Construction of in situ C/N/S co-doped mesoporous Li4Ti5O12 nanosheets for high-rate and large-capacity lithium-ion batteries

Abstract

The low capacity of Li4Ti5O12 (LTO) under high-rate charging/discharging limits its development in energy applications. Two-dimensional (2D) nanosheets equipped with mesopores offer promising opportunities to realize high-rate and long-term lithium-ion batteries. This paper successfully synthesized C/N/S co-doped lithium titanate nanosheets with rich oxygen vacancy concentration (CNSLTO) in a single step. C, N and S are doped into the LTO bulk phase, providing bulk oxygen vacancies and active sites. Partial Ti4+ conversion to Ti3+ is promoted by co-doping and introducing rich oxygen vacancies, improving the electrical conductivity. In addition, the effect of CTAB concentration on the morphology and electrochemical properties of the materials was studied experimentally. The optimized CNSLTO nanosheets have a relatively high specific surface area (99.38 m2 g−1) and numerous mesoporous, achieving outstanding performance and excellent cycling stability at high-rate as lithium-ion anode materials. The CNSLTO exhibits excellent rate capacity (171.7–152.6 mA h g−1 at 0.5–20 C) and cycling performance (97.6 % after 1000 cycles at 10 C). Additionally, the discharge-specific capacity of the LFP//CNSLTO full battery at 10 C (122.2 mA h g−1) was superior to the LFP//LTO (77.8 mA h g−1).