Spray-pyrolyzed porous Si-SiOx-C composites as anode for lithium-ion batteries

Abstract

Nanostructured silicon based anode materials are attractive alternative for improving the lithium storage properties. However, capacity fading mechanisms are cannot avoidable because of low electronic conductivity and large volume changes of silicon based anode materials. Nevertheless, simple synthesis method for stable silicon nanostructures still remains as a challenge. Composite powder of the Si- SiO$_x$ -C were prepared by a one-pot synthetic process via spray pyrolysis, by adding citric acid to a precursor solution containing sodium hydroxide(NaOH) and silicon nanoparticles(SiNPs). Different ratio of Si and SiO$_x$ can be prepared by control of SiNP etching time with NaOH. Structure characteristic analysis indicates that the SiNPs were embedded in SiOx matrix which is buffer layer for the volume expansion, and mesoporous carbon covered individual Si- SiO$_x$ particle. The mesopores existing in the carbon and SiO$_x$ matrix accommodates the volume expansion of silicon and thus capacity fading mechanisms can be improved. The first discharge capacity and initial Coulombic efficiency of the Si- SiO$_x$ -C were 1572mAh g$^{-1}$ and 76.5%. After 200 cycle at 1C, 1034.6 mAh g$^{-1}$(i.e., 1333.6 mAh g$^{-1}$) is maintained, and average Coulombic efficiency is 99.87%. This study suggests that simple spray pyroysis methods could be adaptable for Si- SiO$_x$ -C nanocomposites synthesis as anode materials of lithium-ion batteries.