Figure 1 XRD patterns of the products along with the synthetic process: (a) Mg2Si; (b) the sample annealed at 700 °C for 20 h in air; (c) after washing by HCl solution for 4 h.

Figure 2 images (a), (b), (c) and EDX pattern (d) of the Si/SiO2/C particles

Figure 3 TEM (a), (b), (c) and HRTEM images (d) of the Si/SiO2/C particles.

Figure 4Element mapping of a porous Si/SiO2/C particles.

Figure 5 (a) First three CV plots of the porous Si/SiO2/C particles at the scan rate of 0.1 mVs-1;
(b) first two charge and discharge curves for the porous Si/SiO2/C particles at the current of 800 mAg-1 .

Figure 6 (a) Capacity versus cycling numbers of the porous Si/SiO2/C particles at the testing current of 800 mAg-1;
(b) Rate capability of the porous Si/SiO2/C particles.