Flexible and free-standing carbon nanofiber matt derived from electrospun polyimide as an effective interlayer for high-performance lithium–sulfur batteries

For advanced energy storage devices, high-performing and stable lithium–sulfur (Li–S) battery is one of the most prominent alternatives. However, one of the major challenges for Li–S battery development is to overcome the rapid capacity decay arising from polysulfide dissolution. Herein, a self-standing carbon nanofiber (CNF) matt derived from polyimide is fabricated by a simple, yet versatile electrospinning technique. An optimized CNF matt is introduced between sulfur cathode and separator that act as an interlayer, providing continuous pathway for electronic and ionic interactions, which accommodates volume expansion and impedes dissolution of the polysulfide intermediate species. The resulting sulfur-based Li–S cell delivers high specific initial discharge capacity of 1474 mAh g−1 and retains capacity of 1014 mAh g−1 even after 100 cycles at 1 A g−1 current density. Further, the cell demonstrated good reversible capacity for 500 cycles as well as excellent rate capability. This study demonstrates that CNF matt provides significant improvement in capturing polysulfides intermediate species from electrolyte that can extend the life span of sulfur cathode for long-standing applications.