Electrochemical performance and lithium-ion intercalation kinetics of submicron-sized Li4Ti5O12 anode material

Highlights: ► Quantitative analysis of the structural stability for spinel by DFT methods. ► The excellent cycling stability of Li4Ti5O12 from the strong covalent bonding characteristic between Ti and O. ► The cell temperature affects the Li extraction reaction of the Li4Ti5O12. - Abstract: Submicron-sized Li4Ti5O12 anode was synthesized through a two-step solid-state reaction. The relationship between the structural properties, electrochemical performance discharged to 0 V and lithium-ion intercalation kinetics was discussed using the experiments as well as the first-principles calculations. Structural analyses reveal that Li4Ti5O12 synthesized by the two-step solid-state method has high phase purity. Scanning electron microscopy (SEM) shows that Li4Ti5O12 has a homogeneous size distribution in the range of 0.4–0.6 μm. The initial discharge capacity of Li4Ti5O12 is 234.6 mA h g−1 at 0.5 C rate between 0 and 2.5 V, and it is close to the theoretical capacity value. The high structure stability of Li4Ti5O12 is related to the strong covalent bonding characteristic between Ti and O according to the first-principles calculation. Electrochemical impedance spectroscopy (EIS) indicates that the charge transfer resistance of the Li4Ti5O12/Li cell evidently decreases with increasing of the temperature, and the apparent activation energies of Li4Ti5O12 electrode on the lithium diffusion process and the charge transfer are calculated to be 19.05 and 22.48 kJ mol−1, respectively.