Enhanced Rate Capability and Low-Temperature Performance of LiTiO Anode Material by Facile Surface Fluorination.

A commercial LiTiO material was modified by NHF using a facile and dry method at a low temperature in air. X-ray diffraction reveals that the fluorination did not change the bulk structure of LiTiO. X-ray photoelectron spectroscopy demonstrates that LiF was formed at the surface and Ti was partially changed into Ti. Microscopic images show that some nanoislands were formed on the surface, which enlarged the surface area. Consequently, the NHF-modified LiTiO material exhibited significantly enhanced capacities and rate capabilities, even at low temperatures. The discharge capacity was increased from 149 to 167 mA h g at 1 C, and the capacity retention was increased from 17.8 to 52.0% at 15 C. The capacity retention of NHF-modified LiTiO was greater than that of LiTiO at each low-temperature point. Additionally, the introduction of F can protect the LiTiO material from side reactions with the electrolyte and the atmosphere, enhancing the surface stability and reducing the release of gaseous products. It is believed that the NHF-modified LiTiO with enhanced electrochemical performance is a promising anode material for lithium ion batteries. Furthermore, this facile surface fluorination strategy is amenable to large-scale production.