Electrospun nitrogen-doped carbon nanofibers with tuned microstructure and enhanced lithium storage properties

Abstract

Nitrogen-doped carbon materials hold great potential for high-performance lithium storage. However, the excess defects introduced by dominated nitrogen doping methods may lead to a thickened solid electrolyte interphase (SEI), resulting in a higher Li+ diffusion resistance and inferior rate performance. Herein, composite carbon nanofibers (CNFs) with tuned microstructure and relatively high nitrogen content were fabricated by co-electrospinning the mixture of nitrogen-rich pitch, a soft carbon precursor, with polyacrylonitrile (PAN) in controlled mass ratio. The result shows that the SEI formed on the composite CNFs with less surface defects is much thinner yet tighter than that formed on the PAN-based CNFs. As such, the composite CNFs present a double capacity retention of 37.3% to that of the PAN-based CNFs at 10 A g−1. More importantly, the cycle retention of the composite CNFs anode is 88.0% after 1000 cycles at 2 A g−1, much higher than that of PAN-based CNFs (61.5%). It is believed that the improved rate and cycle performance are due to the superior structure and chemical composition of the SEI, which can be attributed to the modified microstructure by addition of nitrogen-rich pitch to a great extent.