Mechanical constraining double-shell protected Si-based anode material for lithium-ion batteries with long-term cycling stability

Si@SiO2@C core double-shell nanocomposites are successfully synthesized by a facile method. The inside shell of SiO2 with a stable mechanical structure can completely limit the volume expansion of Si during charge/discharge cycles and beneficial for a dense carbon shell formation on the surface of SiO2. The outside carbon shell serves as an effective electron conductor to enhance the electronic conductivity of the nanocomposite. This mechanical constraining double-shell protection is good for the electrode to form a stable solid electrolyte film during cycling. The Si@SiO2@C nanocomposites achieve outstanding long-term cycling stability and high rate performance. High capacity of 775 mAh g−1 is obtained after 1000 cycles at 1.0 A g−1 and 617 mAh g−1 after 400 cycles at 2.0 A g−1. The full-cell coupled with LiNi0.8Mn0.1Co0.1O2 cathode exhibits good cycling ability. This excellent electrochemical performance is much improved when compared with other Si/SiOx based anode materials. These structural features make the Si@SiO2@C as promising anode materials for high energy storage lithium-ion batteries.