Cai-Bo Yue

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.

Structure and Electrochemical Performance of Niobium-Substituted Spinel Lithium Titanium Oxide Synthesized by Solid-State Method

Niobium-substituted Li 4 Ti 5―x Nb x O 12 electrodes (0 ≤ x ≤ 0.25) have been synthesized by a solid-state method. The structure and electrochemical performance of these as prepared powders have been characterized by differential thermal analysis (DTA) and thermogravimetery (TG), X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and the galvanostatic charge―discharge test. The XRD and RS results show that the Nb 5+ can partially replace Ti 4+ and Li + in the spinel and there are very few oxygen vacancies in the Li 4 Ti 4.95 Nb 0.05 O 12 with a higher electronic conductivity. The Nb-doped lithium titanium oxide samples show smaller particle size and more regular morphology structure, and Li 4 Ti 4.95 Nb 0.05 O 12 has the highest initial discharge capacity and cycling performance among all the samples cycled between 0.0 and 2.0 V. CV implies that the niobium doping is beneficial to the reversible intercalation and deintercalation of Li + . EIS indicates that Li 4 Ti 4.95 Nb 0.05 O 12 has a smaller charge transfer resistance corresponding to a much higher conductivity than that of Li 4 Ti 5 O 12 corresponding to the extraction of Li + ions. The superior cycling performance and wide discharge voltage range, as well as simple synthesis route and low synthesis cost of the Li 4 Ti 4.95 Nb 0.05 O 12 are expected to show a potential commercial application.