Advanced electrochemical properties of Mo-doped Li4Ti5O12 anode material for power lithium ion battery

Abstract

Mo6+-doped Li4Ti5−xMoxO12 (0 ≤ x ≤ 0.2) samples have been synthesized via a simple solid-state reaction. The products were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electronic microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge testing. Li4Ti5−xMoxO12 (x = 0, 0.05) shows the pure phase structure, but several impurity peak can be detected when x ≥ 0.1. Mo-doping did not change the electrochemical reaction process and basic spinel structure of Li4Ti5O12. The particle size of the Li4Ti5−xMoxO12 (0≤ x ≤ 0.2) sample was about 2–3 μm and Li4Ti5O12 has less agglomeration. Electrochemical results show that the Mo6+-doped Li4Ti5O12 samples display a larger diffusion coefficient of lithium ions, lower charge transfer resistance, higher rate capability and excellent reversibility. The Li4Ti5−xMoxO12 (x = 0.1, 0.15) sample maintained considerable capacities until 6 C rates, whereas pristine Li4Ti5O12 shows a severe capacity decline at high rates. After 100 cycles, the specific reversible capacities of Li4Ti5O12 and Li4Ti4.9Mo0.1O12 are 195.8 and 210.8 mAh g−1, respectively. The superior cycling performance and wide discharge voltage range, as well as simple synthesis route and low synthesis cost of the Mo-doped Li4Ti5O12 are expected to show a potential commercial application.