Nanoparticle Assembled Mesoporous MoO2 Microrods Derived from Metal Organic Framework and Wrapped with Graphene as the Sulfur Host for Long-Life Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are highly potential for next-generation electrochemical energy storage due to their high energy density. However, low conductivity of the sulfur cathode, dissolution, and poor conversion kinetics of lithium polysulfides (LiPSs) are the key challenges. Herein crispy rice-like nanoparticle assembled mesoporous MoO2 microrods derived from metal organic frameworks and wrapped with graphene (MoO2/rGO) are fabricated, exhibiting high electron and lithium ion conductivity from the inherent metallic conductivity for MoO2 and mesoporous-structural microrod morphology, physical confinement for LiPSs through mesopores, chemical adsorption, and catalytic conversion of LiPSs by formation of thiosulfates (polythionates) due to moderate redox potential for MoO2. The S-MoO2/rGO cathode shows a discharge capacity of 1145 mAh g(-1) at 0.5C and keeps at 1027 mAh g(-1) after 500 cycles, corresponding to an average capacity decay rate of 0.02% per cycle. Specifically, an ultralong cycling life with a low capacity decay of 0.016% only over 3200 cycles at 3.0C is the best performance in long-life Li-S batteries among reported sulfur hosts.