Highly enhancement of the SiO_x nanocomposite through Ti-doping and carbon-coating for high-performance Li-ion battery

Lithium-ion batteries (LIBs) with SiO_x anodes possess high energy density, stemming from the Li-Si alloying reaction. However, several issues hinder the application of SiO_x anodes in commercialized LIBs. In particular, the low electronic conductivity and sluggish kinetics of SiO_x result in inadequate electrochemical performance. Herein, we report the use of a selective alcoholysis-based reaction to prepare a (C-Ti_xSi_1-xO_y)@C composite using SiCl₄, TiCl₄, and ethylene glycol (EG) with benzene. The preferential reaction between EG and TiCl₄ results in Ti³⁺ doping as well as the formation of a homogenous distribution of Ti ions. During the selective alcoholysis reaction, the Ti-Si-O-C-H sol transforms into a (C-Ti_xSi_1-xO_y)@C composite and benzene decomposes into conductive carbon matrices through dispersion forces. The combination of Ti doping and carbon coating greatly enhance the conductivity of SiO_x; in addition, the incorporated carbon acts as an effective oxide buffer, preventing structural degradation. Thus, the (C-Ti_xSi_1-xO_y)@C composite exhibits a high Li-ion diffusion coefficient and low charge-transfer resistance, resulting in excellent capacity retention of 88.9% over 600 cycles at a high current density of 1 A g⁻¹ with a high coulombic efficiency of ∼99%.