Double-shell-structured Si@SiO x @C composite material for long-life lithium-ion storage

Double-shell-structured Si@SiOx@C composite material was prepared by aqueous etching with ammonium hydroxide and citric acid pyrolysis. The combination of Si with a double shell of SiOx and carbon shell has outstanding structural advantages. As Si anode has high specific capacity, SiOx is more stable during cycling and carbon has high conductivity. The excellent stability of SiOx during cycling compared with Si is profit from Li-oxide and Li-silicate generated by the reaction of Li+ with Si and O elements, which help to lead excellent cyclic performance. The Si@SiOx@C composite electrode demonstrates excellent electrochemical performance with high cyclic stability. The composite electrode has an initial reversible specific capacity of 575.3 mAhg−1 and capacity retention as high as 74.7% even after 400 cycles. The method used for the preparation of double-shell-structured Si@SiOx@C composite is easy and mass-productive, which could be applied for long-life lithium-ion battery anode materials.