Effect of Silicon Crystal Size on Electrochemical Properties of Magnesium-Doped SiOx Anode Materials for Lithium-Ion Batteries

This study aims to fabricate magnesium-doped SiOx materials through the integrated application of physical vapor deposition and chemical vapor deposition techniques, with the objective of developing high-performance anode materials for lithium-ion batteries. With the macroscopic particle size held constant, this study endeavors to explore the impact of variations in the size of microscopic silicon crystals on the properties of the material. Under the effect of magnesium doping, the influence mechanism of different microscopic grain sizes on the reaction kinetics behavior and structural stability of the material was systematically studied. Based on the research findings, a reasonable control range for the size of silicon crystals will be proposed. The research findings indicate that both relatively small and large silicon crystals are disadvantageous for cycling performance. When the silicon crystal grain size is 5.79 nm, the composite material demonstrates a relatively high overall capacity of 1442 mAh/g and excellent cycling stability. After 100 cycles, the capacity retention rate reaches 83.82%. EIS analysis reveals that larger silicon crystals exhibit a higher lithium ion diffusion coefficient. As a result, the silicon electrodes show more remarkable rate performance. Even under a high current density of 1C, the capacity of the material can still be maintained at 1044 mAh/g.