Hierarchically porous carbon nanofiber binder-free electrode for high-performance lithium–sulfur batteries

Abstract

It is still a challenge for lithium–sulfur (Li-S) batteries to possess high sulfur utilization and excellent electrochemical performances due to the low electrical conductivity and dissolution of polysulfides. To resolve these issues, a free-standing sulfur host composed of hierarchically porous carbon nanofibers (HPCNFs) has been synthesized via electrospinning technology. The HPCNFs with an interconnected and porous structure can facilitate electron transfer and electrolyte penetration. The mesopores in HPCNFs can provide high levels of sulfur loading, and the micropores can inhibit shuttle effects of the sulfur cathode during discharge and charge processes. After encapsulating a high mass of sulfur (76.4 wt%, HPCNFs@S), the electrode was directly applied as a cathode for the Li-S battery, which exhibited a high specific discharge capacity of 1,145 mA h g −1 at 0.1 C (1 C = 1,675 mA g −1 ) and maintained 787 mA h g −1 after 150 charge/discharge cycles. This work provides a new insight into optimizing the electrochemical performance of Li-S batteries.