Anion Design-Enabled High-Performance Cobalt-Based 3D Conductive Interlayers to Suppress the Shuttle Effect for Lithium–Sulfur Batteries

Recently, transition-metal compounds (TMCs) with unique adsorptive and catalytic properties have shown great promise in lithium–sulfur (Li–S) batteries to inhibit the shuttle effect. However, current studies mostly focus on the morphology control of one specific TMC, while the relationship between the composition and performance is insufficiently revealed. Nevertheless, the polarity and catalytic activity are largely dependent on the components of TMCs, especially the anion species. Herein, we take Co–X (X = O, P, and S) compounds as example compounds and systematically investigate the compositional effects of Co–X compounds on their inhibition abilities for the shuttle effect. To conduct the investigation, CoS2, CoP, and Co3O4 flowers with identical morphologies and nanostructures were successfully grown on 3D conductive self-supporting carbon nanofibers (CNFs) via a facile electrospun method combined with post-heat treatment. When tested in Li–S batteries, the CoS2/CNF interlayer outperforms its phosphide and oxide counterparts, displaying the strongest adsorption ability and the highest catalytic activity toward polysulfides. Impressively, Li–S batteries coupled with CoS2/CNF interlayers exhibit outstanding electrochemical performance with a high specific capacity of 1115.2 mA h g–1 and enhanced cycling stability of 884.4 mA h g–1 after 200 cycles. We believe such an anion design strategy could open a new avenue for constructing high-performance Li–S batteries.