Multi-component layer–protected Si-based composites with improved electrochemical performances as anode for Li-ion batteries

In this paper, Si-based composites coated by a multi-component layer have been synthetically prepared, via a solvothermal process, mechanical ball milling, and subsequent high-temperature calcination. The multi-component surface layer consists of an amorphous SiO_x/C layer with well dispersion of TiC and TiB₂ nanocrystals and amorphous TiO_x and B₂O₃. The introduction of titanium and boron species is beneficial for the improvement of mechanical stability of the coating layer and ensures the structural integrity of the electrode during cycling, consequently leading to excellent electrochemical performances. Therefore, the obtained Si-based composites exhibit much better high-rate performances and cycling stability than Si and Si/C electrodes. Si-based composites from 2.94 mmol tetrabutyl titanate deliver specific capacities of 1377, 1361, 1247, 1104, 949, 833, 669, and 526 mAh·g⁻¹ at 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 5.0, and 8.0 A·g⁻¹, respectively, and capacity retention of 76.7% after 500 cycles at 1 A·g⁻¹.