Establishing highly efficient absorptive and catalytic network for depolarized high-stability lithium-sulfur batteries

Practical operation of lithium-sulfur (Li-S) batteries with high sulfur loading and efficient/stable sulfur conversion requires the suppression of the lithium polysulfides (LiPSs) shuttling and the facilitation of ion and electron transfer on the electrode material surface. Herein, a multifunctional current collector, composed of Ag@polypyrrole (PPy) coated electrospun carbon nanofibers (CNF) framework, was rationally designed to construct a highly efficient catalytic/absorptive/conductive network to improve the performance of Li-S batteries under practical operation condition. At the molecular scale, the Ag@PPy molecular not only effectively inhibits LiPSs shuttle effect, but also achieves the fast sulfur catalysis and depolarization during charge transfer due to the high conductivity of Ag nanoparticles. At the electrode scale, the three-dimensional (3D) robust fibrous nanostructure provides abundant physical space to realize high sulfur loading, maintains electrode integrity during large volume change of active sulfur and under mechanical abuse condition, as well as enables the high-flux Li⁺ diffusion and electrolyte flow. Consequently, Li-S batteries with the CNF/Ag@PPy current collector delivered excellent cycling stability (capacity fading of 0.048% per cycle over 500cycles at 1.0C) and high energy density (234.2 Wh kg_cell^-1 under high sulfur loading of 9.77 mg cm⁻²). Flexible Li-S batteries are also fabricated indicating the feasibility of the CNF/Ag@PPy current collector in flexible devices.