A three-dimensional conductive cross-linked all-carbon network hybrid as a sulfur host for high performance lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries, as one of the most promising energy storage devices, have attracted widespread attentions due to their high theoretical energy density and environmental friendliness. However, the commercialized application of Li-S batteries is still restricted by several problems, including the dissolution of polysulfides in electrolyte and low conductivity of sulfur. Herein, a three-dimensional conductive cross-linked all-carbon network as a host matrix of sulfur is rationally designed and constructed using biomass silkworm faeces derived porous carbon (SFPC), reduction graphene oxide (rGO) and carbon nanotubes (CNTs) via a one-pot heat treatment approach. Meanwhile, it is found that the amounts of rGO and CNTs added have a great influence on the electrochemical properties of electrode. The optimum contents of CNTs and GO were explored, which are both 5% (the as-prepared material denoted as 55-PGC@SFPC). The obtained 55-PGC@SFPC/S with high content sulfur of 70% as a cathode of Li-S batteries exhibits the initial discharge capacity of 1354 mAh g-1 at 0.1 C, excellent rate capacity of 478 mAh g-1 at 3 C, admirable long-term cycling stability with a high reversible capacity of 414 mAh g-1 after 1000 cycles and low capacity decay rate of 0.035% per cycle. The designed three-dimensional network structure could lead to a quick diffusion of Li+/e- and a good impeding effect for polysulfides dissolution, which is beneficial for developing the advanced energy storage device of Li-S batteries.