Accelerating sulfur reduction kinetics through establishing a balancing network in adsorption-catalysis-conversion of polysulfide by sulfur-affinity metal iron

Adsorption and catalytic conversion of polysulfides plays a pivotal role in improving the reaction dynamics and mitigating the shuttle effect within lithium-sulfur (Li-S) batteries. Nevertheless, overly strong adsorption will commonly hinder the conversion of polysulfides leading to low cycling stability. Herein, x Fe-CoP catalysts were designed and synthesized by introducing the sulfur-affinity metal Fe to establish a synergistic balancing network of “moderate capturing” “accelerated catalysis” and “rapid conversion” of polysulfide to improve the Li-S reaction kinetics. In combination with theoretical analysis, we evaluate the affinity effect between catalysts with different Fe content and polysulfide, and emphasize the role of moderate adsorption. Consequently, the sulfur-loaded x Fe-CoP ( 0.33 Fe-CoP/S) delivered a high initial discharge capacity of 1441 mAh g −1 at 0.1C and manifested impressive cyclic performances with 84.2 % capacity retention over 500 cycles at 1.0C. Even with a sulfur loading of 6.5 mg cm −2 and low electrolyte/sulfur ratio (E/S) of 3.7 µL mg −1 , the cell demonstrates an attainable areal capacity of 7.0 mAh cm −2 . This research is poised to establish a theoretical framework for developing high-capacity, long-life Li-S batteries with high sulfur load and lean electrolyte requirements.