• Qiao, Fen
• Notten, Peter H. L.
• Eichel, Rüdiger A.
• Zhou, Lei
• Danilov, Dmitry

Abstract

<p>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 ZnFe₂O₄ 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 ZnFe₂O₄ 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 ZnFe₂O₄ host can improve the activity for Li₂S deposition, facilitate lithium-ion diffusion, and lower the reaction energy barriers for the multistep phase transition of sulfur. As a result, the developed S@ZnFe₂O₄ 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.</p>

Topics

• Deposition
• density
• impedance spectroscopy
• Carbon
• energy density
• phase
• composite
• phase transition
• Lithium