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

This study was designed to systematically investigate the influence of variations in the microscopic silicon crystal size on the electrochemical performance of pre-magnesium silicate anode materials, under the premise that the macroscopic particle size remains consistent. Through precise control of the macroscopic particle distribution of silicon materials, the study focused on exploring the mechanisms by which different microscopic grain sizes affect the reaction kinetics, structural stability during the pre-magnesium process, and the properties of the final composite products.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.