ZnFe2O4 hollow rods enabling accelerated polysulfide conversion for advanced lithium-sulfur batteries. (10th May 2022)

• Record Type: Journal Article
• Authors: Zhou, Lei; Danilov, Dmitri L.; Qiao, Fen; Eichel, Rüdiger-A.; Notten, Peter H.L.
• Is Part Of: Electrochimica acta. Volume 414(2022)
• Publication Date: 2022-05-10
• Subjects: Lithium-sulfur batteries -- Metal oxides -- Polysulfide conversion -- Accelerated kinetics -- Reaction activation energies; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140231
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: A novel hollow ZnFe2 O4 rod is developed to enhance sulfur cathode utilization. ZnFe2 O4 rods significantly enhance the liquid-solid conversion of sulfur. The reaction overpotential and activation energy of sulfur cathodes are reduced. Effective anchoring of sulfur is a prerequisite for accelerated redox conversion. Abstract: The high energy density and favorable cost-effectiveness make lithium-sulfur (Li-S) batteries one of the most attractive energy storage systems. However, the low sulfur utilization and poor cycle life, resulting from the losses of soluble polysulfide intermediates, and their sluggish redox conversion process, severely impede practical applications of reliable Li-S batteries. Effectively inhibiting the polysulfide diffusion and accelerating their conversion is beneficial to enhance the performance of sulfur cathodes. Herein, a novel carbon-free ZnFe2 O4 hollow rod has been developed as an advanced host material to confine polysulfides within the cathode and accelerate the redox conversion during cycling. The soluble polysulfides anchored by the ZnFe2 O4 hollow rod structure are shown to be rapidly converted to sulfur and lithium sulfides. Detrimental polysulfide diffusion is therefore effectively inhibited. The redox kinetics of sulfur cathodes has been systematically investigated, revealing that the ZnFe2 O4 host can improve the activity for Li2 S deposition, facilitate lithium-ion diffusion, and lower the reaction energy barriers for the multistep phase transition of sulfur. As a result, the developed S@ZnFe2 O4 composite cathodes exhibit an improved cycling capacity of 1158 mAh g −1 . These results demonstrate that the accelerated redox conversion of anchored polysulfides is essential for enhancing the electrochemical performance of Li-S batteries. Graphical abstract: A novel carbon-free ZnFe2 O4 hollow rod material has been developed to inhibit the losses of sulfur and enhance the electrode kinetics for lithium-sulfur batteries. The ZnFe2 O4 rods effectively anchor sulfur species and significantly reduce the activation energies of sulfur redox reactions, enabling accelerated electrochemical conversion of sulfur cathodes. Image, graphical abstract