In this study, an anode composite material was fabricated by embedding spherical carbon-coated nanosilicon (Si@C) into a layered carbon-coated silicon (L-Si/C) to enhance the capacity and stability of silicon-based lithium-ion batteries. The L-Si/C material was obtained by reacting CaSi2 through a CO₂-assisted carbonization process, followed by removal of the CaCO3 byproduct via HCl etching. Si@C particles, prepared using polydopamine as a carbon precursor, were uniformly embedded in the L-Si/C via ultrasonic treatment. The physical properties of the prepared anode composites were analyzed using HR-SEM, EDS, XRD, and BET. The electrochemical performances were investigated using 1 M LiPF6 in EC:DEC (1:1 vol%) with 10 wt% FEC as the electrolyte, through charge–discharge cycling, rate capability tests, electrochemical impedance spectroscopy (EIS), and differential capacity (dQ/dV) analysis. L-Si/C exhibited the best electrochemical performance under the thermal treatment condition of 720 °C and a CO2 flow rate of 100 sccm. In addition, the application of ultrasonic treatment improved structural stability and rate capability. Consequently, the S_L-Si/C + Si@C-2 exhibited a high initial discharge capacity of 2700.7 mAh/g at 0.1 C and a capacity of 617.4 mAh/g at a high rate of 6 C.

Electrochemical characteristics of layered carbon-coated silicon anode composites embedded with Si@C for Li-ion batteries
    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Synthesis of S_L-SiC + Si@C
        2.2 Materials characterization
        2.3 Electrochemical characterization
    3 Results and discussion
        3.1 Characterization of S_L-SiC + Si@C
        3.2 Electrochemical performance of S_L-SiC + Si@C
    4 Conclusion
    References

• Kang Mi Lee(Department of Chemical Engineering, Chungbuk National University, Cheongju 28644, Republic of Korea)
• Jong Dae Lee(Department of Chemical Engineering, Chungbuk National University, Cheongju 28644, Republic of Korea) Corresponding author