Synthesis and electrochemical performance of Li4Ti5O12 submicrospheres coated with TiN as anode materials for lithium-ion battery

The TiN coated Li4Ti5O12 (LTO) submicrospheres with high electrochemical performance as anode materials for lithium-ion battery were synthesized successfully by solvothermal method and subsequent nitridation process in the presence of ammonia. The XRD results revealed that the crystal structure of LTO did not change after thermal nitridation process. The submicrospheres morphology of LTO and TiN film on the surface of LTO submicrospheres were characterized by FESEM and HRTEM, respectively. XPS result confirmed that a small amount of Ti changed from Ti4+ to Ti3+ after nitridation process, which will increase the electronic conductivity of LTO. Electrochemical results showed that electrochemical performance of TiN coated LTO anode materials compared favorably with that of pure LTO. Also its rate capability and cycling performance were apparently superior to those of pure LTO. The reversible capacity of TiN-LTO is 105.2 mA h g−1 at a current density of 10 C after 100 cycles and maintain 92.9% of its initial discharge capacity, while that of pure LTO is only 83.6 mA h g−1 with a capacity retention of 90.3%. Even at 20 C, the discharge capacity of TiN coated LTO sample is 101.3 mA h g−1, compared with 77.3 mA h g−1 for pristine LTO in the potential range 1.0–2.5 V (vs. Li/Li+).