Cobalt-iron oxide nanoparticles anchored on carbon nanotube paper to accelerate polysulfide conversion for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li2S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe2O4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe2O4 nano particles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/ CoFe2O4/CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g(-1) and remaining a high reversible capacity of 642.6 mAh g(-1) after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

Lithium-sulfur (Li-S) batteries have great potential as energy storage devices due to their high theoretical specific energy, low cost, and abundant resources. However, there are still many challenges in the practical performance of the sulfur cathode. This study proposes the use of CoFe2O4 nanoparticles anchored on carbon nanotube (CNT) paper as a free-standing sulfur host to address these challenges. The resulting S/CoFe2O4/CNT paper cathodes show impressive electrochemical performance with high discharge capacity and long cycling stability.