Synergetic effect of carbon and AlF3 coatings on the lithium titanium oxide anode material for high power lithium-ion batteries

Abstract

A carbon coated commercial lithium titanium oxide (Li4Ti5O12; LTO) was acoustically mixed with nano-sized AlF3 and heat treated to form a simultaneous coating layer of carbon and AlF3 on LTO particles. The surface modified LTO samples were characterized by a variety of means such as X-ray diffraction, Fourier transform infrared spectrometer, high-resolution transmission electron microscope, and inductively coupled plasma mass spectrometry. The results indicate that both carbon and AlF3 layers exist on the surface of LTO particles and that the distribution of the carbon and AlF3 differs depending on post heat treatment temperature. The carbon and AlF3 coating layers formed by optimal post heat treatment at 350°C significantly improves electrochemical performance, which increases charge capacity by 30% over the pristine LTO after 50cycles at a high current density of 5C. Thus, LTO with a simultaneous coating layer of carbon and AlF3 formed by acoustic mixing and post heat treatment shows a potential to further improve commercially-optimized carbon-coated LTO by alleviating its inherently low conductivity. This is an effective way to stabilize the interface between LTO particles and electrolyte, and is a practical approach to promote the wide usage of LTO, one of the most potent anode materials.