Flexible carbon@graphene composite cloth for advanced lithium–sulfur batteries and supercapacitors with enhanced energy storage capability

Abstract

Flexible carbon@graphene composite cloth was fabricated, and the resultant composite cloth consists of core–shell hollow structured carbon/graphene hybrid fibers with abundant micro- and mesoporosity and hydrophilic functionality. These unique features enable the composite cloth to be a promising material for energy storage application. As an efficient polysulfide adsorbent, the composite can be applied in lithium–sulfur batteries by being sandwiched between the sulfur cathode and polymeric separator. With this novel configuration, a high reversible capacity of ca. 900 mAh g−1 and excellent cycle-life has been achieved, which is ascribed to the excellent polysulfides adsorption and confinement capability of the special core–shell and hollow structured porous hybrid fibers. Additionally, the composite cloth can be applied in supercapacitors as a flexible binder-free electrode, exhibiting a high specific capacitance of 271 F g−1 (360 F cm−3) at 0.1 A g−1 in 6 M KOH, as well as excellent rate capability and cycling stability. The assembled symmetric supercapacitor supplies a high energy density of up to 9.4 Wh kg−1 (12.5 Wh L−1) with a power density of 25.0 W kg−1 (33.3 W L−1) and remains 5.7 Wh kg−1 (7.6 Wh L−1) with 4.5 kW kg−1 (6.0 kW L−1).