Boosting\nLithium–Sulfur Battery Performance\nby Integrating a Redox-Active Covalent Organic Framework in the Separator

Abstract

Lithium–sulfur\nbatteries are getting more attention in energy\nstorage and conversion fields due to their high theoretical capacity\nand specific energy density. Nevertheless, the dissolution of polysulfides\nresults in their poor cycle stability, which is the major issue in\npractical use. To overcome the challenge, we report a new strategy\nby employing a redox-active covalent organic framework as the separator\nin lithium–sulfur batteries. The one-dimensional pore channels\nof the covalent organic framework provide a fast transport pathway\nfor the lithium ion. And the pyridine units of the framework not only\nenhance the chemical adsorption of sulfur but also catalyze the charge\nand discharge processes. By virtue of these features, the specific\ncapacity at 0.2 C is 977 mAh g^–1 after 100 cycles,\nwhich is 5.2 times higher than that of the pristine separator-based\nbattery. Additionally, the specific capacity achieves 826 mAh g^–1 at 1 C after 250 cycles.