Enhanced electrochemical performance of Li4Ti5O12 anode material by LaF3 surface modification for lithium-ion batteries

Abstract

The LaF3-modified Li4Ti5O12 materials have been synthesized via a chemical co-precipitation method, and the effects of different amounts of LaF3 modification (0.5 wt%, 1 wt%, 2 wt%, and 3 wt%) on the morphology, structure, and electrochemical performance of the Li4Ti5O12 (LTO) materials were investigated. X-ray diffraction and X-ray photoelectron spectroscopy (XPS) characterizations show that the La3+ or F− ions are not incorporated into the LTO particles, and major LaF3 and minor La2O3 peaks are observed in the LaF3-modified LTO samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that the generated LaF3/La2O3 nanoparticles are continuously wrapped around the surfaces of LTO particles. Charge-discharge tests reveal that the 1 wt% LaF3-modified LTO material (1LaFLTO) exhibits the highest rate capacity values among all of the samples of 199.9, 187.4 and 159.7 mAh g−1 at 3C, 5C, and 10C, respectively between 0 and 3 V. Moreover, 1LaFLTO also delivers superior cycling stability with a capacity retention of 94.5% after 300 cycles at 5C between 1 and 3 V. The electrochemical results demonstrate that the appropriate LaF3/La2O3 nanoparticles coated on the surface of 1LaFLTO particles not only reduce electrode polarization, SEI film resistance, and charge-transfer resistance but also accelerate Li+ diffusion and improve the reversibility, which is favorable for enhancing the electrochemical performance of LTO material.