Lithiumesulfur (LieS) batteries have a high theoretical specific
energy, which is 5 times greater than that of lithium-ion batteries
[1e3]. On the other hand, the advantages such as natural abundance,
low cost, and environmental friendliness of sulfur also bring
additional benefits for large-scale commercialization of LieS batteries.
Therefore LieS batteries have been considered to be one of
the most promising choices for next generation high energy
rechargeable batteries.
However, there are still some key challenges hindering the
practical application of LieS batteries. First, low active materials
utilization in the cathode as both sulfur and its final discharge
product Li2S is electronically and ionically insulating [4]. Second,
low coulombic efficiency and poor cycle life due to the soluble intermediate
products during the charge/discharge process (Li2SX,
3 X 8), which can cause irreversible capacity loss and wellknown
“shuttling effect” [5]. In order to enhance the conductivity
of sulfur, accommodate the volume changes during lithiation/
delithiation and suppress diffusion of dissolved polysulfides out of
the cathode, a variety of carbon materials and conductive polymers
have been employed to fabricate sulfur/carbon composites [6e12],
sulfur/conductive polymer composites and polymer coated sulfur/
carbon composites [13e18]. With these cathode composites, the
electrochemical performance of LieS batteries has been improved
greatly. However, the enhanced electrochemical performance of
sulfur composite cathode is usually compromised by the lower
sulfur content and sulfur loading mass, which greatly reduce the
practical energy density of LieS batteries