Synthesis of Li4 Ti5 O12 with Tunable Morphology Using l-Cysteine and Its Enhanced Lithium Storage Properties.

Nitrogen and sulfur co-doped carbon-coated Li4 Ti5 O12 (denoted as LTO/NSC) was developed to enhance the electrochemical performance of LTO material. l-Cysteine served as both the carbon source and the heteroatom doping source. The morphology of LTO was tuned by Ti-C bond formation during carbonation process, accompanied by a change in the original orientation growth of the LTO lattice plane. Consequently, LTO transformed from nanosheets to nanoparticles. SEM data proved that the structure of LTO/NSC nanoparticles was more stable than that of LTO nanosheets after hundreds of charge/discharge process. The N,S co-doped carbon layer can moderate particle aggregation and may help to shorten the electron transport length and enhance lithium storage capacity. The structural superiority and the N,S co-doped carbon layer endows LTO/NSC particles with high reversible specific capacity (183 mA h g-1 at 0.1 C), significantly enhanced rate capability (122 mA h g-1 at 10 C) and excellent cycling stability (capacity retention of 96.3 % after 200 cycles) relative to these features of LTO nanosheets. Thus, LTO/NSC is a promising anode material for high-performance lithium ion batteries.