Fabrication of silicon nanoparticles/porous carbon@porous carbon nanofibers core-shell structured composites as high-performance anodes for lithium-ion batteries

Silicon-based electrodes hold a great potential application in lithium-ion batteries (LIBs) due to the high-energy -density. However, huge volume expansion and poor electric conductivity hinder the commercial application of silicon-based materials. To alleviate these problems, two different hierarchical core-shell composites, silicon/ carbon@porous carbon nanofibers (Si/C@PCNF) and silicon@hollow porous carbon nanofiber (Si@HPCNF) are designed and prepared through coaxial electrospinning. The shell layer prevents silicon contacting with elec-trolyte directly, and the porous carbon nanofibers shorten Li+ diffusion distance and facilitate ion transport. Compared with Si@HPCNF composites, Si/C@PCNF composites achieve a better electrochemical performance owing to the high surface area (68.05 m2/g) and the fact that silicon nanoparticles are connected to each other by porous carbon in the core. The Si/C@PCNF electrodes deliver a large reversible capacity (842.1 mAh center dot g  1 after 500 cycles at 0.5 A center dot g  1), a good rate capability (1366.6 mAh center dot g  1 at 0.5 A center dot g  1) and an excellent cycle stability (420.3 mAh center dot g-1 at 2.0 A center dot g-1 after 1000 cycles), indicating that it can be served as a promising anode for high-performance LIBs.