In situ synthesis of 3D sulfur-doped graphene/sulfur as a cathode material for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are attractive due to the overwhelming advantage of theoretical energy density and low sulfur cost. Preventing the shuttle of polysulfides and maintaining the high sulfur content are two of the primary challenges. 3D sulfur doped graphene (S-3DG) not only promises enough space to accommodate sulfur, but also increases the binding of polysulfides intermediates through chemical bonding. However, strategies for constructing sulfur doped 3D sulfur/graphene (S-3DG/S) are either complex or involve toxic reagents. The sulfur-containing decolorizer (NaHSO3) as heteroatom doping source as well as reducer is utilized in synthesis S-3DG/S for lithium sulfur batteries via one-pot method. The results show that sulfur is successfully introduced into the 3DG/S framework with S-doped content of 1.8 wt%. The S-3DG/S composites with high loading (80 wt%) of sulfur deliver a high capacity retention of 93.9% after 100 cycles and demonstrate a low capacity-decay rate of 0.085% per cycle after 350 cycles at 0.5 C rate. This low-cost and scalable method paves a novel way to the practical application of Li-S batteries.