Dual yolk-shell structure of carbon and silica-coated silicon for high-performance lithium-ion batteries

• Published in: Scientific reports 2015-06, Vol.5 (1), p.10908, Article 10908
• Main Authors: Yang, L. Y., Li, H. Z., Liu, J., Sun, Z. Q., Tang, S. S., Lei, M.
• Format: Article
• Language: English
• Subjects: 639/638/161; 639/925/357/354; Carbon; Etching; Humanities and Social Sciences; Lithium; multidisciplinary; Science; Silica; Silicon; Yolk
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep10908

Silicon batteries have attracted much attention in recent years due to their high theoretical capacity, although a rapid capacity fade is normally observed, attributed mainly to volume expansion during lithiation. Here, we report for the first time successful synthesis of Si/void/SiO 2 /void/C nanostructures. The synthesis strategy only involves selective etching of SiO 2 in Si/SiO 2 /C structures with hydrofluoric acid solution. Compared with reported results, such novel structures include a hard SiO 2 -coated layer, a conductive carbon-coated layer and two internal void spaces. In the structures, the carbon can enhance conductivity, the SiO 2 layer has mechanically strong qualities and the two internal void spaces can confine and accommodate volume expansion of silicon during lithiation. Therefore, these specially designed dual yolk-shell structures exhibit a stable and high capacity of 956   mA h g −1 after 430 cycles with capacity retention of 83%, while the capacity of Si/C core-shell structures rapidly decreases in the first ten cycles under the same experimental conditions. The novel dual yolk-shell structures developed for Si can also be extended to other battery materials that undergo large volume changes.