Enhanced potassium storage of carbon nanofibers as binder-free anodes enabled by coupling ultra-small amorphous Sb₂O₃, graphene modification and sulfur doping

Considering the intrinsic advantages of natural copiousness and cost-effectiveness of potassium resource, potassium-ion batteries (KIBs) are booming as prospective alternatives to lithium-ion batteries (LIBs) in large-scale energy storage scenarios. Nevertheless, lacking desirable electrodes for reversibly hosting the bulky K⁺ hinders the widespread application of KIBs, and it needs to be urgently solved. Hereon, the porous S-doped Sb₂O₃-graphene-carbon (SAGC) nanofibers are manufactured through an adjustable and facile approach, which involves electrospinning, in situ etching and sulfuration. The synthesized SAGC is featured by the ultra-small amorphous Sb₂O₃ homogeneously wrapped inside the carbon matrix, as well as the co-incorporation of graphene and sulfur. Tentatively, the SAGC nanofiber sheets are applied as binder-free anodes for KIBs, exhibiting a prominent cycling life (256.72 mAh·g⁻¹ over 150 cycles at 100 mA·g⁻¹) and rate ·g⁻¹ over 100 cycles at 1 A·g⁻¹). The positive synergy among all the active components accounts for the distinguished performances of the SAGC. By reinforcing the tolerability to the swelling stress, producing the valid electrochemical active sites, and promoting the charge transferring for reversible K⁺ uptake, the SAGC finally renders the excellent cyclability, capacity, and rate capability. Moreover, the extrinsic electrochemical pseudocapacitance characteristics induced by the porous carbon substrate elevate the K-storage capacity of the SAGC as well. It is hoped that the conclusions drawn may offer new insights into a direction for the high-performance binder-free KIB anodes.