Abstract:

In this work, silicon@reduced graphene oxide/pyrolytic carbon nanofibers (Si@RGO/C NFs) composite with double modified layer is prepared through electrospinning, stabilization and carbonization. In this composite, polyethylene oxide-polypropylene oxide-polyethylene oxide (P123, a non-ionic surfactant) is introduced as the dispersant, which can make silicon nanoparticles evenly dispersed in electrospinning solution to prevent it from agglomeration. Graphene modified layer can buffer the volumetric expansion of silicon nanoparticles, prevent direct contact between silicon and electrolyte as well as enhance the electrical conductivity. Moreover, carbon fibers synthesized by electrospinning can encapsulate silicon@graphene composite internally to form a double modified layer. This composite with double modified layer can further alleviate the volume change of silicon nanoparticles and avoid direct contact between silicon and electrolyte to form a stable interface. Owing to the above-mentioned merits, the Si@RGO/C NFs composite exhibits excellent cyclic stability and superior rate performance. Particularly, it maintains a specific capacity of 929 mA h g^-1 with the retention ratio of 83.1% after 100 cycles at 0.5 A g^-1 and delivers an outstanding rate capability of 1003 mA h g^-1 at 2 A g^-1.

Key words: Lithium-ion batteries, Silicon/carbon composite, Surface modification, Graphene, Electrospinning