Bifunctional N,S Dual-Doped Hollow Carbon Cloth as a Sulfur Host and Interlayer for Mitigating the Polysulfide Shuttle of Li–S Batteries

Abstract

Lithium–sulfur batteries with a high theoretical capacity and low cost have become one of the hot candidates for next-generation high-energy storage systems. However, the practical energy density and cycle stability are still limited by the insulating properties of sulfur and polysulfide shuttle effect. Herein, an N,S dual-doped hollow carbon cloth with robust flexibility is constructed by the impregnation and pyrolysis method using thiourea inducement while exhibiting the bifunctional applications of self-supporting sulfur hosts and interlayers. The introduction of N,S heteroatoms appropriately modulates the electron cloud density and causes defects in carbon cloth, thereby increasing the number of active sites for synergistically trapping polysulfides. Besides, the interwoven carbon skeletons form a conductive network to further accelerate the electronic transmission and electrochemical conversion of polysulfides. Consequently, the self-supporting sulfur cathode achieves a long life of 1000 cycles. Especially as a functional interlayer, the high initial discharge capacity of 1028.7 mAh·g^–1 and reversible capacity of 794.5 mAh·g^–1 are obtained at 0.2 C after 200 cycles. After 1000 cycles at 2.0 C, the capacity decay per cycle is only 0.02%. Even with 5.7 mg·cm^–2 sulfur loading, the areal capacity of 4.3 mAh·cm^–2 is also obtained.