Micro-/mesoporous Co-NC embedded three-dimensional ordered macroporous metal framework as Li-S battery cathode towards effective polysulfide catalysis and retention

The practical utilization of lithium-sulfur (Li-S) batteries is obstructed by the shuttle effect and sluggish conversion kinetics of the lithium polysulfides (LiPS). Herein, cobalt nanoparticles embedded N-doped carbon composite (Co-NC) decorated metallic tin with three-dimensionally ordered macroporous (3DOM) structure is designed to deal with these issues. The ordered interconnected macropores of the unique hierarchical structure can provide smooth Li ion transport, and the micro-/mesopores of Co-NC derived from ZIF-67 can trap polysulfides. Additionally, the highly conductive metal Sn as 3DOM skeleton accel-erates charge transfer and strengthens the LiPS adsorption. Meanwhile, the embedded Co-NC further facilitates the polar adsorption of LiPS as well as its conversion kinetics. Benefiting from these features, the Co-NC@Sn (NH3) composite shows a relatively low capacity fading rate of 0.045 % per cycle over 500 cycles at 1 C. Even with raised sulfur loading of 5.2 mg cm(-2), a high areal capacity of 4.65 mAh cm(-2) can be obtained. Pouch cell fabricated with Co-NC@Sn (NH3) delivers a high discharge capacity of 701 mAh g(-1) under high sulfur loading of 4.50 mg cm(-2), implying the superiority of the S/Co-NC@Sn (NH3) cathode. This work provides a new strategy in efficient sulfur immobilizer design for advanced Li-S batteries development. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A three-dimensionally ordered macroporous carbon composite was designed to enhance the performance of lithium-sulfur batteries, resulting in low capacity fading rate and high discharge capacity. This new structure provides smooth Li ion transport, traps polysulfides, accelerates charge transfer, and facilitates the adsorption and conversion kinetics of lithium polysulfides.