Structural and electrochemical characteristics of SiO2 modified Li4Ti5O12 as anode for lithium-ion batteries

• The SiO2 modification method is easy to carry out.
• The SiO2 coating layer could enhance the Li+ diffusion.
• The SiO2 coating layer could suppress the formation of SEI.
• The LTO modified with 2.5 mol% SiO2 exhibits the best electrochemical performance.

The commercial Li4Ti5O12 is modified with SiO2 directly via a simple sol–gel method. The SiO2 modified Li4Ti5O12 samples are characterized by a variety of means such as powder X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) mapping, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), galvanostatic charge–discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with pure Li4Ti5O12, the structure of SiO2 modified Li4Ti5O12 has no change, and there is a SiO2 coating layer over the Li4Ti5O12 particles. Appropriate amount of SiO2 could effectively reduce the electrochemical polarization of Li4Ti5O12 and enhance electrochemical reaction kinetics of Li+ insertion/deinsertion. As a result, the Li4Ti5O12 modified with 2.5 mol% SiO2 exhibits higher specific capacity and better rate capability. Moreover, the SiO2 coating layer is likely to cover the catalytic sites on the Li4Ti5O12 surface for the decomposition of electrolyte, thereby restraining the formation of solid electrolyte interphase (SEI), which is very favorable for improving the cycle performance of Li4Ti5O12. The SiO2 modification process is easy to control and carry out for industrialization, which could improve the electrochemical performance of Li4Ti5O12.

The SiO2 coating layer could effectively reduce the electrochemical polarization of Li4Ti5O12 and enhance electrochemical reaction kinetics of Li+ insertion/deinsertion. As a result, the Li4Ti5O12 modified with 2.5 mol% SiO2 exhibits higher specific capacity and better rate capability. Moreover, the SiO2 coating layer is likely to cover the catalytic sites on the Li4Ti5O12 surface for the decomposition of electrolyte, thereby restraining the formation of SEI, which is favorable to improving the cycling stability of Li4Ti5O12.Figure optionsDownload as PowerPoint slide