materials for high-rate LIBs.