Nanopolyhedron Co–C/Cores triggered carbon nanotube in-situ growth inside carbon aerogel shells for fast and long-lasting lithium–sulfur batteries

Abstract

The improved physicochemical immobilization and catalytic redox conversion of lithium polysulfides (LiPSs) intermediates are considered to be a desirable solution to enhance the sulfur electrochemistry in lithium-sulfur (Li–S) batteries. Herein, we for the first time, reported the fabrication of the core-shell structure composed of cobalt-doped carbon nano-tube (CNT) assembled polyhedron core derived from the cobalt metal-organic frameworks (Co-MOFs)@graphitized porous carbon aerogel shell as the sulfur reservoir material for Li–S batteries. The obtained sulfur cathodes exhibited excellent electrochemical performance, including a high reversible capacity (939.9 mAh g−1 at 0.1C), outstanding areal capacity (3.35 mAh cm−2 after 50 cycles, under a low electrolyte/8.3 μL mgs−1), and superior cycling stability (the capacity decay rate of 0.087% per cycle after 500 cycles at 1C). The improvement in electrochemical performance could be attributed to the unique core-shell architecture: the multiple polyhedron Co–C cores not only provide a multiple-point catalytic center for LiPS conversion, but also serves as the polar material to inhibit the migrating of polysulfides by chemical interaction; More importantly, the graphitized porous carbon aerogel shell provides a fast transport channel for Li+/e− diffusion, and also sufficient free space for the sulfur reservoir and Li2S2/Li2S deposition.