Improvement of capacity retention of lithium secondary batteries using carbon-coated silicon particles as anode materials

This study aimed to improve the charge/discharge capacity retention rate of lithium-ion batteries by coating carbon on silicon, an anode material, using polyvinylidene difluoride (PVDF) to prevent the expansion of silicon. PVDF was used as a precursor for coating carbon on silicon particles produced by milling a silicon mass. Accordingly, a lithium-ion coin cell was manufactured and evaluated to measure the improvement in its discharge capacity retention rate. The presence of a crystalline carbon layer on the silicon particles coated using PVDF as a precursor was observed through scanning electron microscopy, energydispersive X-ray spectroscopy, Raman spectroscopy, and transmission electron microscopy analyses. Through charge and discharge experiments, the capacity retention rate was determined to be 0.5% before the carbon coating of the silicon particles, as compared with the initial capacity. This value increased to 44.0% after the carbon coating. Thus, it was observed that the capacity retention rate of lithium-ion secondary batteries can be improved by modifying silicon through carbon coating using PVDF. In future studies, this carbon coating method will be optimized and applied to silicon oxides, which will be used as an anode material for lithium-ion batteries.