(253g) Carbon-Coated Silicon Particles As Negative Electrodes for Lithium Cells

Authors: 
Yen, S. C., National Taiwan University

   Silicon is considered as one of the most promising negative electrode materials for Li-ion batteries due to its high theoretical capacities (~4200mAh/g), which is much higher than that of conventional graphite (372mAh/g) used in commercial Li-ion batteries. However, Si-based Li-ion battery exhibits low intrinsic electrical conductivity and dramatic volumetric expansion (~400%) during the lithiation process. To improve the stability of Si-based anodes, carbon-coated Si composite materials have been developed in this study, and we prepare a graphite and carbon-coated Si particles hybrid to overcome the poor cycling stability and enhance the intrinsic electrical conductivity. Efficient and low-cost thermal treatment has been employed to prepare the negative electrode materials. Initially, a liquid carbon precursor, was mixed with Si nanoparticles and graphite via ultra-sonication. Next, amorphous carbon coats Si nano-composites prepared by pyrolysis at 1000 oC for 2 hr in Argon atmosphere. This structure effectively suppresses the huge volumetric variation and improves the cycling stability. In addition, it keeps the electrode materials highly conductive. It has been found that the negative electrode of Si composites exhibit outstanding performance with specific capacity 711mAh/g after 51 cycles of charging-discharging cycling at 100mA/g.