Manganese Oxide Nanosheets with Mixed Valence States as a Separator Coating for Lithium-Sulfur Batteries

The shuttling effect of soluble polysulfides and theinadequateconductivity of sulfur and lithium sulfide impede the practical utilizationof lithium-sulfur batteries. To address this issue, the polar & delta;-MnO2 nanosheets with a 2D morphology can provideabundant anchor and catalytic sites for polysulfides. However, thepoor intrinsic conductivity restricts the transformation ability.Herein, we introduce mixed Mn4+/Mn3+ valencestates in & delta;-MnO2 nanosheets by a facile annealingmethod to promote the redox kinetics of polysulfides. This treatedMnO(2) maintains its 2D morphology, providing abundant absorptionsites for polysulfides, while the introduction of mixed valence statesenhances charge transfer and facilitates reaction kinetics. As a result,the lithium-sulfur battery achieves high areal capacities of7.0 mAh cm(-2) at 0.56 mA cm(-2) and4.0 mAh cm(-2) at 1 mA cm(-2) after100 cycles with a sulfur loading of 10.91 mg cm(-2) and an E/S ratio of 6.46 & mu;L mg(-1).

Automated summary

To address the issues of shuttle effect and inadequate conductivity in lithium-sulfur batteries, researchers introduced mixed Mn4+/Mn3+ valence states in polar δ-MnO2 nanosheets through a facile annealing method. This led to enhanced redox kinetics of polysulfides. The treated MnO2 maintained its 2D morphology, providing abundant absorption sites, while the introduction of mixed valence states improved charge transfer and reaction kinetics. As a result, the lithium-sulfur battery achieved high areal capacities of 7.0 mAh cm(-2) at 0.56 mA cm(-2) and 4.0 mAh cm(-2) at 1 mA cm(-2) after 100 cycles with a sulfur loading of 10.91 mg cm(-2) and an E/S ratio of 6.46 μL mg(-1).