Hard Carbon Fibers Pyrolyzed from Wool as High-Performance Anode for Sodium-Ion Batteries

In this paper, we first demonstrate that the wool from worn-out clothes can serve as a low-cost and easy-to-collect precursor to preparing high-performance hard carbons for Na-ion batteries. Morphological characterizations demonstrate that this wool-derived hard carbon presents well-defined and homogeneously dispersed fiber networks. X-ray diffraction results combined with high-resolution transmission electron microscopy analysis reveal that the interlayer space (d(002)) of the graphitic layers is 0.376 nm, sufficient for Na insertion into the stacked graphene layers. Electrochemical results show that the wool-derived hard carbon can deliver a high capacity of 303 mAh g−1 and excellent cycle stability over 80 cycles. This satisfactory electrochemical performance and easy synthetic procedure make it a promising anode material for practical SIBs.