A Novel Mesoporous Carbon Pocket with Single Atom Cr Sites for High Performance Lithium-Sulfur Battery

Abstract

Lithium-sulfur batteries (LSBs) are considered one of the most promising next-generation energy storage devices. However, their practical application is limited by the sluggish conversion kinetics and shuttle behavior of lithium polysulfides (LiPSs). In this work, we employ a facile salt template and micelle-mediated co-assembly strategy to synthesize atomic Cr dispersed mesoporous N-doped carbon pocket (denoted as Cr-mNC pocket). The designed Cr-mNC pocket exhibits uniform and ordered mesoporous caged morphology with a high surface area (843.5 m2 g-1), large pore volume (0.184 cm3 g-1), and uniform mesopore size (3.7 nm). The mesoporous structure offers a facilitated pump to promote electron/ion transportation while exposing more catalytic sites. These advantages enable the Cr-mNC pocket modified membrane to facilitate Li+ diffusion, enhance LiPSs adsorption, and accelerate electrochemical reaction kinetics for polysulfide conversion. Consequently, LSBs with Cr-mNC modified separator show a high sulfur utilization (1405 mAh g-1 at 0.2 C), a remarkable rate performance (776 mAh g-1 at 5 C), a low capacity decay rate of 0.047% per cycle at 2 C over 1000 cycles, and even remain at 4.47 mAh cm-2 after 100 cycles with a high sulfur load of 5.0 mg cm-2.

Keywords: Mesoporous materials, Lithium-sulfur battery, hollow structures, Soft Template Assembly