eV and 530.0 eV , which likely stems from the reduction of the electrolyte. The peaks at 289.0 eV in C 1s, 532.9 eV in O 1s and 55.1 eV in Li 1s (Fig. ) are related to Li2CO3 . It is noted that signal of Li2CO3 in Si-SiOx@C-1.25 is weaker than Si-SiOx@C, indicating that the SEI layer on the surface of Si-SiOx@C has the relatively lower content of Li2CO3. In F 1s (Fig. ), the peaks ranging from 686 to 688 eV are related to LixPFy, which can further be further be reduced to LiF, while the corresponded peaks of LiF are at 55. difference of O 1s and Li 1s between Si-SiOx@C and Si-SiOx@C-1.25 is the existence of peaks related to Li2O in Si-SiOx@C-1.25, which locate at 528.6 eV in O 1s and 54.2 eV in Li 1s . Hence, based on the XPS results, the SEI layer of Si-SiOx@C-1.25 contains lower content of Li2CO3 and Li2O, which Si-SiOx@C doesn't have. With the presence of excess lithium atoms from the counter electrode, electrolyte decomposes to form Li2CO3 and Li2O. Furthermore, the obtained Li2CO3 is not stable and continues to form Li2O . These processes produce CO2 increasing the porosity of anodes and thicken the SEI layer, causing the decay of battery performance. The low content of Li2CO3 on the surface of Si-SiOx@C-1.25 reduces the following decomposition to Li2O and increases the stability of SEI layer, forming denser and more homogenous SEI layer.