Nitrogen‐Deficient Graphitic Carbon Nitride/Carbon Nanotube as Polysulfide Barrier of High‐Performance Lithium‐Sulfur Batteries

Abstract

AbstractLithium‐sulfur (Li−S) batteries have been attracting growing interest in the past few years due to their outstanding theoretical energy density, but the lower cycle performance and especially the migration of polysulfides significantly inhibited its applicability. Herein, we propose a novel strategy for trapping lithium polysulfides (LiPSs) by combining nitrogen‐deficient graphitic carbon nitride (g‐C3N4–x) and carbon nanotubes (CNTs) to form a functional interlayer between the separator and sulfur cathode in Li−S batteries. The defect chemistry present in g‐C3N4–x not only improves the chemical affinity toward polysulfides but also catalyzes the polysulfide reactions. Besides, the interwoven scaffold‐like CNT network in the g‐C3N4–x/CNT composite accelerates the process of electron transfer. Based on this synergistic effect, the cells with g‐C3N4–x/CNT‐modified separators showed a remarkable discharge capacity of 1128 mAh g−1 at 0.2 C, and a reversible capacity of 774 mAh g−1 after 100 cycles, indicating an efficient strategy toward high‐performance modified separators.