MXene-Based Co, N-Codoped Porous Carbon Nanosheets Regulating Polysulfides for High-Performance Lithium–Sulfur Batteries

Abstract

In virtue of their distinctive superiorities, lithium-sulfur (Li-S) batteries were deemed as novel and potential energy storage equipment. However, the low actual energy density and rapid capacity fading are still hindering their practical applications. Herein, MXene-based Co, N-codoped porous carbon nanosheets (MCoNPCNSs) are first developed as sulfur hosts by in situ self-assembly of the bimetallic zeolite imidazole framework on Ti₃C₂T_<i>x</i> MXene nanosheets followed by calcining and etching treatments. Co, N codoping on the one hand highly enhances the adsorptivity to polysulfides and on the other hand significantly promotes the kinetics of sulfur cathodes. Therefore, the MCoNPCNSs/S-M-PP electrode achieves a high capacity of 1340.2 mA h g^-1 in the first-cycle discharge process at 0.2 C and an exceptional capacity retention of 914.7 mA h g^-1 after 1000 cycles at 1 C. Moreover, the integrated structure of the cathode and separator imparts the MCoNPCNSs/S-M-PP electrode a significantly elevated gravimetric energy density of 1211.8 W h kg^-1. Therefore, the integrated MCoNPCNSs/S-M-PP electrode provides a delighted direction for constructing the potentially practical Li-S batteries.