Co/S co-doped Li4Ti5O12 as lithium-ion batteries anode for high-rate

Abstract

The low capacity and low ion diffusion coefficient are issues that need further addressed in the practical application of Li4Ti5O12 (LTO) at high-rate. In this study, Co/S co-doped nano-LTO was prepared as an anode material for lithium-ion batteries using a sulfur-cobalt synergistic strategy. The XRD and XPS results showed that Co ions were doped into the Ti sites of LTO, while S ions were doped into the Ti and O sites. And the cell volume was expanded by Co/S co-doping, which was beneficial for inserting more Li+ into the 8a site in nano-LTO to increase the capacity. Meanwhile, the Co/S co-doping increased the Ti3+/Ti4+ ratio to improve the electronic conductivity, which was beneficial for electron transport. With the synergistic effect of ion co-doping and nanosizing, the Li+ diffusion coefficient was increased from 2.75 × 10−13 to 2.02 × 10−11 cm2 s−1, resulting in the first discharge-specific capacity of 163, 158.6 and 146.5 mA h/g for LPCS at 10 C, 20 C and 50 C. And the capacity retention rate of LPCS was 85.3 % after 1000 cycles at 20 C; at this time, the discharge-specific capacity remained at 135.3 mA h/g at 20 C, which was 1.43 times that of LTO.