Imparting selective polysulfide conversion via geminal-atom moieties in lithium-sulfur batteries

Electrocatalysis in lithium-sulfur (Li-S) chemistry has readily stimulated extensive interests because of its irreplaceable role in realizing high-performance batteries. In this sense, achieving accelerated catalytic conversion of polysulfides is essential for the shuttle inhibition and kinetics promotion. Nonetheless, selective catalysis of sulfur reduction/evolution reaction via precise control over electrocatalytic mediators is still in its infancy. Moreover, specific catalytic role of the active metal center in dual-atom catalyst sites remains relatively unexplored. Herein, we utilize a salt-confined strategy to fabricate FeCo geminal-atom moieties dispersed on N-doped carbon support (FeCo-NC) for Li-S batteries throughout leveraging Fe and Co single-atom species with selective catalysis. The enhanced bidirectional conversion kinetics of polysulfide with the incorporation of Fe and Co atoms are uncovered throughout theoretical simulation and electrokinetic analysis. As a result, the FeCo-NC endows a rechargeable Li-S battery with excellent capacity retention rate of 98.6% after 100 cycles at 0.2 C and cycling stability with a decay rate of 0.033% per cycle over 2000 cycles at 3.0 C. More encouragingly, the assembled Li-S cell at a sulfur loading of 6.7 mg cm-2 can harvest an areal capacity of 7.13 mAh cm-2, signifying the rational design of geminal-atom mediators to dictate selective catalysis behaviors toward practical Li-S batteries.