Sulfur encapsulated in porous hollow CNTs@CNFs for high-performance lithium–sulfur batteries

Abstract

Significant challenges for the commercialization of a lithium–sulfur battery include its rapid capacity fading and low power capability. Encapsulating the sulfur in pores of small volume of a porous carbon material alleviates this problem. We report a carbon–sulfur nanoarchitecture that encapsulates sulfur in porous hollow carbon-nanotubes@carbon-nanofibers (CNTs@CNFs) with a high Brunauer–Emmett–Teller (BET) specific surface area of 1400 m² g⁻¹ and a total pore volume of 1.12 cm³ g⁻¹. As a cathode, this material with 55 wt.% sulfur shows a high capacity of ∼1313 mA h g⁻¹ at 0.2 C, 1078 mA h g⁻¹ at 0.5 C, 878 mA h g⁻¹ at 1 C, 803 mA h g⁻¹ at 1.5 C, 739 mA h g⁻¹ at 2 C, and 572 mA h g⁻¹ at 5 C, and maintains ∼700 mA h g⁻¹ at 1 C after 100 cycles and 430 mA h g⁻¹ at 5 C after 200 cycles, which makes it a superior cathode material for a rechargeable Li–S battery.