Few-Layer MoS2-Decorated MoO2 for High-Density Exposed Catalytic Heterointerfaces in Lithium-Sulfur Batteries.

Lithium-sulfur batteries are severely limited by polysulfide shuttling and sluggish sulfur redox kinetics. Efficient catalysis in lithium-sulfur (Li-S) batteries requires not only intrinsically active catalyst materials but also catalytic interfaces with high structural exposure and electrochemical accessibility. Here, a few-layer MoS2-decorated MoO2 composite integrated with carbon nanotubes is developed as a functional separator coating with a high density of exposed catalytic heterointerfaces. In this composite, polar MoO2 strongly anchors lithium polysulfides, while highly dispersed few-layer MoS2 nanoflakes provide abundant MoO2-MoS2 heterointerfaces, accelerating polysulfide conversion. Meanwhile, the MoO2-MoS2 junction provides balanced polysulfide adsorption and pronounced charge redistribution, thereby promoting the activation and subsequent conversion of reaction intermediates. Li2S nucleation tests and in situ x-ray diffraction further verify the accelerated kinetics of polysulfide conversion and the improved reversibility of Li2S formation. As a result, Li-S cells deliver a high specific capacity of 1236 mAh g-1 at 0.2 C and retain 475 mAh g-1 after 1000 cycles at 1 C, highlighting the promise of constructing high-density exposed catalytic heterointerfaces for high-performance Li-S batteries.