PO43− doped Li4Ti5O12 hollow microspheres as an anode material for lithium-ion batteries

Abstract

Li₄Ti₅O₁₂ has been considered as one of the most promising alternative anode materials for high power lithium ion batteries due to its excellent cycle life and good safety. In particular, the superior high-rate capability of Li₄Ti₅O₁₂ is indispensable for practical application in high power batteries. Herein, in order to enhance the high-rate capability of Li₄Ti₅O₁₂, Li₄Ti₅O₁₂ hollow microspheres are successfully prepared via a template method and solid-state reaction by annealing in an argon atmosphere. Importantly, doping with larger PO₄³⁻ anions is introduced to improve the kinetics of the Li₄Ti₅O₁₂ anode materials. The microstructure and morphology of the as-prepared Li₄Ti₅O₁₂(PO₄)_x (x = 0, 0.01, 0.02, and 0.03) hollow microspheres are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. It is demonstrated from the electrochemical measurements that the as-prepared Li₄Ti₅O₁₂(PO₄)_0.02 sample manifests optimized electrochemical performance, including better cycle stability and outstanding high-rate performance during cycling. In particular, Li₄Ti₅O₁₂(PO₄)_0.02 presents the discharge capacity of 117.6 mA h g⁻¹ at 50C rate, obviously larger than that (70.5 mA h g⁻¹) of the pristine Li₄Ti₅O₁₂ due to the improvement of the kinetics, including charge-transfer resistance and lithium ion diffusion impedance. As a consequence, Li₄Ti₅O₁₂(PO₄)_0.02 is considered as a promising anode material with superior high-rate performance for lithium ion batteries.