Improving the Cyclability and Rate Capability of Li4Ti5O12 Anode Material by Cu2+ and F- co-Doping

We report a new Li4Ti5-xCuxO11.7F0.3 (X=0.1, 0.15, 0.2, 0.25, 0.3) anodic material for use in Li-ion batteries. These modified Li4Ti5O12 (LTO) materials were prepared by solid-state method and calcination at 800 degrees C. The Li4Ti4.75Cu0.25O11.7F0.3 (LTCu0.25OF0.3), among all samples, shows the best results in cyclability and rate ability. The LTCu0.25OF0.3 delivers discharge capacities of 188.8, 180, 169.7, 151.2, 116, and 93.6 mAh g(-1) at 0.1, 0.2, 0.5, 1, 3, and 5C, respectively. The capacity retention of LTO, LTOF0.3, and LTCu0.25OF0.3 after 100 charge and discharge cycles at 1C is 90.8 %, 96.3 %, and 97.7 %, respectively. The enhancement in electrochemical performance of LTCu0.25OF0.3 is attributed to the lower polarization and charge transfer resistance (15.5 omega) and higher Li+ diffusion coefficient (6.4x10(-7) cm(2) s(-1)) obtained by cyclic voltammetry (CV) and electrochemical-impedance spectra (EIS) tests. This work indicates that Cu2+ and F- have a synergistic impact on the electrochemical properties of LTO.

Automated summary

We have reported a new anode material, Li4Ti5-xCuxO11.7F0.3 (X=0.1, 0.15, 0.2, 0.25, 0.3), for Li-ion batteries. Among these modified Li4Ti5O12 (LTO) materials, Li4Ti4.75Cu0.25O11.7F0.3 (LTCu0.25OF0.3) exhibits the best cyclability and rate ability. LTCu0.25OF0.3 delivers high discharge capacities at different current rates and shows excellent capacity retention after 100 charge and discharge cycles. The improved electrochemical performance is attributed to lower polarization and charge transfer resistance, as well as a higher Li+ diffusion coefficient.