Influence of Sc3+ doping in B-site on electrochemical performance of Li4Ti5O12 anode materials for lithium-ion battery

Anode materials Li4Ti5O12 (LTO) and Sc-doped Li4Ti4.95Sc0.05O12-δ (LTSO) for lithium-ion batteries are both successfully synthesized by the modified sol-gel method with ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as a bi-components chelating agent. The samples are characterized by XRD, BET, XPS, EDX and SEM. The dopant Sc totally enters into the 16d sites of the spinel structure of LTO, and then further affects its morphology and property. The LTSO powder exhibits a 3D network morphology and its grain size is about 200 nm. The LTSO electrode material exhibits an excellent initial discharge capacities of 174 and 94 mAh g−1 at 1 C and 40 C, respectively. The reversible capacities of LTSO at different current rates remain nearly 100% after 50 cycles, which are compared with the capacities of the second cycles. Sc3+ doping can greatly improve the electronic conductivity of LTO which is demonstrated by electrochemical impedance spectroscopy. Cyclic voltammetry measurements also reveal that LTSO has small polarization resistance due to the high electrical conductivity and Li-ion apparent diffusion rate.