Boosting sulfur-based cathode performance via confined reactions in covalent organic frameworks with polarized sites

Abstract

The widespread promotion of the sulfur-based cathode is continuously threatened by the dissolution or slow kinetic reactions of polysulfides, resulting in a deterioration of capacity and volume expansion. Herein, a hierarchical imine-based covalent organic framework (COFs) with AA stacking structure is constructed as a sulfur host matrix. The one-dimensional channels in COF are decorated with polarized methoxy groups which can confine and immobilize sulfur species through weak interactions, alleviating the shuttle effect during the battery tests. The composite electrode (COF@S) is fabricated through the melt-diffusion method in one-pot synthesis and exhibits a slow fading rate (0.20% each cycle) in a 0.5 C stability test. A promising mechanism for constructing the cathode composite is demonstrated in lithium-sulfur chemistry in this work.