Ce3+-doped Li4Ti5O12 with CeO2 surface modification by a sol-gel method for high-performance lithium-ion batteries

Aliovalently Ce3+-doped Li4Ti5O12 (LTO) is firstly synthesized by a sol-gel method using Ce(CH3COOH)3 as the dopant and CH3COOLi/(C4H9O)4Ti as starting materials. The structure and morphology of Ce3+-doped LTO with various doping level (Li4Ti5-xCexO12; x = 0, 0.05, 0.10, 0.15 and 0.20) are characterized by XRD, EDX, Raman, XPS, SEM and TEM. Pure phase Ce3+-doped Li4Ti5O12 is obtained when x ≤ 0.10, while CeO2 impurity is observed when x > 0.10. The Ce3+-doped LTO with appropriate content of CeO2 impurity shows much improved rate capability and specific capacity compared with the pristine and Ce3+-doped LTO without CeO2 impurity. Particularly, the Li4Ti5-xCexO12 (x = 0.15) electrode exhibits the best rate capability and long-term cycling stability among all samples, delivering a capacity of 120.0 mAh g−1 at 5C even after 1000 cycles. This work demonstrates that aliovalently Ce3+-doping is an effective approach for enhancing LTO's rate-performance.