The critical contribution of unzipped graphene nanoribbons to scalable silicon–carbon fiber anodes in rechargeable Li-ion batteries

Abstract We have incorporated graphene nanoribbons (GNRs) which are unzipped from multi-wall carbon nanotubes (MWCNT) into silicon–carbon (Si/C) nanofibers, not only to reinforce hybrid Si/C fibers, but also to increase the electrical conductivity and charge transport capability of fibers. We demonstrated that GNRs are promising components for improving the rechargeable Li-ion battery performance due to their unique nanostructures and properties. Water based electrospinning, an easily scalable and environmentally benign process, was utilized to fabricate GNR/Si/C fibers. The resulting fibers exhibited a high reversible capacity of more than 1800 mA h/g at 0.5 C, and an excellent performance of 1400 mA h/g with no capacity fading at a charge/discharge rate of 1 C. This outstanding performance should be attributed to the enhanced charge and mass transfer ability of fibers by incorporation of ultrathin, flexible, conductive, and high aspect ratio GNRs. Electrodes made with GNR/Si/C fibers are more durable than ones with Si/C fibers, and do not exhibit dramatic volume and morphology changes after cycling. Moreover, GNR/Si/C fiber anodes were tested in a full-cell configuration where they displayed a steady gravimetric capacity of ca. 1400 mA h/g anode for 25 cycles.