An-Na Zhou

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

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.

Synthesis and physicochemical properties of LiLa0.01Mn1.99O3.99F0.01 cathode materials for lithium ion batteries

Abstract Spinel lithium manganese oxide cathode materials were synthesized using the ultrasonic-assisted sol-gel method. The synthesized samples were investigated by differential thermal analysis (DTA) and thermogravimetry (TG), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and the charge-discharge test. TG-DTA shows that significant mass loss occurs in two temperature regions during the synthesis of LiLa 0.01 Mn 1.99 O 3.99 F 0.01 . XRD data indicate that all samples exhibit the same pure spinel phase, and LiLa 0.01 Mn 1.99 O 3.99 F 0.01 and LiLa 0.01 Mn 1.99 O 4 samples have a better crystallinity than LiMn 2 O 4 . SEM images indicate that LiLa 0.01 Mn 1.99 O 3.99 F 0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution. The charge-discharge test reveals that the initial capacities of LiMn 2 O 4 , LiLa 0.01 Mn 1.99 O 4 , and LiLa 0.01 Mn 1.99 O 3.99 F 0.01 are 130, 123, and 126 mAh·g 1 , respectively, and the capacity retention rates of the initial value, after 50 cycles, are 84.8%, 92.3%, and 92.1%, respectively. The electrode coulomb efficiency and CV reveal that the electrode synthesized by the ultrasonic-assisted sol-gel (UASG) method has a better reversibility than the electrode synthesized by the sol-gel method.