Sulfur‐Enriched Pitch‐Based Carbon Nanofibers With Lotus Root‐Like Axial Pores for Boosting Sodium Storage Performance

ABSTRACT Pitch is a promising precursor for preparing carbon materials for anode of sodium‐ion batteries. Heteroatom doping is an effective way to increase the sodium storage capacity while constructing reasonable pores and nanosizing the carbon skeleton help to achieve a high‐rate performance of anodes. In this work, sulfur‐doped carbon nanofibers with lotus root‐like axial pores were prepared using coal liquefaction pitch as the main precursor by electrospinning, pre‐oxidation, sulfurization, and carbonization. A considerable content of 7.41 wt.% of sulfur was doped into the carbon skeleton after low‐temperature gas‐phase sulfurization and subsequent carbonization. The as‐prepared sulfur‐doped porous carbon nanofiber films, used as self‐supporting electrodes of sodium‐ion batteries, display high specific capacity (528.5 mAh g −1 at 25 mA g −1 ), high‐rate performance (209.3 mAh g −1 at 500 mA g −1 ) and exceptional cycling stability (96.97% of retention at 500 mA g −1 over 1000 cycles). With desirable flexibility and excellent sodium storage performance, the achieved sulfur‐doped porous carbon nanofibers hold great promise for potential applications as self‐supporting anodes of sodium‐ion batteries.