Glucose Carbon Spheres Uniformly Coupled with Cotton‐Derived Carbon Nanofibers as Ultrafast Anodes for Sodium‐Ion Batteries

Abstract Glucose carbon spheres are uniformly coupled with cotton‐derived carbon nanofibers (GCS@C) through an eco‐friendly hydrothermal and carbonization approach. The meticulously designed structure of composite materials enables the GCS@C to have uniformly dispersed glucose carbon spheres, thereby enhancing active sites. Meanwhile, the cotton‐derived carbon nanofibers boost the conductivity of the electrode. As a result, GCS@C shows a high reversible capacity (247.1 mAh g −1 at 0.1 A g −1 ) and remarkable long cycle stability (with only a 0.05% attenuation in each cycle after 500 times at 2.0 A g −1 ). The results of in situ XRD show that the slope region mainly corresponds to the intercalation of sodium ions between carbon layers. This study offers an environmentally friendly process for synthesizing high‐performance sodium‐ion battery electrodes from biomaterials.