Pyrolytic carbon-coated silicon/carbon nanofiber composite anodes for high-performance lithium-ion batteries

• Si nano-particles exposed on fiber surface are protected by pyrolytic carbon.
• Carbon coating layer were formed via sucrose coating and secondary thermal treatment.
• Pyrolytic carbon-coated Si/C nanofiber show improved cyclical stability.

Pyrolytic carbon-coated Si/C nanofibers (Si/C-CNFs) composites have been prepared through the sucrose coating and secondary thermal treatment of Si/CNFs composites produced via electrospinning and carbonization. This results in a structure in which Si nanoparticles are distributed along the fibers, with the fiber surface being coated with an amorphous carbon layer through pyrolysis of the sucrose. This carbon coating not only limits the volume expansion of the exposed Si nanoparticles, preventing their direct contact with the electrolyte, but also creates a connection between the fibers that is beneficial to Li+ ion transport, structural integrity, and electrochemical conductivity. Consequently, the Si/C-CNFs composite exhibits a more stable cycle performance, better rate performance, and higher conductivity than Si/CNFs alone. The optimal level of performance was attained with a 20:200 mass ratio of sucrose to deionized water, with a high retained capacity of 1215.2 mAh g−1 after 50 cycles, thus indicating that it is a suitable anode material for Li-ion batteries.