Coaxial electrospun Si/C–C core–shell composite nanofibers as binder-free anodes for lithium-ion batteries

• Si/C-C core-shell nanofibers were designed by dual nozzle coaxial electrospinning.
• Carbon shell buffers volume change and restrains capacity fading of the Si/C core.
• Si/C-C core-shell nanofibers show high discharge capacity after prolonged cycling.

Si/C–C core–shell nanofiber structure was designed by dual nozzle coaxial electrospinning and subsequent carbonization. This core–shell nanofiber structure has Si/C composite as the core and carbon as the shell. Used as an anode in lithium-ion batteries, the carbon shell can help buffer the large volume expansion/contraction of the Si/C core during charge/discharge and restrain the capacity fading caused by the mechanical failure of the active material. Results showed that after 50 cycles, the discharge capacity of Si/C–C core–shell composite nanofibers was 63% higher than that of Si/C composite nanofibers and the capacity retention increased from 48.6 to 72.4%. It is, therefore, demonstrated that Si/C–C core–shell composite nanofibers are promising anode material with large reversible capacity and good cycling stability.