1. Schematic illustration of the production of Si@C-F

2. (a) XRD patterns, (b) Raman spectra, (c) XPS survey scan, (d) high-resolution F1s and (e) Si2p XPS spectra of Si@C and Si@C-F, (f) TGA curve of Si@C-F

3. (a-c) SEM images, (d-f) TEM images and (g-i) elemental mapping of Si@C-F

4. (a, b) CV curves at a scan rate of 0.1 mV·s^-1 and charge-discharge voltage curves at (c, d) 0.2 and (e, f) 0.4 A·g^-1 for (a, c, e) Si@C and (b, d, f) Si@C-F anodes

5. (a) Cycling stability at a current density of 0.4 A·g^-1 with anodes activated by 4 cycles at 0.2 A·g^-1 before cycling, and (b) rate capability at various current densities ranging from 0.2 to 5.0 A·g⁻¹ and (c) capacity retention at a current density of 0.2 A·g^-1 for lithium storage in Si@C and Si@C-F anode

6. Cycling stability of Si@C-F anodes with different F ratios at a current density of 0.4 A·g^-1 with anodes activated by 4-10 cycles at 0.2 A·g^-1 before cycling

7. Nyquist plots of the Si@C and Si@C-F anodes (a) before and (b) after cycling at a current density of 0.4 A·g^-1

8. Top SEM images of (a) Si@C and (d) Si@C-F anodes after cycling; Cross-section SEM images of (b, c) Si@C and (e, f) Si@C-F anodes (b, e) before and (c, f) after cycling; High-resolution (g) F1s and (h) Li1s XPS spectra of SEI on Si@C and Si@C-F anodes after cycling

Table 1. Comparison of Si@C-F anode with reported Si-based anode in electrochemical performance