LiF as an Artificial SEI Layer to Enhance the High-Temperature Cycle Performance of Li4Ti5O12

Li4Ti6O12 (LTO) is a promising anode Material for electric vehicles (EVs) and electrochemical energy storage applications because of its safety, good rate capability, and long cycle life. At elevated temperature, such as 60 degrees C, it always shows poor cycle performance because of the instability between the electrode material and electrolyte, which may also lead to a serious gassing issue. In this article, a facile hydrothermal method is adopted to coat the LTO powder with a thin LiF layer, in which the LiF acts as an artificial, solid electrolyte interface (SEI) layer to prevent the direct contact of LTO and electrolyte, thus improving the high-temperature cycle performance. Electrochemical tests prove that the LiF coating layer has no influence on the kinetics at ambient temperature and greatly enhances the high-temperature cycle stability, and the LTO@LiF composite material keeps 87% of its initial discharge capacity in 300 1C cycles at 60 degrees C. Moreover, the LiF coating layer exhibits a special self-driven reforming process during the initial cycles, which makes it uniform and more effective at enhancing the stability between electrode/electrolyte interfaces.