Revealing Rate Limitations in Nanocrystalline Li4Ti5O12 Anodes for High-Power Lithium Ion Batteries

Li4Ti5O12 is a promising anode material for lithium ion batteries due to its high safety, excellent cycling stability, environmental friendliness, and low cost. Strategies of incorporation with a conductive component (such as carbon) and constructing nano-structure are frequently adopted to improve the rate-capability of Li4Ti5O12 by means of enhancing the electronic conductivity and promoting the lithium ion transport within electrodes, respectively. However, which charge carrier transport process is the limiting step for Li4Ti5O12 electrode reactions still remains unclear, and this limits the abilities to rationally design high performance Li4Ti5O12 materials. In this work, the nanosized Li4Ti5O12 and Li4Ti5O12/C materials are prepared with nearly identical particle size and morphology. The results demonstrate that the synthesized single phase Li4Ti5O12 delivers a higher specific capacity and superior rate-capability than Li4Ti5O12/C composite. As such, in contrast to a popular belief, it is lithium ion transport that restricts kinetics of the electrochemical reactions on Li4Ti5O12. The synthesized single phase Li4Ti5O12 shows a specific capacity of approximate to 160 mAh g(-1) at 0.5 C and 130 mAhg(-1) at 50 C rates, respectively. This rate-capability is the best reported for Li4Ti5O12 anodes. The single phase Li4Ti5O12 also demonstrated remarkable stability at high-temperature (50 degrees C), showing cycling life of over 4000 cycles at 1 C.