Multiple-Active-Site Catalysis in a Polyoxovanadate-Embedded Cobalt-Triazole Framework for Accelerated Sulfur Redox Kinetics in Lithium–Sulfur Batteries

Sluggish redox reaction kinetics of sulfur species, especially rate-determining steps of the deposition and decomposition of Li2S, severely hinder the application of lithium-sulfur batteries. Herein, we synthesized a composite, namely a polyoxovanadate-embedded cobalt-triazole framework ([Co3(4-NH2-trz)6][V6O18]·3H2O) mixed with reduced graphene oxide (Co,V-POMOFs@rGO), which displays effective immobilization and catalytic conversion of polysulfides, especially the formation and oxidation of Li2S, originating from numerous active sites and high atomic utilization. Accordingly, the Li-S coin cell assembled by the Co,V-POMOFs@rGO composite modified separator delivers a high initial specific capacity of approximately 1500 mAh g-1 at 0.2 C and good cycle stability with a specific capacity of 568 mAh g-1 after 500 cycles and a low-capacity decay rate of 0.08% per cycle at 1 C. This study offers a perspective for designing high performance POMs-based catalysts for Li-S batteries.