Nitrogen-doped carbon-coated cotton-derived carbon fibers as high-performance anode materials for lithium-ion batteries

Nitrogen-doped carbon-coated cotton-derived carbon fibers (NC@CCFs) were prepared by using cotton fibers as substrate and ionic liquid [HMIm]N(CN)₂ as source of carbon and nitrogen. The scanning electron microscopy, EDS element map, and X-ray photoelectron spectroscopy indicated that N-doped carbon uniformly coated on cotton-derived carbon fibers and the N element was successfully doped into NC@CCFs materials. This structure effectively improved the structural stability of NC@CCFs. The highly conductive CCFs provided conductivity network for electron transport in the NC@CCFs. Nitrogen doping provided abundant active sites and introduced many defects, which increased the lithium storage active sites of NC@CCFs. Therefore, the NC@CCFs anode shows excellent cycle stability (614.3 mAhg⁻¹ at 0.5 C after 250 cycles) and rate performance when used in lithium-ion battery.