In-situ self-assembly synthesis of low-cost, long-life, shape-controllable spherical Li4Ti5O12 anode material for Li-ion batteries

Abstract

Li4Ti5O12 (LTO) is the most promising anode material for lithium-ion batteries owing to its excellent cycle stability and safety. However, the electrochemical performance of LTO at high rates is limited by its low conductivity. Generally, LTO preparation requires organic titanium sources, which are expensive. In this study, inexpensive H2TiO3 was used as the titanium source, LiOH‧H2O served as the lithium source, and NH3‧H2O was added to control the pH of the solution. Simple one-step liquid-phase deposition and calcination were performed for obtaining in situ self-assembled LTO submicron spheres with stable morphology and excellent electrochemical performance. According to electrochemical performance tests, the sample calcined with 4 mL of 25% NH3‧H2O at 700 °C (LTO-4–700) exhibited the best performance. Its discharge capacity remained at 176.4 mAh g−1 over 100 cycles at 87.5 mA g−1 and retained at 136.7 mAh g−1 over 500 cycles at 875 mA g−1, and its specific capacity was 105.6 mAh g−1 over 1000 cycles, even at a current of 1750 mA g−1 with a retention rate of 96.7%. Furthermore, LTO-4–700 exhibited excellent rate performance at 3500 mA g−1 compared to other samples. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed that submicron spherical LTO-4–700 had a high Li+ migration rate and low electrochemical impedance.