Constructing Wide-Temperature Lithium-Sulfur Batteries by Using a Covalent Organic Nanosheet Wrapped Carbon Nanotube

Lithium-sulfur (Li-S) batteries hold the superiority of eminent theoretical energy density (2600 Wh kg-1). However, the ponderous sulfur reduction reaction and the issue of polysulfide shuttling pose significant obstacles to achieving the practical wide-temperature operation of Li-S batteries. Herein, a covalent organic nanosheet-wrapped carbon nanotubes (denoted CON/CNT) composite is synthesized as an electrocatalyst for wide-temperature Li-S batteries. The design incorporates the CON skeleton, which contains imide and triazine functional units capable of chemically adsorbing polysulfides, and the underlaid CNTs facilitate the conversion of captured polysulfides enabled by enhanced conductivity. The electrocatalytic behavior and chemical interplay between polysulfides and the CON/CNT interlayer are elucidated by in situ X-ray diffraction detections and theoretical calculations. Resultantly, the CON/CNT-modified cells demonstrate upgraded performances, including wide-temperature operation ranging from 0 to 65 degrees C, high-rate performance (625 mAh g-1 at 5.0 C), exceptional high-rate cyclability (1000 cycles at 5.0 C), and stable operation under high sulfur loading (4.0 mg cm-2) and limited electrolyte (5 mu L mgs-1). These findings might guide the development of advanced Li-S batteries. A composite of covalent organic nanosheet-wrapped carbon nanotubes (CON/CNT) is synthesized as an electrocatalyst for Li-S batteries. The CON/CNT interlayer possesses duplex chemical sites, including imide and triazine units, enabling effective adsorption of polysulfides. Meanwhile, the underlying CNTs facilitate the conversion of adsorbed polysulfides, leading to stable battery performance across a wide temperature range from 0 to 65 degrees C.image