Integrated host configuration of flexibly fibrous skeleton towards efficient polysulfide conversion and dendrite-free behavior in stable lithium-sulfur pouch cells

The commercialization of lithium-sulfur (Li-S) batteries is obstructed by the sluggish sulfur electrochemical reaction, severe polysulfide shuttling effect, and damaging dendritic lithium growth. Herein, a three-dimensional (3D) conductive carbon nanofibers skeleton-based bifunctional electrode host material is fabricated, which consists of a two-dimensional (2D) ultra-thin NiSe2-CoSe2 heterostructured nanosheet built on one-dimensional (1D) carbon nanofibers (NiSe2-CoSe2@CNF). When serving as cathodic host, the heterostructured NiSe2-CoSe2@CNF offers a synergistic function of polysulfide confinement and catalysis conversion. The S/NiSe2-CoSe2@CNF cathode shows outstanding cycling stability of 0.03% capacity decay rate per cycle over 500 cycles at 1 C. As anodic host, the NiSe2-CoSe2@CNF with high-flux Li+ diffusion property and good lithiophilic capability realizes dendrite-free Li plating/stripping behavior. Benefiting from these synergistically merits, the Li-S full cell with S/NiSe2-CoSe2@CNF|Li/NiSe2-CoSe2@CNF electrodes exhibits excellent electrochemical performance including a high specific capacity of 1021 mA h g−1 over 100 cycles at 0.2 C and reversible areal capacity of 3.05 mA h cm−2 under a high sulfur loading of 4.33 mg cm−2 at 0.1 C. The pouch cell also delivers ultra-stable Li/S electrochemistry. This study demonstrates a rational and universal electrode construction strategy for developing practical and high-energy Li-S batteries.